The BMS/Charger thing has actually got me in a rage these days. The stupidity and greed are palpable in the air. But it is not innocent stupidity and greed. It is probably the most damaging thing being done today in EV land.
The U.S. Congress and Senate, two of the exemplar houses of stupidity and greed, have enthusiastically passed the most idiotic thing to come out of our legislative body in – well, DAYS. In an absolutely mindless pander to the BLIND if you can imagine, they have legislated that all electric vehicles have to have a NOISE maker so they are as loud and annoying as the other cars on the road. This, so blind pedestrians don’t get clobbered by an EV.
How many incidents of this have occurred? Of what magnitude is this growing threat to life and limb. NONE CITED. But if only ONE blind child is saved…. you know the story.
Meanwhile, David Andreas, Dmitri, Rich Rudmann, and the entire BMS crowd continue to burn cars to the ground with reckless and mindless abandon – all for such a pathetic little bit of profit I can’t imagine any of them being able to buy pizza with it. It is madness.
The latest from Norway, a converted Nissan burnt up while charging on a large ferry, severely damaging the ship. Apparently a SECOND one burned in a parking lot. Video here:
http://ekstrabladet.dk/112/article1453404.ece
In both cases, the cars burned while charging. Again, on the ship, it was in the wee hours of the morning (end of charge) while everyone was asleep.
Here’s a link to a very nice brochure from the company that made the car. http://media2.ev-tv.me/Qashqai_Electric.pdf
It looks like a very nice and very professional conversion and they tout safety as their very highest priority. Of course they use a BMS – for safety.
The article vaguely alludes to a “short” and an “unauthorized plug”. Of course. Since 3/4 of our knowledgeable community can’t get this right, what do you expect the media reaction to be.
I’ll tell you what it is to be. As more electric cars get on the road, and as more of these needless fires get to star in thir own news video, if they’ll pass legislation to require noise on electric cars to save nobody who’s ever been injured or threatened with one, imagine the field day they’ll have making electric car conversions ILLEGAL. Only professionals should be playing with these incendiary devices and high voltages. It’s in the interest of public safety.
It is absolutely inevitable. The honeymoon occurred in obscurity. And of course, as Pogo noted 3/4 of a century ago, “We have met the enemy…. and he is US. ”
We should call it the BMS conspiracy. And it seems that we are all going to Hell in a hand basket. All I can say is that we have to stay the course and keep spreading the word.
Yes I agree , BMS are dangerous , because people that buy them trust them to disconnect the usually cheap chargers, It´s easy to put a relay and a thermostat to disconnect the charger if the temperature gets to high.
Also there is news from ThunderySky… sorry now is Winston Battery , finally the LiS batteries are listed on the products now it´s a mater of time util they are available , this could mean great leap foward
Personally, I cannot hear most of the late model ICE cars when they are travelling slow or idling at a stop light, they are very quiet now, just as quiet as an EV is to the average human ear in many cases. If they insist on implementing such an insane law like this, then I propose all cars should be required to meet a certain decibel level, fair is fair or ridiculous is ridiculous.
Next they will insist that an EV car should exhale some sort of poisonous gas smell so that the hearing impaired folks can tell the car is running.
If Canada adopts the same attitude, then I will be forced to install a subwoofer that is playing a nitro burning funny car sound, or maybe a Harley motorcycle sound, no wait, the Harley sound is copyrighted, damm! Who gets to copyright the required EV car sound? Chevron?
Dave
Victoria BC Canada
Noise makers *?!!@#!!
There is documentary evidence that urban noise contributes to childhood stress and in extreme cases to hearing loss and all manner of other nasties. Quietening our cities is one of the big benefits of EVs. I do trust that idiotic notion is quickly buried
The newest millionaire will be the one who develops an iPhone app that lets you download your EV “noisemaker” sound. Personally, if they forced me to make my EV make a sound, I will record a toilet flushing….
I think this whole discussion is confusing the concepts of “Cell Balancing” with “Secondary Battery Protection”. What kills batteries (of any chemistry) is either charging them above their maximum rating, or discharging them below their minimum rating. There are several devices specifically designed to handle this – for example the following Seiko parts are used extensively in Lion and LiFePO4 battery protection circuits (i.e. one per cell) :
http://datasheet.sii-ic.com/en/battery_protection/S8261_E.pdf
The CO output is used to disconnect the charging source during overcharge, and the DO output is used to disconnect the load during discharge. This is “secondary battery protection”. “Primary battery protection” is usually a PPTC (Positive Polymeric Temperature Coefficient) device attached to each cell by the cell manufacturer.
“Cell Balancing” on the other hand, whether active or passive, is a mechanism to allow
a more uniform distribution of charge across all cells of the battery pack.
You absolutely need “Secondary Battery Protection”, however “Cell Balancing” is optional.
Yes, I agree that “Passive Cell Balancing”
using shunts can be dangerous if the shunts are not heat-sinked properly, that is a design error in my opinion.
I hate the term “Battery Management System” –
it doesn’t really indicate what is acutally going on…
😉 my two cents, anyway…
Moxbox, you’re creating confusion where there isn’t any.
You differentiate “Secondary Battery Protection” from “Cell Balancing” and then declare that “You absolutely need ‘Secondary Battery Protection.'”
This is exactly wrong. You just can’t get your mind around it. If you slightly undercharge a pack of these large format prismatic cells, and never overdischarge it, you simply don’t need an accessory “secondary system” to shut off the charger. The expense is wasted and the complexity creates the risk of cell damage and fire.
Think of it this way: These prismatic (Thundersky, CALB, etc.) cells have been available for about 2 years and have been installed in, what, fifty cars? maybe 100? No way its more than that worldwide. To date, there is NOT ONE documented fire in any of the cars without a “BMS” of any flavor you want to call it.
Moreover, there is NOT ONE ruined cell reported in the admittedly small fleet that wasn’t damaged from a BMS, an instrumentation load, an accessory wiring fault or botched charging scheme. That’s what kills batteries, not “spontaneous imbalance” conditions.
It is indeed a hard thing to get with, especially if you actually already believe that “You absolutely need “Secondary Battery Protection”,” without having any experience with the large batteries, the systems themselves, and the automotive environment.
This last bit is the most important. I know very little about electronics, but I know a lot about cars, and I haven’t seen ANY electronics that didn’t come from an OEM that were really up to the environment: Huge temperature fluctuation. Vibration. Shock loads. Humidity. Water. Dirt. EMF. UV. Its an awful place. A bare PCB with wires soldered to it is simply inappropriate for this application.
Once you understand that you really DON’T need a “BMS” to “protect” your battery pack, then adding one is just shoveling risks and points of failure into the car.
Really.
The data from how these batteries are actually being used around the world is starting to bear this out.
TomA
Well said , all above. My wife has a condition it is called -anosmia- the inability to smell. If you emit a poisonous cloud to warn the hearing impaired…
Oh, we already do that.
This bill is on the presidents desk.
JMS
Chelsea Sexton has done some good work trying to stop this. I wrote my senators and congressmen trying to stop this but all three voted for the bill. None will receive my vote their next election.
http://evchels.wordpress.com/2010/08/06/quietly-making-noise/
http://evchels.wordpress.com/2009/10/02/blind-leading-the-blind/
http://green.autoblog.com/2010/06/23/chelsea-sexton-were-losing-sight-of-reason-in-the-debate-over/
http://www.greencarreports.com/blog/1047485_sounds-for-silent-evs-solving-a-problem-that-may-not-exist
http://www.greencarreports.com/blog/1047587_sounds-for-silent-evs-more-data-same-result-not-needed
http://wheels.blogs.nytimes.com/2010/06/21/anti-noise-activists-oppose-sounds-for-electric-cars/
The car on the parking lot was not an EV, but just a normal Mercedes CLS.
Martin.
Hi!
I live in Norway and has followed with this electric vehicle fire. There are many errors here from Jack.
The car was built not by the Danish company. This is a car that was built privately by a man from the Netherlands. The Danish company helped the Dutch man to sell the car to a Norwegian customer.
The owner of the vehicle believes that the fire started in the charging cable. He had used a cable that did not fit the Norwegian standard. The fire is still to investigation
I do not like BMS but do not like to use a case of BMS fire when you do not know yet if it was BMS who started the fire. We’ll wait until the investigation has found the cause of fire.
Øyvind Holst
2EL
Mr. Holst:
You just investigate your ass off. I like all that. But a nonstandard shorted charging cable will not start such a fire. These cells were grossly overcharged. The one car has TWO Brusa chargers and they just don’t overcharge anything. However, they are very BMS friendly. You can connect them to a BMS via CAN bus and they will do anything they are told, including burning your car to the ground apparently.
So you investigate and see what actually happened, and get me all straightened out on this stuff. I can build an adapter cable with all three wires CONNECTED together and I couldn’t get it to set a can of gasoline on fire before blowing the breaker. If it had a highly resistive connection, it MIGHT melt. But it wouldn’t start a fire of such magnitude.
One of the things that DOES drive me crazy, is the inability to admit a mistake. This is going on with the LincVolt fire as well. They’re still “investigating” and making allusions to “human error”. Hell it’s ALL human error. But the batteries have to be GROSSLY overcharged to the point that the cells vent AND create enough heat to light off the vented electrolyte. They are’nt a “little bit” overcharged. They’re not “on the wrong setting.” And all but the most crude Lester 1957 model chargers are pretty good about shutting down if anything goes awry.
UNLESS they are controlled by a “BMS”. A BMS designed to PROTECT your cell pack. That is almost the ONLY way you can melt down a battery and start such a catastrophic fire. Well, actually if you just hook it up to a simple charger such as a Manzanita and don’t SET a cutoff, that will do it as well, and I have.
So you just investigate that cord to death. Look for ANYTHING you can find that won’t point to the design of the vehicle itself, because the belief system is just SO strong that you HAVE to have a BMS for SAFETY (if only one child is saved….).
I don’t have to be there. I don’t need anything but the photo. Because I already know exactly how to make it happen – I’ve done it. Your little adapter cord won’t toast a marshmallow even at 400v 3 phase.
In fact, you pretty much have to CONVINCE the wall source that everything is ok in order to do this.
Jack Rickard
I cannot believe they’re making EVs add noise devices so people hear them. When I joined the DADRL (http://www.lightsout.org/) I wrote in their comment section that if the Gov thought daytime running lights would prevent accidents, the next step would be to require everyone to run our car horn all the time so people know you were coming. I never thought my idiotic comment would become reality.
JR
A response to Øyvind Holst
I also followed this story in the media, when it happened, and I wrote about it in two comments to the LincVolt blog entry.
What was first reported by the press, that the car belongs to a man from the Netherlands, seems to be wrong, it has since been reported that the car belongs to the founder of the company A Future EV, Søren O. Ekelund who was also driving the car, and had connected it to the power outlet on the ferry.
I have not contacted mr. Ekelund, so I can not be completely sure who was the owner of the car, and what A Future EV writes on theire own website “A Nissan Qashqai, converted to electric vehicle like the Qashqai Electric we currently produce” Can be understood both ways.
The ferry have fire extinguishing using sprinklers, and this was probably the reason that the fire did not spread more, and no harm was done to the passengers on board. I am not an expert into fires and fire extinguishing, but if the fire had started outside of the car, I would think that the sprinklers could have put the fire out before the car had burned to the ground. This last part is speculation on my part.
Carsten
I, for one, would welcome a subtle sound to an EV when negotiating busy parking lots at slow speeds. People just don’t look around.
And as far as I’ve been able to discern, this is the type situation the legislation seeks to address.
What are all your opinions on what this means?
“I, for one, would welcome a subtle sound to an EV when negotiating busy parking lots at slow speeds. People just don’t look around.”
I think an additional horn button that produces a subtle sound instead of the loud startling sound of the regular horn is a good idea. It’s the operators responsibility to watch for pedestrians, not the pedestrians responsibility to listen for cars, and a subtle horn can aid in this communication. I believe this is how GM addressed the issue with the volt.
Turn up your stereo.
JRP3
“Turn up your stereo.”
My biggest complaint about this issue is from being the pedestrian rather than the driver. I’ve been driving EV’s for over 15 years without any problems. I don’t want to walk down the road with hundreds of cars whirring, chirping, and buzzing.
Did you notice that at the Nissan drive events where they had 15-20 cars going in and out of a parking lot for test drives the sound was disabled. It’s because when you have more than one of these cars sounding off at the same time it is really annoying.
Your politico’s are a set of idiots too! Imagine my shock. I wonder if they know what a horn is?
It does not matter how loud your car. If you start to reverse out of your parking slot at a supermarket.. Somebody WILL walk into your intended path. So I suggest the sound of loud squealing tyres accompanied by a blood curling scream and breaking bones, connected to the parking/proximity sensors. Not the brakes!! I’m a firm believer in Darwinism. Besides, they have no excuse in such a circumstance.
If I’m on the motorbike. They avoid me as if I’m prepared to commit murder. Must add, it’s not due to the noise but the fear mindset instilled into my potential victims.
At speed, (40+), the loudest thing on almost any car is radial tyres. That’s a hint. Who’s to know it’s on all the time?
Well, I for one love the loud horns.
I put them on everything I own. The best are the 1960s-1970s GM full-size horns. Damn Loud. Dirt cheap. They need a big fat relay, though…
I hate it when pedestrians wander into the street with there head in their… Nothing more fun than seeing them physically jump to the duo-tone blast. That’s what I’m after- to arrest their movement and get their full attention RIGHT NOW.
I actually put a set of these horns on a 308GTB. In that case people would wander in front of the car looking at it. Pedestrians swarm all around cars in NYC, and other drivers often need their attention refocused, so a good horn is essential.
You can’t have it both ways, guys. It is up to the driver not to run over the pedestrians. If they can’t hear you coming, you need to notice that and SCARE THE HELL OUT OF THEM while there is still time. Short of truck air horns, nothing does that like those big 12V scroll units. JC Whitney still sells them. Don’t forget the “big honking” relay…
TomA
That ferry fire.
Didn’t they try to put out the batteries with water? It seems to say so.
Reminds me of one of those TV video’s where some ‘heroic firefighters’ were attempting to put out a magnesium fire in a scrap yard with every water hose they could throw at it.
Now that would keep the peds at bay!
response to carstein
If you have recently read that the car was not owned by a man from the netherlands so it has not arrived in the Norwegian media. But it may be that you have read it in the Danish media?
Jack
I say nothing about that there was BMS who started the fire, I just refer what the driver of the car says. It may well be that it was the BMS who started the fire. And I completely agree with you that BMS is not the way to go. But I think there is extremely important not to go out with a statement about the cause of fire, before you know sure what it was.
It is written so much wrong about electric cars in the media and it is very important that we do not do the same. It is good that you go full out and say that BMS is dangerous but it is extremely important that you find cases where you know 110% that it was the BMS who started the fire.
But stand on Jack I think you have a very good website with lots of good info.
Holst
2EL
The girl j waking with the Ipod in her ears can’t hear a firetruck coming much alone a EV.
dhiller
Forced sounds, Lunacy. Seriously, were paying for these bozo lawmakers.
Jack, coming from a guy who just wants a safe, fun electric car, thanks for carrying this BMS torch.
Tom A, would you be one in the same whose building the lightweight trike?
I have to agree with Jack. The input is fused or breaker and if you melt the cables that’s about it. That’s all it would do and it would do this fairly early on since its at the bulk charge cycle or constant current. If it happened early in the morning though. Its been running fine all night long without incendent and should now be reaching the point where it should be going to constant voltage. If the charger never gets the signal to reduce the current this is where you have burning behavior that effects the entire pack placed throughout the car. Lets look at this honestly. I have burned wires before in a car and it doesn’t look like this.
As for the noise makers it doesn’t really surprise my. This country is way too safety consensus we are always trying to save us from ourselves and dumb us down in the process. Why do we really need to save lives with seat belts and helmet laws? There are too many of us anyway and the earth could use a break. Yea it hurts when people die but its part of living. Just enjoy it while you are here and do as little environmental impact as possible.
Oh and BTW Merry Christmas everyone may you all have LIFEPO4 in your stockings.
Thanks, Jim
I’ve found a BMS that works!
http://www.hospitalathome.gr/PagesEnglish/IATRIKAen/BIOIATRIKIen/BmsEN.htm
Merry Christmas everyone.
@Tom:
Yep, I am one and the same.
The Moonray is behind schedule, (almost complete in 1:3 scale, but there’s no room to work on the parts I’ve accumulated in the garage) and it may be interrupted for another build (4 wheeler) anyway this spring.
Let me take an irrational guess- are you todayican the trikemaster from Florida?
If so, Merry Christmas, Tom B.
TomA
Yes sir Tom A BMS FREE 1 day at a time 🙂
Building a 96v 2 seater hybrid, hit me on one of the haunts or email me 🙂
Hi Jack & Brian,
For all the work you did this year and all the information you shared, thank you very much indeed. A very Merry Christmas and a happy new year!
JohnM
Merry Christmas Jack & Brian!! Your our Hero’s!!
we live from week to week to see you shows!
It will be an interesting day when owners of lithium packs find that their per mile cost of using lithium is right up there with the cost of driving a Ferrari(excluding purchase price) when their packs do not last as long as they expected. Sadly they won’t even know why, since they didn’t invest in anything that gives them information about their pack as they charge or drive. They figure using a volt meter on each cell while the vehicle sits still, is good enough. Sadly this has always been the common EV wisdom.
If a BMS is not the answer, then how do you find out when something is wrong with a cell when things do, an will, go wrong? When folks like Jack preach without any data, that a BMS is the source for fires, and that a BMS is not a requirement for an electric vehicle. I found that these are also the same folks with very few actual miles on their packs, and therefore real experience. Spending money does not equal experience. As packs age, the cells diverge in voltage and capacity, regardless of the chemistry chosen.
I have found that those who invest themselves in not using a reliable BMS, are also are the types that have a strong tendency to ‘believe’ in things rather than to know things using data and facts.
Again, it will cost all of the folks who follow Jack’s preaching, dearly some day when they find that their lithium packs have a high cost per mile due to early failure. Then they will speculate as to the cause, since there won’t be any data about cells with problems.
There are so few electric vehicles in the world, that they get a disproportionally high amount of press from ignorant authors. This is a common theme in any technology based subject. 80% of ‘information’ in the EV community is not based on any test data. Just something read in a forum or on a website.
The biggest issue with those that supply BMS systems, is their lack of real world experience. That lack of experience always shows up when the BMS system starts to malfunction for ‘mysterious’ reasons. Electric vehicles are a very powerful source of EMI. The experienced industrial designer knows this and incorporates correct design parameters into the design so EMI is not a factor. I have found EMI to be what sorts the amateurs from the pro’s in the BMS design world. Unfortunately there are far more amateurs, even in big companies, than there are seasoned BMS design pro’s. Because everyone with a soldering iron considers themselves qualified to design and sell BMS hardware.
Jack, I really like your videos for their entertainment value, all be it, they are getting a bit long, and some of what you offer the EV community. But you are a preacher of beliefs, not of facts. You will personally contribute to the early death of many battery packs with your belief based religion that so many subscribe too. Since most people don’t know the difference between electric vehicle facts and fiction, the only thing that will eventually get their attention, is the huge cost of the early demise of their expensive battery packs. You won’t have this problem Jack since you can afford it. But most cannot.
Mike:
For SOME reason Google flagged your post as SPAM. A little history here???? I overrode it manually to post your flame.
No FACTS in your post, just chanting the mantra. Sounds like you are involved in BMS design since everyone else is an amateur.
Oddly, I agree with you to a point. EMI is a big deal, and entirely ignored in the EV design community. They get it working in the lab and garage, and take off down the road spewing more than an AM radio station and don’t understand why the stuff isn’t working right.
But your whole post is absurd. We are the ONLY ones talking facts, demonstrating cell parameters, and showing how to burn up cells on purpose. And as for our cars, we’re RETIRING packs that have served for 2 years and thousands of miles because they are OBSOLETE. We’re actually going to reuse one entire pack on ANOTHER CAR.
You cite nothing. You quote nothing. And you provide NO information other than the tired old “You’ll be Sorreee….” allusion that is the meat and potatoes of people selling BMS.
At this point, you’re OUTED. Toto has pulled the curtain away, and screeching into the microphone to “Pay no attention to that man behind the curtain…” doesn’t precisely make you a wizard.
If you believe in BMS, please be honest about it and when the fire occurs, be man enough to return – with photos.
Jack RIckard
mikep_95133:
So, what major manufacturer has used a BMS?
Toyota’s RAV4-EV perchance?
http://www.youtube.com/watch?v=4xul-H4HsMw
“Uploader Comments (eaaev)
Howdy,
Update on the odometer.
I watched it roll past 111,111.1 miles a few months ago.
Now I’m at almost 115,000 miles with the original batteries.
Maybe LiPo batteries can do that now, but this car was built in 2002 and the lithium batteries at that time had poor life spans……….”.
Hmmmm. Maybe I should add more. 300wh/mile @ 10c/KWH = 3c/mile.
0.03*115,000 gives a total “fuel cost” of $3450 at todays prices.
Using fuel: 25mpg*115,000miles @ $3.20/US gal is $14720.
Saving him $11,270 in his eight years. Whilst having a superior drive, cheaper servicing, No fuel queueing blah, blah.
BMS? ok… What are these about then?
http://www.ev-power.eu/index.php?p=p_48&sName=lifeypo4-batteries-%2812v%29
The specs say they can be a direct replacement for your AGM starter motor battery.
Jack is right. This argument is over.
Jack: When I posted it gave me an error that said ‘too long’. Thanks for fixing it and posting it too.
I have tinkered with BMS designs. Built several. But I have many years of professional EMI experience. I go around and find the real issues with owners hardware with an EMI probe and an E-field probe attached to a scope. Guessing doesn’t suit me. No I’m not selling a BMS or representing anyone who does. I’ve just observed many years of EV owners ruining packs and not knowing why. The joke around here is, “So what did your BMS tell you?” as they smoke yet another pack. Of course without a BMS, there is no data as to what went wrong or what was going wrong. Only dead or dying cells. It gets old to see people selling EV’s due to the tiring expense of constantly replacing battery packs. I’m deep into the EV community in Silicon Valley. I see this constantly. Your problem Jack is that you can afford to buy pack after pack. Most in the EV community cannot. And because you preach not from experience with a BMS, but from conjecture, I stand up and cry foul. You have made comments suggesting that EV fires are related to the BMS. Yet the reports don’t mention that, ever. So I’d like to read what you read about the BMS being at fault, ever.
Who uses BMS systems? AC Propulsion is my gold standard. They have had a BMS in everything they have ever built from 15 years ago to now. I have worked on ACP cars and several other vendors as well. Even their oldest BMS design works flawlessly as it passes into it’s 17th year of operation. ACP is the grand master of EV’s. Their understanding goes far deeper than any other mfr on the planet. Even Tesla had to license from them. I’m lucky enough to know them and to have them share their knowledge and expertise with me. Their engineering and execution examples driving around for the past 17 years are not matched by anyone then or now. They use to get 30k miles from agm lead acid packs due to their BMS.
If you can furnish where you read about those mfr’s that are moving away from BMS hardware, I’d sure like to read about it.
As for the RAV4 from Toyota. It’s a home run! To date, it is my choice for the very best EV ever built. Period. No they didn’t use a BMS. But they did knew something about nimh that most didn’t. That is can be slow charged for hours on end and not ever get overheated or overcharged, but completely equalized. Almost like old flooded lead acid batteries. The nimh cells on the RAV4 are sealed flooded cells. This is why they can be equalized. Flooded nicads are the same way. They can take an overcharge long term, as long as they never get hot. These very specific uses of flooded nimh cells, make their system BMS free. Nobody has ever done that before or after and had packs last over 200k miles like the RAV’s do that are owned by Southern California Edison. Well, Ford and Chrysler used the same cells in their mid 90’s EV’s to the same effect. This does not make it possible for any other chemistry able to survive without a BMS. I have watch 10’s of thousands of dollars in packs go up in smoke from not watching over the pack with decent hardware.
Jack, you stated that you have a pack that was obsoleted? What the heck does that mean? Really? Packs are either working or dead. They don’t go out of fashion! What I challenge you to do, is track the mileage on every pack you own, publish it, and see how long they last. That’s where the truth will always be, is with the mileage. Then folks can see how much the cost per mile of going without a BMS will really cost them. I cannot find any mileage data from you on any of your packs. Or efficiency numbers on any of your vehicles in watt-hours per mile.
Yes, you and your crew have shown lots of video on how things worked and didn’t to everyone’s benefit. You do that a lot. But when it comes to a BMS, you are guessing.
Bullshit and flim flam Mike. You’re what’s killing cars. No data. Nothing but “vast experience” vaguely alluded to. We’ve put out our mileage, our calendar, and our cars weekly for nearly two years. You put out bullshit.
You’re NOT a professional anything. You’re a hangers on and represent the very worst of the old guard who are misleading hundreds of people into daily disaster.
What “obsolete” means is I can replace my pack with better batteries, get further range and better performance. We can actually resuse the pack on a vehicle of lesser importance, to me anyway, and it will continue indefinitely – totally BMS free.
As to AC propulsion, we spoke with them at length nearly two years ago and cannot confirm your experience. In fact, we found them less than knowledgeable about their own product. We’ve SCREWED UP a Mini COoper twice now that in both cases outperforms the BMW version, which uses the AC Propulsion system, on ALL fronts – speed, range, acceleration.
In short Mike, your a poseur, and the most dangerous sort of poseur.
Jack Rickard
What would you, specifically, like data on from me, Jack?
Here is what I asked you for, have not recieved or cannot find:
1. Watt-hours per mile on your vehicles.
2. Miles put on each BMS-less pack.
A new request: Acceleration/speed data on your Mini Cooper so I can compare it to the ACP Mini Cooper. 0-60mph times? Top speed?
I am still waiting for articles/results from you that any car fire to date, has been the fault of a BMS. Still waiting….
mike, a little searching on your behalf would have found this post
http://jackrickard.blogspot.com/2010/08/new-instrumentation-for-speedster.html
which shows those oh-so-elusive (as you claim) Watt-hours per mile
oh, but yet you say ack never published such figures?
well – from what I see, *someone* is talking out their ass there, and well, as I’ve just proven that jack DID publish such data – guess that must mean it’s you
as for the other stuff, it’s there too
but I doubt you’ll even bother to look for it as you dont want to actually LEARN things, nor really know the answers, you just want to troll and push BMS
(oh and as for the BMS causing a fire – how about you go back and check all of jacks previous stuff for his own PERSONAL EXPERIENCE when he actually tried a BMS on his speedster (as he thought if everyone is saying he needs a BMS, then he must be wrong in thinking he doesnt) – and almost had his car burn down directly because of it) (though I’m sure even if you see the direct facts – you still wont believe them)
Mr. Anonymous,
In the url you have furnished, Jack talks about the AC kwh’s used to recharge his vehicle divided by the miles driven. The problem with this is that it takes the entire charger’s efficiency, faraday efficiency, and pack variables, into the equation, which are a huge set of variables. In fact so huge that Jack’s drive showed that regen made the car less efficient. Other drivers showed a modest gain. That’s the kind of info that needs greater scrutiny as regen brings far more to the table than Jack and his tests show. But since his car is not instrumented for measuring watt-hours as he drives, he’ll never have accurate data on just the vehicle. I asked for the efficiency of the vehicle, nothing else.
Sometimes the efficiency of the vehicle only, is referred to as dc efficiency. He furnished AC efficiency. While helpful in some regards, warm batteries of all chemistry’s hold more energy than cold batteries. Peukert’s constant makes a difference due to the weight of the drivers right foot. Yes even lithium can’t escape Peukert. That’s why his info on regen is seriously flawed. Too many varialbes. Had there been an E-meter or equivalent installed in the vehicle he’d have found the real measured value of regen. The RAV4’s, US Electricar’s, and ACP cars show between 20-40% gain with regen on versus off. I’ve measured and recorded this on several vehicles over a few years. This kind of data that Jack generates brings yet more false information into the EV community, that is already full with misinformation.
Jack having a BMS problem is not data for the claims he made about all of the other car fires being the fault of a BMS.
If you even care to, the National Renewable Energy Laboratory (NREL) has a couple of reports out on packs using and not using a BMS during charging. It’s great reading. If you can’t find it, let me know. They show conclusively the value of a BMS.
I will say that not all brands of BMS are ready for public consumption. But that does not deter the value of a BMS. Buyer beware.
Mike:
Quit it, or leave. You’re just thrashing about wildly. You know nothing of what we have discussed, and clearly nothing of which you speak. We did WEEKs of regen. It is not what you think. And we proved it. The stuff with the charger was because some OTHER jackass didn’t like just doing it with the instrumentation in the CAR, and wanted END TO END from the wall.
You are viewing snatches and grabs, coming to ridiculous conclusions, and attempting to post something implying you know something. You clearly don’t. You don’t have any data to contribute. And as best I can tell you don’t even have a point of view that holds water from the beginning of your own message to the end.
You’re still waiting for all this data? It all sounds like a bit of work for me, to repeat things we’ve already done, to satisfy your DEMAND for the information.
You know, we have a lot of viewers. And so we do get a lot of suggestions for tests and data. And as I can, I even try to work em in and deal with it as best we can. Often, we get very interesting suggestions and it is my privilege to devote the time and resources to try to discern just what IS bullshit from shoe polish in those cases. It’s led to some good shows and a learning experience for me as well.
When someone entirely unknown to us comes on here with rapid fire DEMANDS for this and DEMANDS for that, while making it abundantly clear they were too lazy to even LOOK at any of the prior videos, many of which address EXACTLY what they are touting, and in this case from a really BAD case of EXTREME ignorance – confused by a claim that indeed they have some EXPERTISE in the area, I just don’t know how to deal with it.
So you just keep on waiting for that data Mr. Mike. I’m developing a case of “MIke Fright Deafness” in this particular case. I probably do know the answer, and have kind of lost interest in the question in your case.
I’m supposed to be the biggest asshole around these parts. It would appear you’re trying to horn in on my gig for that position?
Jack Rickard
You deleted my post Jack. You win….
I did NOT delete your post Mike. I already won years before you showed up.
Your post is probably in the Google spam-lot. This happens to people who keep getting reported to Google for spam. Clearly you have a history somewhere. If i get time, and it is in there, I’ll try to dig it out.
You clearly have some issues going on. They’re not mine. They don’t belong to me. And I don’t have to deal with them for you.
Jack Rickard
Once i forgot the battery in the garage getting charged for one and half day, nothing happen the battery was charged and the charger was still on but not charging, I agree that chargers on they own don’t start fires.
I’ve never been a spammer. So I don’t know why my post would be rejected by Google. In fact my account is with Google. I have to log in to Google make this post.
Here is the URL for the NREL report on equalizing a battery pack with a BMS and it’s importance. http://energy.ece.uiuc.edu/Balog/images/intelec02.pdf
Mike:
You keep digging up reports. I’ll keep digging up fires.
I don’t know who you are or what you’ve been. Google keeps tossing your messages into an area on the blog marked SPAM. That’s why they don’t appear. I keep digging them out. Your accusation that I “deleted” your messages was offensive and we’ll anxiously await your long, tedious, and overly detailed apology.
I still have not read or found a report from you or anyone else on how a BMS was at fault, anywhere, ever. In fact, this whole notion sounds like a myth busting episode in the works. I bet a catastrophic battery failure could be replicated on the bench. But it will always require a charger, with or without a BMS, in order to catch on fire. BMS failures usually result in a dead cell from over discharging in my experience.
Not sure about the spam. I will contact Google and ask them for some insight.
As for apologies, I guess we are both in for a long wait :).
@mikep_95133
The title to the article on the benefits of a BMS is titled “Life Extension Through Charge Equalization of Lead-Acid Batteries.” In case you haven’t noticed Jack has made it very clear and so have many others that he is talking specifically about LiFePO4 chemistry, not any other chemistry. That bit of information is VERY valuable to note and makes all the difference.
David
I’d like to to know how the battery chemistry makes any difference at all? The BMS cannot tell what chemistry it’s attached too.
And so viewers, you see the problem. A regular influx of absolute professional know it all lead acid heads, newly discovering LIFePo4 and spewing intelligence, goodness and light, in all directions – generally WITHOUT benefit of having seen any of our prior shows, nor bothering to determine even what the conversation is about.
Yes ,Mike. Your BMS can’t tell. All it can do is ignite things. It can’t help you. It can only burn down your freakin lead acid lake house.
Jack Rickard
Let me start off With a humble hats off to Jack, Brian, and crew for all the hard work to gather and produce the videos each week. It’s very much appreciated from this newbie to the EV scene. Keep the vids comming. My education is progressing!
As I’m doing a great deal of research into my own project it seemed only natural to find out what the battery manufacturers had to say about the use of BMS on the LiFePo4 Cells.
Interestingly enough this is what I found.
Before I lose anyone. This applies only to the LiFePo4 battery chemistry.
Winston Battery (formerly Thundersky)
http://www.thunder-sky.com/products_en.asp?fid=95&fid2=96
Clearly Winston Believes in “monitoring” the cells. But no where is there any mention of charge regulation of the cells.
Battery Test Videos – Winston Battery
http://www.thunder-sky.com/technical_en.asp?typeid=106
Even when shot and direct shorted the cells did vent. But never did the cells ignite into flames. And when exposed to an external flame. The case melted and burnt, as all plastic will do. But not as a direct failure of the cell.
I really found Calb to be the most telling of all!
Calb
http://en.calb.cn/ProductExhibitlist/&categoryid=dc37e6ff-4d2f-491f-ad3d-de8d514d8621&comp_stats=comp-FrontProductCategory_showTree-110.html
Lets call a spade what it is. The so called battery management systems (BMS) are nothing more than glorified battery charge regulators and as such have no place around a LiFePo4 battery pack. Who in there right mind would push maximum charge into a battery when the manufacturer directly states that overcharging will damage or destroy them.
Here is my battery management program.
1. Proper charging will a quality charger is a absolute must.
2. Monitoring is a matter of preference. We all would like to know what the batteries are doing.
Anything beyond this is a waste of time and money.
Take care of your batteries, and your batteries will take care of you.
Any Further Questions??
If you still can’t comprehend the facts. I have a few projects in mind that would gladly take good care of your LiFePo4 cells. Donations cheerfully accepted.
Thanks
Ghost
a.k.a Barry
As far as I can tell, people dismiss BMS at all levels, monitoring or management. As you pointed out Barry, CALB demonstrated use of monitoring. That’s very useful. But why would they waste their time monitoring any cell at all? Hmmm.
A BMS has at minimum of 2 functions. One as you mentioned Barry, one is charge regulation. Another is LVC or low voltage cutoff. Yet another is high voltage cutoff. There are even more. When a cell gets to it’s minimum or maximum safe operational voltage, how would the operator or even the charger, know that, if he was not told by some kind of BMS? The charger or driver can only see the entire pack, not each individual battery or cell. It’s been suggested that the lithium cells have such good production tolerances that they are very nearly, exactly the same. I agree. They sure
are most of the time. But especially when they are new. But not as they age.
In Jack’s video of 16July2010 during the demonstration of discharging 100ah cells at 400 amps, one of the cells was significantly damaged. None of the cells under test were being monitored for voltage individually. Had they all been monitored during the test, it would have shown a couple of things. One, that any battery discharged at such a high discharge rate will have a reduction in capacity. That observation was made by a man named Peukert over 100 years ago.
I’ve personally owned lead, nimh, lithium, and nicad chemistry’s in my vehicles. Lithium is only better in that is has more energy/power in a smaller and lighter package than the other chemistry’s. It still requires the same care and feeding as any other chemistry.
Don’t worry if you don’t know the differences in the various battery chemistry’s requirements. Your wallet will make it painfully clear.
Another great data point that Jack makes is in his 25June2010 video with Dr. Alex Smith. Jack has in the title of the video that it’s a BMS horror story. The good doctor of medical science, Dr. Smith, did make it clear at the beginning and end of his interview that the gross failures of his packs were due to packaging, not BMS. In fact he made zero references to the BMS being involved. The cells were not secured correctly to the chassis of the pack, nor were they electrically insulated from the chassis. All design flaws. But nothing from the good doctor about the BMS being involved. In fact Dr. Smith said he never got the chance to see the BMS in action. Yet Jack kept trying to make the point that it was a BMS related failure.
Shame on you Jack for trying to take real data and spinning it to fit your new anti-BMS religion.
Mike P – IIRC, the “packs” purchased by Dr Smith were supposed to have an integrated BMS and I would say that the whole fiasco illustrates Jacks point rather well.
The point that I understand Jack to be making is that the problem with BMS’s is less what they do when they are working right than what happens when they go wrong. A BMS built and installed to the same standards as an autoland system on an aircraft would be harmless, but a few circuit boards nailed into an aluminium case by people who demonstrably don’t understand the batteries well enough even to package them is an accident looking for a place to happen.
Hi John, Did you watch the 25june2010 video with Dr. Smith? I’ve warned folks here that not all BMS’s offered for sale are ready for prime time. We get to be their beta testers. So you and I see that clearly. But there is no excuse for not nailing down the mechanical properties of those packs. The lipoly/pouch/kokam type cells do require special and exact mechanical handling. That’s why I won’t use them. That mechanical design failure from the doctor’s explanation was clear. No shock and vibration testing was done on that pack, or as the doctor said, due diligence. I see every month at local EV meetings for years on end the destruction of lithium batteries from owners that had nothing installed to watch over them. An interactive, monitor only, BMS, at least gives the owner some info when a cell has a problem. I’ve seen some owners ignore their BMS’s warnings.
When someone in my area doesn’t want to install a BMS with their pack, I just tell them, you can pay now or pay later, but you will pay. All battery’s when new all act the same. But when they age just a little they start to diverge and cells get killed. Ask anyone that has owned an EV. EV owners that have had a few packs, know this all too well.
A BMS can be moved from one pack to the next as each pack wears out. So the investment will amortize better over time.
I have also found evtv very informative. Much more than any of the meetings I’ve been to. I am following Jack’s advice and going with lithium batteries and no bms. (1 day at a time)
Josh
@Mikep “I’d like to to know how the battery chemistry makes any difference at all? The BMS cannot tell what chemistry it’s attached too.”
The charging needs of the different chemistries are different. Lead acid batteries need to be top balanced to minimize the negative effects of undercharging. LiFePO4 batteries have no negative effects to undercharging they actually have a positive effect, longer cycle life. If you watch professor Jay Whitacre’s talk (http://www.ri.cmu.edu/video_view.html?video_id=60&menu_id=387) which Jack also posted it is very clear Whitacre says. Cell level BMS of any sort isn’t worth the costs. He very plainly says to do string level management and every 6 months or so check the balance. His recommendation is to do this at the discharged end of the curve too. He mentions lead acid and the fact that it is “totally different” than LiFePO4. For what his audience is doing he recommends that they do cell level monitoring only because they are doing research and need the data.
As for more than just monitoring pack voltage and Ah a Lee Heart style Batt-Bridge with properly fused wires is really all that is needed. The probability of both halves of the pack voltage having the exact same problem to perfectly cancel out and be undetected is quite low. I conjecture that it is even lower than the probability that a cell level monitoring system will work perfectly for the entire pack’s life or several pack’s lives.
MIKEP,
What brand of batteries and bms are you running on your ev? Does the club you belong to have a blog? I would be interested in reading some of your club members postings on bms and ev construction in general.
Randy
Josh: Please keep the world informed as to your success without a BMS.
Gizmo: The charging needs of each chemistry IS different, but not the BMS needs. The BMS reports if it’s a monitoring system or clamps if it’s a shunt system. Possibly both. But the needs for low voltage detection, high voltage detection, temp sensing, etc does not ever vary between chemistry’s. Once you’ve driven them all, in an EV, this becomes apparent.
CZTREE: I’ve had AGM’s, nimh, lithium, and nicads in my vehicle. A couple years ago a guy was offering some military nicads at a very good price. So I put them in. I have designed several of my own BMS’s, each for the various chemistry’s that required them. Since the nicads are suppose to be overcharged by design and also flattened occasionally, it would not have been fruitful to design one for them. So when I installed the nicad pack, the BMS came out. But as we speak, I have another lithium BMS design on the drawing board that I did not originate, but will modify it to suit my experience. I have an open source lithium BMS as well. I just build them for me.
We don’t have a blog. It would be useful, as we have several guys with lithium vehicles. I’ve seen lots of swollen and dead lithium cells. The owners never know when it happened. So the joke was born “What did your BMS tell you?”. I have tested many cells for people to determine how damaged they have gotten from either over charging or over discharging. So I know the results from not having a BMS first hand. I only ever overcharged 3 lithium cells to 4.5v. They lost 10% capacity instantly as I tested them on my constant current hardware. Making assumptions about lithium or any chemistry is something I just cannot afford.
Oh, I tried to watch the professor’s video, but it just won’t download completely. No problems with the HD videos however. I wonder if he owns and EV? Ownership seems to help separate fact from fiction.
Ownership indeed does separate fact from fiction, but only for sentients. If you want to find what you already believe, you pretty much can.
Jack Rickard
Gizmo: Thanks for that other link to the professors video. It finally downloaded completely. Very telling. At 1:09:23 the good professor said that at an engineering level the way to do it is to put a management circuit on every single cell. He totally agrees with the BMS concept. In the few minutes before this statement, he talks about the costs that consumers will bear of adding a BMS to consumer items. He thinks for cost reasons a BMS won’t work, not for any other reason!! By 1:09:45 the professor states that as long as your pack is very well matched, cell to cell, you don’t need a BMS. Guess what, even Jack states that the cells do not have the same capacity when brand new. If a cell mfr were to match your pack for you before shipping, the cost would go up substantially. At 1:09:54 he clearly states again, that the guys he’s speaking too with EV’s should run a BMS!!
At 1:10:50 the professor states that you would have to know that the resistance of each cell and it’s capacity are very close together in order to not require a BMS!!!
Overall his objection to a BMS is nothing other than consumers won’t like the added cost. He completely, clearly, and repeatedly states that he is for using a BMS several times.
Mike:
Please just go away. You are citing hypothetical answers to hypothetical questoins. The man spoke in clear terms in plain ENglish. In response to this debate, he gave me a quote to pass to any of you who were confused.
“BMS is a dumb idea for EV’s and you can quote me.”
Now here you are with a stopwatch, trying to explain to us that what I said he said, and what he said he said, is NOT what he said at all and you have the time marks to prove it?
You are truly a moron. You should not be allowed to play with electricity – or anything hot for that matter. Please leave us in peace and go spread your nonsense misinformation on one of the many online forums that just full of people who LOVE to type themselves smart. We already know the answers to the fairly trivial questions you are trying to resurrect. As an aside, we TRY to count the FIRES you guys cause – because it amuses us. Nothing else.
You are just in a forum over your head here, and need to go back to the sandbox where this debate has life.
I would suggest Endless Fear or perhaps DIYelectricjunk.
Jack Rickard
“BMS is a dumb idea for EV’s and you can quote me.”
Why did he say this? Do you consider cell monitoring without energy management a form of BMS?
J. Goldman: Monitoring is a part of a BMS. A proper monitoring system will interact with the charger to slow it down or shut it off during any problems that it detects. It will also be connected to the motor controller to slow it down or shut it off should there be a problem. That are monitors out there that just notify the driver, but without taking any action.
I’ve watched EV owners ignore that info and incur pack damage. You literally get what you pay for. With the advent of EV’s, again, we are now in an yet another age of snake oil. If you are in doubt about what to buy, ask EV owners that do have them. They can usually point to the high and low points of the brand of BMS they own.
“BMS is a dumb idea for EV’s and you can quote me.”
That statement clearly contradicts what he said in the video several times. That hurts the professors credibility. I wonder what kind of EV the professor drives and maintains?
Thanks you for the videos Jack. That’s a terrific amount of work. The education I’m receiving from you in HD, is priceless.
If some people type themselves smart as you’ve said so many time, are there people that can video themselves smart as well?
Hey Jack, do you still have those A123 cells? I’m in the market for some. They will make a nice light, low impedance pack for my vehicle. How much would you ask for them with and without shipping. Thanks.
I think I’ve got about 500 of them laying around here still in the original boxes. If you take em all, you can have them for $10 each. The shipping is the shipping, whatever it is.
Jack
No, Mike, it contradicts what you HEARD him say in the video. And that’s because that’s what you WANT to hear. This is the problem with you holy roller amateur experts. You get a belief system going and NO AMOUNT of facts, experience, or say so is ever going to move you because you SEE what you want to SEE, hear what you want to HEAR, and explain everything else away as anomaly.
You should’t be allowed to play with a flashlight with more than 2 D cells -even in broad daylight.
Now you cited me chapter and verse where you HEARD the man say what you wanted him to say. I happen to know he said nothing of the kind and his presentation and speaking abilities are quite good. He happens to know what he said as well. And because a couple of you guys INSISTED that he said something else, he posed a statement for quotation that is dumbed down even to your level. You can’t misinterpret it, reinterpret it, or misconstrue it because it is cunningly phrased for the benefit of morons.
BMS is a dumb idea for EVs.
Now I’ve told you its a dumb idea, he’s told you its a dumb idea, but they are YOUR batteries. Do what you like. The problem is, when you burn your house down around you, it will cause regulation for the rest of us, a bad image for these perfectly innocent and totally harmless batteries, and just a lot of grief growing out of a handful of BMS adherents, usually vendors, or worse self-styled home designers such as yourself.
You believe you know something, and search for clues to support it, with EV fires erupting all around you the whole time from these ill advised, poorly designed, BMS’s from hell.
Jack Rickard
With all the folks using BMS, and all the claims that they find bad cells through the use of BMS, can someone point me to a well documented case of somebody who measured the capacity of their cells, installed a BMS to monitor them, and the BMS found a problem and they were able to take that cell out of service before it caused a problem.
This assumes that the pack was never over-discharged (OD), and never over-charged (OC). I’ve not come across a single case of someone claiming that their BMS found a bad cell when the owner never abused the pack.
One view is that if you never OC or OD a pack, and you have reasonably matched cells (not perfectly matched). The pack can be used without a BMS. The counter to this was that unless they are perfectly matched they will drift apart, and a BMS will detect this and save your cells.
In my experience (not much, just forum searches), the only cells that have been removed from packs happened when the pack was OC or OD. The owners would know about this event with or without the BMS. If somebody could point me to a case otherwise, I’d like to read about it. Thanks.
@mikep_95133: Glad the other video link worked for you. I took the video to our LCEVA meeting this week. It was very clear, especially watching it the second time, that Jay was talking to the group doing testing on their EV and so to collect data they did need some sort of BMS system. He clearly said that for what they are doing they need a BMS. They are not a typical DIY building an EV. That is the difference between telling them they need a BMS and telling Jack in a PM that “”BMS is a dumb idea for EV’s and you can quote me.”
IIRC, you pointed out earlier the need to properly design and build a BMS and that there are a bunch of lousy ones out there. Beyond the building of it, it needs to be installed properly. I went with what I feel is a better/safer BMS than most DIY people are going to use. After studying the characteristics of LiFePO4, trying to get the truth about them, and gaining some experience with them I think the financial risk would have been lower had I gone with a simple circuit to compare the voltage of each half of my pack and take action if the difference was too great. It would have meant that I have fewer wires, only 3 sense wires, to the pack, which could short out and that I could have bought 3 pairs of replacement cells (2p20s pack) and still spent less than I did on my BMS. Naturally, time will tell.
How many fires have been caused by a faulty BMS related issue and how many have been caused because a BMS was not installed? I don’t know the answer but I would like to know. A damaged cell with no BMS and no fire sure sounds safer to me than a BMS and a fire.
Oh, and am I to assume that when you said that a BMS doesn’t care what chemistry the batteries are that you weren’t talking about their “trigger” values for temp, voltage, etc.?
Palmer, your question is the reason I think that a simple 3 wire voltage sense circuit to compare each half of the pack would be ample. With my battery pack down to 2 degrees C I could get my BMS to sound a low voltage alarm even with a full pack. If I had voltage comparison of each half of the pack I could have seen if one cell was the culprit. The average vpc was fine so I didn’t worry about it but I still would have liked to know if there were weak cells. I’m planning on building such a circuit to use in addition to my BMS. Maybe I’ll be able to answer your question. I want to know too so hopefully someone knows of some documentation that addresses it.
Palmer_md: Not all EV folks are on the web documenting their experience. I know I beg everyone around me to put it on a website somewhere. There are lots of examples on EndlessSphere of guys having their BMS detecting low cells etc. Ask anyone that owns an SC Propulsion vehicle. They put a bms on every car for the past 17 years. Zero fires and the longest pack lives in all of EV history.
Gizmo: Cells installed in cars is the harshest environment a pack can face. Having 40, 50 or even 100 cells and not know anything about them is making assumptions. With that many cells, you cannot tell by pack voltage if one or even 3 of them has a problem. Comparing 1/2 pack voltages is just a losing proposition. Don’t let the complexity of the BMS’s you look at steer you away from getting one for each cell. There are no shortcuts. Do the math of how many miles you will have to drive on your pack to make it financially worth it. Do you think you can go all of those miles without knowing what each cell is doing? The very way people install their cells in their vehicles causes them to diverge in capacity and state of charge.
There is zero documented evidence that a BMS had anything to do with any EV fire. In fact, you’ll notice one commonality among fires, the charger was running. Chargers fail every day! Assuming that a pack is perfect is the assumption a charger has to make in order to do it’s job blindly without a BMS. I’m around the most EV intensive place on earth. Chargers are not reliable as the only source of info about a pack’s charge levels.
Mike:
You keep telling on yourself. If you have a 17 year history with LiFePo4 cells, tell us more. They first became available where we could buy them in 2007. You are mindlessly carrying lead acid thinking into a cell chemistry you apparently know NOTHING about.
There is NOTHING BUT documented evidence that BMS’s cause fires. CALB no longer even offers a BMS because of this. YOu can go ALL OF YOUR MILES without knowing the voltage of each cell, and in fact, in the case of LiFePo4, it is virtually USELESS INFORMATION. TOTALLY USELESS.
It means nothing while you are driving. The discharge curve is heroically flat and the sag voltage is quite signficant and quite dependent on current load. The only time it is even interesting is on charge and discharge.
Yes, there is a commonality on the fires – the charger was indeed running. In fact, it was running quite after the cells were fully charged, and in each case the fires happen in the wee hours of the morning after the charger SHOULD HAVE BEEN OFF. In EVERY case we have found, the charger was not in charge of shutting off. Control had been given over to the BMS.
In the case that THIS blog post is about, one of TWO fires with the same car manufacturer, they have TWO perfectly good Brusa chargers that are heroically good at measuring pack voltage and terminating the charge process. In both cases, the chargers aren’t allowed to. They are operated in CAN BUS mode and the Reap Systems BMS is totally in control of terminating the charge process, which it apparently does not do.
Comparing one half of the pack voltage to the other half is a “losing proposition”?????? Just cast that out there without a further thought at all. Ok. Now I’m convinced. Mikep thinks its a losing proposition, based on his misundertstanding of 17 years of no data on a BMS ever saving anything – with lead acid batteries. What are we to do with this level of thinking?
It is simply not sufficiently knowledgeable for this forum Mikep. As I said, I think you’ll do much better at Endless Fear. You’re just in way over your head here.
Jack Rickard
Jack, You make just as many assumptions about batteries as you do about me.
I still cannot find any proof of a BMS related fire, anywhere Jack. You have never posted one single word of proof from anywhere in your videos or blog. I’d love to read about it and now they reached that conclusion. It’s just not out there.
I don’t subscribe to beliefs, I only subscribe to data. Your fire and brimstone preaching is transparent.
Chargers are as stupid as can be. They only know if they are at a given voltage. They don’t have any idea if a cell goes bad. The charger cannot detect if a cell is over or under charging and adjust itself accordingly. The charger cannot know without being notified by a BMS, period.
AC Propulsion puts BMS systems in every car they ever built for the past 17 years. They have been using lithium with a BMS longer than anyone on the planet. The use monitoring and shunting. BTW they only bypass 300-400ma because their system throttles the charger or controller down when a cells flags a problem. Do you think a small company like that would enjoy not having to engineer all of that BMS hardware if it were not absolutely needed?? It costs big bucks! In fact they went all the way to shuttling charge from one cell to another for maximum efficiency, it was so important to them. Tesla had to license patents from AC Propulsion because ACP has been building EV’s, correctly, longer than any one else on the planet.
The ACP car near me has a 17 year old BMS that still works perfectly. Their lithium based systems have been around for years. These guys are the gold standard. What ever they decide, has many cars with thousands of miles for data.
If you want to discuss BMS product reliability, then we have some common ground. This is where I think your core issue really is. Just because something is labeled a BMS, doesn’t make it a reliable BMS. You only bought one as I recall and had a fit. How about trying something else?
Maybe a monitor only system?
Why is a BMS important?? When an EV owner packs the car with cells, they often put a portion up front and another portion in the back. The cells up front run cooler due to the air flow impacting the battery box and everything attached to it. The cells in the trunk never see any airflow. So they stay warmer. Each charge cycle the cooler cells have a little less capacity. So they get a little over charged. The cells that are warmer in the trunk stay about the same. Each charge cycle the difference between the front and rear pack just keeps adding up. Each time the cooler cells get slightly overcharged or even ever discharged due to less capacity, they are being damaged. Something has to watch over them or this leads to pack degradation. I fact this whole scenario happens when all of the cells are in the same
box too!
You started this whole anti-BMS campaign when your GEM lost cells. Did it ever occur to you that the GEM may have damaged the cells before you top balanced them??
You don’t do much in the way of capacity testing your pack’s cells.
That’s why you are surprised when a cell dies. Yes it’s a hell of a lot of work with 160-200ah cells. But what stops you from making an automated test station? You have the bench hardware. You have the skills. It just needs integration with a box that will tell it when to turn on and off. The back of your power supplies has a terminal block with enable
pins on it. It’s a no brainer to build.
I don’t care what you do with your cars and lithium cells Jack. I only care what you spew to your audience that doesn’t know your ‘facts’ from real facts. People are often cured of their beliefs when their wallet causes them serious pain.
Mike:
I’ve tried to be nice about this. YOUR A MORON. Your “facts” are not facts they’re not even pertinent misinformation. We capacity test our cells. We torture cells to death. You clearly know NOTHING of the GEM test and clearly either did not watch the video or are too freakin stupid to understand plain English. Rich Rudman said they HAD to be top balanced. So I top balanced them as an experiment and IMMEDIATELY demonstrated cell loss directly caused by TOP BALANCING.
We repeated the test THREE TIMES>
We then bottom balanced them. And drove the car to a complete STOP. Would not go further. No juice. Get it? Batteries FLAT. Won’t move. Put a charger on it and they all came up fine and the vehicle runs on those same cells a year later.
Those are FACTS. Done on video. For all to see. It doesn’t get any clearer than that.
Now how you interpret that or reinterpret it is of ZERO interest to me. We have no vested interest in battery management systems EITHER WAY. Clearly you do. But you’re in the wrong venue for it.
Jack RIckard
“So I top balanced them as an experiment and IMMEDIATELY demonstrated cell loss directly caused by TOP BALANCING.”
Wasn’t it you top balanced then immediately drove until the GEM stopped or the pack voltage meter indicated “empty” and the combination is what killed 1 or more cells? Top balancing and then leaving the cells alone didn’t cause the problem. Naturally at least two solutions could be used to eliminate the problem. One is a cell level monitoring system which adds its own set of issues and is what the various flavors of BMS systems are supposed to do. The other is the bottom balance method which has definitely fewer points of failure.
The data I haven’t seen is the probability of failure of the different points of failure over the life of a pack of LiFePO4 batteries. In addition to the probability data the risk of each point of failure has to be taken into account. For what is available to the average DIYer and most small conversion outfits a string level monitoring or maybe a 1/2 pack voltage comparison is the safest route and also looks like the least cost route too.
David Nelson
You are partly correct David. I did TOP BALANCE and then immediately drove the GEM, that is true enough. But did not drive it either to a stop nor until the pack voltage meter indicated empty.
I did drive it until the pack voltage meter indicated a relatively low value. And it points up a weakness in the cells. Pack voltage is not much of an indicator until you reach about 95% DOD. It suddenly becomes an excellent indicator. The problem with using pack voltage at all is just that. At 80% DOD, which is where we really want to cease operation, we have almost no voltage indication that we are there.
By the time we are clearly declining – we are quite past 80%, in fact the point on the discharge curve where the voltage becomes useful is more like 95%.
The GEM features a relatively small number of cells in series as vehicle packs go – in this case 24 cells. By top balancing, I have grossly exacerbated the differences in cell capacity by concentrating those differences at the bottom of the discharge curve.
Despite it’s being a small NEV, the GEM is still a vehicle. And so to drive it at a relatively low 72volts, it necessarily uses relatively high current levels for its size – quite in excess of the 200 amps I have the vehicle metered for.
And this points up the central problem with top balancing. You are doing all the “balancing” with a relatively dangerous shunt circuit that both generates heat, AND uses negative temperature coefficient components to do this, and you are doing it at a fairly uninteresting current level of 10 to 25 amperes.
But at the bottom of the discharge curve, you are driving the car – ie 200 amperes. And things move along this curve much more rapidly at 200 amperees than at 15 amperes.
The result is that if ONE cell goes over the knee of the discharge curve and begins the voltage plunge down the vertical face of this curve, while the remaining cells remain cheerily producing current up on the flat part of the discharge curve, the lesser capacity or “weak” cell is driven to zero volts and ultimately into cell reversal in a matter of seconds, where this process would be more on the order of minutes at 14 amperes.
Conversely, if you bottom balance, inherently and by definition you are ensuring that all the cells reach a point well down the vertical wall of the end of the discharge curve (ie 2.85 volts) simultaneously.
And so as our least capacity cell takes the dive, the other cells are really quite similarly weakened in voltage and thus in current producing ability. The result is you can actually drive the GEM until it rolls to a stop. The cells will be quite low in voltage at this point, perhaps 2volts static. But none were driven into reversal and the solution is a very simple – charge the pack.
Of course bottom balancing does quite the opposite, it concentrates all the differences in capacity at the TOP of the discahrge curve. And so it is quite possible then to overcharge a specific cell of lower capacity. As this happens much more slowly, we have a much better chance of manually detecting this. But generally, the solution is even more simple. Just drop your charge voltage a bit. In the case of CALB cells, the book voltage is 3.60 volts. If we charge the pack to 3.50 volts on average, we will indeed have some cells at 3.6 or even 3.7volts. No harm done actually.
Other cells with larger capacity may not get fully charged at all – at 3.45 volts for example. Well, the problem is we were never going to t get more range than our least capacity cell any way. So it simply doesn’t matter how much the higher capacity cells are undercharged.
Jack Rickard
Furthermore, your cell at 3.45V doesn’t have much more energy to go before it is full any way. By my rough measurements the capacity between 3.45V to 4.00V is enough to accelerate my Gizmo from a stop to about 15mph. This is with a pack of 36 TS 100Ah in a 2p18s setup.
I think that what many, my self included, took issue with was that your statement ends with top balancing as the cause of killing cells. Whether intentional or not, it looks like you leave out part of the picture to support your statement. Maybe it should be that top balancing cells can lead to killing them quickly, either by a cell being reversed at the end of the SOC curve or by a BMS causing a fire.
I now have a 2p20s pack so I know what you mean about high currents. I pull about 225A at 35mph climbing my hill and ~125A at full throttle on the level doing 46-49mph. My charger does 15A max. I think the charging unattended is a concern for safety. If the top balancing BMS systems that are being used are heating up due to shunting all the time then they probably are not working like they should. When I used to top balance with my BMS boards I found that when I had the cutoff voltage set correctly on the charger that the shunting didn’t happen until the charger had already cut back to about 500mA. Even then there was only 2-5min that at least one board was shunting. This is only about 4mAh of energy into a 200Ah battery! If the BMS is shunting so much it over heats the charger is set to a too high of a voltage. Furthermore, the wire wound ceramic resistors I see on so many BMS boards look like great fire starters to me.
FWIW and another data point, I haven’t top balanced my pack for the last 150+ full charge cycles representing nearly 6200Ah and 2600 miles and the voltage at the end of charge has not been more than 0.081V between the two most extreme cells. This is charging to an average voltage of 3.485vpc. My pack will have been in my rig for 1 year on 18 Jan 2010 with over 5500 miles on it.
For those who are still on the fence about BMS or not, I’m going to build and install a 1/2 pack voltage comparison circuit but leave my BMS (which I’m not using to top balance any more) and see which one signals a cell getting out of range first. Why not take out the BMS boards? I’m a physicist and want the data. Obviously if the 1/2 pack voltage comparison shows a dieing cell before or at the same time as the BMS that is one more data point in favor of minimal string or 1/2 string monitoring.
I haven’t decided whether to bottom balance my top-balanced pack or not. The benefit of leaving it is for the data I will gather on pack divergence but I lose the benefit of not reversing a cell if I push the limits of the pack capacity.
David Nelson
David:
The shunt feature of top balancing is an obvious failure point because of the inherent negative temperature coefficient of the semiconductors used. In those early systems where this was placed on TOP of the battery cell, like the VoltBlochers, this was bad news. They could indeed start a fire but more likely simply drained cells to zero destroying them.
The main problem with BMS’s and fires is relying on them to terminate a charge. Both the Brusa and the Manzanita chargers can be set to terminate the charge automatically and do a more or less good job of it. The Manzanita has some special considerations in the way it measures voltage, but if you are aware of it, it’s not a problem.
The problem comes in when you TELL these chargers to go stupid and charge until further notice. That’s basically what an Elithion or REAP Systems BMS does. In the case of the Qashquai, they have the BMS send a signal to the Brusa over a CAN bus to instruct it to terminate the charge process.
The problem with this is actually software. Software crashes. And when it crashes, it doesn’t send any signals. ALL software crashes. I have a copy of Final Cut Pro that I can crash at will using a very simple two step process. This software is version 7.02 and has been released and in use for over a dozen years. I can duplicate this crash at will, and have reported it. It is reproducible. There have been two releases since and it has not been fixed.
If your microcontroller in your BMS crashes, it fails to send the CAN bus signal. You have already told your charger to “go stupid” and keep charging until it gets the terminate signal. So it does.
The only way to harden a system against such crashes is to build more systems and have them vote. For example, the Brusa should POLL at least TWO microcontrollers for a CONTINUE signal. Each of those microcontrollers should POLL the Brusa AND the other microcontroller. If ANY of the three detect ANY anomaly in ANY of the other two, they ALL command shut down.
This is the three man vote and it is a common means of building reliability into software driven systems. i didn’t invent this by the way. It is COMMONLY taught to FIRST year computer science students.
The guys designing these BMS systems apparently have never heard of it.
Why do I know the BMS is at fault? Because inherent in their design they cannot fail to be. These are amateurs designing systems that have profound real world consequences. And they are doing it poorly.
IT is NOT that the concept of a cell level BMS is inherently evil. I looked for one for two years. I gave up. The work that is out there is shoddy crap done by morons. It is dangerous, and it is burning cars to the ground.
Why don’t I just design one then? It is an arduous process and requires a LOT of work and testing. That’s why you have crap to choose from. If I set my head to it, it would take three years to get a working prototype I was confident in and two more years of testing before I would sell it to an innocent victim. Most of these guys designing these don’t even own electric cars.
Jack Rickard
Top balancing vs bottom balancing. I REPEAT and I REPEAT AGAIN. I DON’T BALANCE AT ALL!. The concept of “balancing” your cells is derived from Pb and NimHd chemistries. These cells have a shuttle charge carrier electrochemical process that causes them to self discharge. As a result, they do indeed “drift”.
LiFePo4 cells do not HAVE this “feature”. As a result, they do NOT “self discharge” at all in the normal meaning of the term. And they do NOT drift at all. IF you are engaged in a conversation with a BMS designer, and he refers to “cell drift” in the conversation, he knows NOTHING about LiFePo4 cells and above all do NOT use a BMS he has designed in any area where your car might see it. He simply does not know what he’s doing. Usually, the well intentioned result of trying to adapt a Pb BMS to LiFePo4 operation, ignorant of the fact that they are completely different animals.
And by the way, do NOT apply my comments re BMS to AGM or any Pb or NimHd application. It is apples and oranges in the REVERSE as well. Those cells NEED to be overcharged, and they NEED to be equalized. Ours not only do not, but suffer the procedure poorly.
I have GIVEN UP trying to come up with little demonstrations for you guys. From now on, I’ll say it. You can believe it. Or you can demand a refund for the video. It’s too much work to try to devise little experiments to illustrate basic concepts that can be Googled by anyone with a PC.
Bottom balance is simply a procedure to align cells so that IN THE EVENT that you overdischarge your cells, as we sometimes do, that the cells are not destroyed. By balancing them on the sheer wall of the discharge curve cliff, we ensure that ALL the cells arrive at the END of discharge at the same point at the same time. This causes the pack to quit producing current before it turns on itself and reverses a single cell – ruining it. I’ve DEMONSTRATED how to do this on camera. And I’ve demonstrated how to avoid it.
IF you don’t ever overdischarge your cells, you don’t need to do it at all. The capacity differences of the cells is roughly evenly split between top and bottom AS YOU RECEIVE THEM. It’s good enough.
If you HAVE top balanced, EVER, I would strongly advise you to BOTTOM BALANCE as a CORRECTIVE to this MISGUIDED and IGNORANT and potentially damaging procedure. This simply moves the point of disaster further down the discharge curve and gives you a little more headroom. That’s all. You MIGHT need it someday.
With careful AH counting, and let’s get real, you guys KNOW how far your car will go and what you are comfortable putting at risk. You CAN tell by voltage. You CAN tell by AH. ANd you CAN tell by the trip odometer for that matter. So just don’t overdischarge the cells.
We LIKE to do this. Because we learn from it. And we sometimes put it on video. Just driving the car, I cannot imagine risking a pack for a couple of miles range. It’s $8,000. And I hardly need a BMS to do this.
We’ve shown several ways to limp or disable the car so your daughter can use it. None involve a “BMS” per se.
Jack Rickard
Jack,
“Shuttle reaction”: That is what I was missing. I don’t know why I didn’t see it but it all makes sense now. It clicked when I read your second post in you Jan 9, 2011 blog. Jay Whitacre didn’t talk about it in his video and looking at the chemistry it isn’t there. Also, comparing the wall-to-wheel efficiency of my Gizmo going from Pb to LiFePO4 it is obvious that the “lossy” reaction isn’t in the LiFePO4 batteries. I went from 4miles/kWh with lead to ~6miles/kWh Lithium. Assuming the Li batteries are treated properly the only thing that could cause the cells to drift would be some mechanical failure some where such as a leak in the case or other physical damage. Either would be easily detected with minimal circuitry.
As for “self discharge” I think it is a misnomer for LiFePO4. The only discharge should be from conduction through things outside the cell like the atmosphere or anything that collects on the cell. This would not be self discharge but merely discharge. I’d bet that if your 15 month old cells had been stored out were dust and grime could collect on them that it would have been discharged more than it was but it probably still wouldn’t had been much unless you stored them exposed under your metal lathe.
Since my cells have been top balanced I think I’ll bottom balance them when the weather gets warmer. I don’t want to have a problem as the capacity diminishes and I’m still assuming 200Ah capacity. Since I’m keeping an end of charge voltage record based on battery # in my pack I can still see a trend with my “top balanced” data. Besides, it will be interesting to see really how out of balance this pack really is. I’ll report on my blog when I do this.
Thanks for clearing things up for me, Jack.
You’re quite welcome. If you notice, I repeat myself a bit and try to explain the same thing several different ways. I never know what part is going to “hit home” and we have a wide range of expertise among our viewers. This is the REAL reason the cell drift thing has always been bogus, but few know what a shuttle carrier is so it’s not an explanation I use much. For you it worked.
Yes, it IS a transition. The ones who struggle most are the ones who know the most, about Pb or Nimmies. I guess the part I fail to communicate adequately is these are NOT same chemistry different anode/cathode. They are ionic. After the SEI layer is set, there just really is not a medium for self discharge or drift.
Cells DO get out of balance, if you unbalance them. I’ve done it with Xantrex meters, Cell Log 8s meters, etc. Be very careful of any parasitic loads that drain one part of the pack without draining the rest. But left to their own devices, the “divergence” theory or the “cell drift” theory is pure unadulterated bullshit. There is no such thing with this chemistry because there cannot be.
Bottom balancing is the corrective for top balancing. Nothing more. It simply prevents one cell getting eaten by the others if it goes over the knee first – and thence into cell reversal. I’ve driven the original Speedster to a STOP – get this – accelerator floored and NO movement. Let the car rest five minutes, driven it ANOTHER half block to a stop. Did it AGAIN. ANd finally we hand pushed it into the garage.
NO CELL LOSS. I had six below a half volt. All recovered and apparently quite fully. If you top balance, you eat one and sometimes two.
I would recommend a bottom balance at 2.85 volts. Simply don’t overdischarge until then and you’ll be fine.
Jack Rickard
“I would recommend a bottom balance at 2.85 volts.”
I was wondering what I should use. I have a dimitri BMS board set to 3V for individually bottom balancing cells. Believe me I’ll stick around while it is working if I decide to use it. I felt that 3v was too high on the knee so was going to go at least to 2.9 but I’ll get as close to 2.85 as I can and then wire everything up in parallel and let it sit for a while to even things out.
David Nelson
We don’t even go that far David. We just take the pack down below 3 volts, adn use a 30 amp charger with some jumper cable clips. We just give a shot to all the lower voltage cells to get them back up to 3 volts. Then use the heater or some other load to bring the pack down a bit further and repeat – go to all the cells below 2.85 and bring them up.
Adding charge is just easier than bleeding charge with a resistor. If you have anythign from Dmitri, get it out of the car and the house.
Jack Rickard
a plain cheap Curtis controller has a ‘sound’ at low speeds… is that enough? It’s louder than my ICE Honda van exhaust at an idle.
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Seems like they keep working on this dumb law. I’m not sure where they got the statistics, but they look fabricated to me without any reference.
http://www.npr.org/sections/thetwo-way/2016/11/14/502082110/pump-up-the-sound-regulators-tell-makers-of-electric-and-hybrid-cars