We’ve built precisely two of the A123 modules of the third kind. I shouldn’t be excited over something we don’t REALLY know if it will work. And it IS risky. We’ve locked up 48 cells in urethane resin that can never be dug out again. If a single cell fails, we just tossed $1230 worth of cells out the window.
Of course, if a single foil fails in one of our normal prismatics, I suppose things start to go bad there as well.
So I’m thinking of it as a larger prismatic battery of 40volts and 75 Ah – car sized at 75 lbs.
The interesting thing is that it was designed by a landscaper from the North Coast of New South Wales, a battery guy from a small OEM in Lisbon Portugal, and neither of them have ever SEEN it before as the first assembly was in Cape Girardeau Missouri. ; And none of us even know each other beyond a brief introduction.
Michael Murray of New South Wales sent in the BLENDER animation we showed in last weeks episode. It was a direct embodiment of a connection scheme first described to us ny Celso Menaia of Lisbon. And we added a bit of aluminum as a heat sink and some Dascar Plastics RP-40 urethane casting resin. Actually about a gallon for each battery.
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I confess my heart was NOT in the module project initially. But something about the A123 cells kept nagging at me. Often, I know something is important by looking at it, but for some time I cannot come up with just WHY I know it is important, or important in what way. In that situation, I just keep fooling with it and at some point it will tell me.
What this does is open the door to smaller, lighter, cheaper battery packs for smaller, lighter, cheaper electric cars. And why is that important to someone building a $160,000 Cadillac Escalade Project? Well, there are a lot of viewers who are not going to build an Escalade. That’s reality.
And we hear from a lot of viewers that are definitely going to build SOMETHING ,but seem stuck in “PARK” awaiting the signal to go.
We have been dismissive of lead acid cars as being “Science Projects” but in reality, that level of expenditure seems doable for most people, while the $17,500 required to do it our way does not.
I’ve been curiously unsympathetic. An aluminum john boat on a trailer with a trolling motor runs over $18,000 new now. So I remain curiously unsympathetic. My heroes, the real pioneers, routinely put down two or three times that for a build and are moving the token forward to change the world.
But it is of course true that all of this happens faster at a lower price.
So let’s change the game. And that requires some different assumptions.
Let’s talk about range. The lead guys swear they get 40 to 50 miles on a charge. This is where I fault them first. It’s a barefaced lie. They do not.
They might get it in theory, but in reality, 30 or 35 miles might be the range of their FIRST test drive. ANd it goes down steadily from there to five or six miles two years later when they park it.
If we defined our battery as 120v and 75 Ah for 9000 wH, and 225 lbs, we could probably do 35-50 miles on a single charge REALLY. We would be a half TON lighter than lead. Instead of a two year life, we have potentially a 10 year life.
I believe you could build these modules for around $1400 each. Three would be $4200, which is very different from $8500 or $10,000.
And do you know what? Not only is range anxiety not an issue for me at 80 miles or 100 miles, but my wife has been driving a car with a 45 mile range for months now and it hasn’t been a problem yet. We charge more often, but she really does NOT drive more than 45 miles per day.
The trick is the power output. The A123 cells we have TESTED to 23C – that is they made 475 amps in front of me while I was watching – from a series of three single cells. Yowsers.
ANd that means that despite it being a weenie 9000 wH pack, it could put out 1850 amps or so. Which is nearly TWICE what a Soliton1 will do and over THREE TIMES what the Curtis 1238-7601 can do. So we get not only FULL performance and FULL acceleration, but with a 225 lb pack, I would say OVER full acceleration.
Better, if you build a car this way, with this modest “test pack” in it and it all works out for you, but you need more range, what level of effort do you imagine you would face in wiring in three more of these? Picture a single Saturday afternoon.
So we think demonstrating this might just open up the EV project concept to a LOT of people that are avidly watching our show, but not actually turning a wrench at the moment.
This egregiously long and boring episode shows you how. We omitted the resin casting at the end, which is no big thing and we can cover it next week. But all the important and hard parts are there. It is a good bit of work. They do not assemble themselves. But we think it is a good design. Testing will tell. Note A123’s own module is in recall as we speak. These things aren’t easy. ANd I’m really NOT a packaging engineer.
We’re also a little giddy with cash flow these days. In the past week, we’ve sold over a dozen sets of the battery strap kits. This is simply a 70mm braided strap for a CALB 100 or 180Ah cell, a Thundersky 160 Ah cell or SOME Thundersky 100 Ah cells. We also throw in two stainless M8 bolts and two zinc coated Nordlock washers – the combination that has worked SO very well for us in the past year or so. We mentioned we’d sell these at $7 each and we’ve moved about 1000 straps in the first week.
This is no big deal. It’s a small thing. But God is in the details. Battery connections are a quick way to a stranded car. And we’ve kind of worked out over time how to simply avoid that entirely. We were getting straps from Australia, and now we have to get them in a relatively huge quantity from China in order to have them. But we think they’re a huge improvement over the copper straps provided with the cells.
This is the longest show we’ve ever done. As Mark Twain said, I would have written a shorter letter, but I hadn’t the time.
The close ups and the green chroma key have strained our editing equipment and software to the very limits of what they can do.
Regards;
Jack Rickard
Jack:
I hope you are potting the cells with a plastic that can be dug out of the battery; if so, please keep me in mind for first dibs!
Here is the torrent file for the HD version of this weeks show:
http://w5lee.tonidoid.com/app/webshare/share/319034032/
Enjoy
Lad:
Not sure I follow the concept. We are potting the whole battery in a urethane casting resin. It is like a fly in amber. It would be a huge amount of work to dig anything out of it and it is doubtful a cell could be dug out without damage.
The concept is a bullet proof 40v 75 Ah module. The second prototype depicted in this video actually measured 77.75 Ah which I think is very good. It was fully bottom balanced at 2.78 volts. We charged it to 43 flat. It relaxed to 40 volts. I cast it in resin Saturday afternoon. It took a full 2 gallon kit of RP-40. And I overran the top a bit and had to dig out the terminals with a wire brush. But it’s kind of a thing of beauty.
We now have TWO of them. I do one more and we have enough to run one of the HPEVS systems.
Jack Rickard
Great Show! It is becoming the most anticipated show I watch…. (Yea I am a bit of a geek)
I grew up in machine shops (started working in one at 14 years old). I am a Mechanical and Electrical engineer and a fairly good programmer. If I can help in any way with you efforts, please let me know.
I wanted to let you guys know about these shim punches. It should make clean clear cuts in 1/2 the time of drilling. You can make the punch tooling out of Lexan. MSC and Enco (MSC owns ENCO) are a favorite supplier.
http://www1.mscdirect.com/eCommerce/NavigationServlet/Shim-Punch-Die-Set/_/N-77dsr?cm_re=Category-_-BodyLink-_-Shim+Punch+%26+Die+Set&Ntk=All_MSC&Ntt=shim+punch&Ntx=mode+matchallpartial&Nty=1&rawInput=shim+punch%C2%A2shim+punch
I really wish I had found this site a few weeks ago. I kick myself because I just sold (About two weeks ago) a 1968 Porsche 911L that I was going to restore. It would have been the perfect EV conversion at about 2,200lb. A co-worker really wanted it and I sold it to him in a moment of weakness (Ok A little bourbon was involved). I am now trying to find a Ford Model A to convert. I think it would be really cool. If any one has a lead on one, (Other than Ebay) please let me know:
jeff@cuttingedgesoftware.com
Also, I find this site to offer Electronic gadgets at prices better than Mouser, DigiKey or Newark:
http://www.jameco.com
P.S. When drilling it is a good idea to raise the bit every once in a while to break the chip so that you do not create those long spinning razor sharp chips. I have, unfortunately, had the horror of watching those spinning chips remove the flesh off of fingers and have the scars to prove it.
Take care and keep fighting the good fight…
Awesome progress! Can’t wait to build my own version.
The availability of these grey-market cells is intriguing. I’m not into the “A123 losing control of their factories” theory. I do believe that these cells, as the Mavizen notice points out, are “quality control failures, intercepted during the recycling process and passed of as new”.
The sheer number of them makes sense in light of the David Anderson’s estimates (Google ‘David Anderson lithium-ion’):
– “yield adjustment” dominates all other contributors to cell-level materials cost
– yields may currently (2009) be less than 50%, given the high quality constraints mandated by the automobile industry
That’s maybe why we’re consistently seeing grey-market cell capacities of 18-19 Ah instead of the published 19.6 Ah minimum. They get thrown out because they’re out of spec – for capacity. Performance then is a different matter. As long as they can throw out 10C-23C consistently, most of us won’t mind at all.
A can of Coke says it’s 12 fl.oz. I wouldn’t mind buying it even if it actually had only 11 fl.oz. — but at 1/3 the price. As long as it tastes like Coke.
The availability of the grey market cells is indeed intriguing. But isn’t there normally a way of MARKING rejects and sub standard cells? These have full tabs, normal markings, and the serial number tag on the negative tab.
The one we built in this video did 77.75 Ah. These very nearly WERE spec of 19.6.
In any event, fi they average 18.6 at $20 and the 19.6 are $73, yes, by all means give us the rejects.
I think it is really as I said. A123 has not been taking the numbers they anticipated and the Chinese are very funny about that sort of thing. If you don’t do your part, then they think they are free to do whatever is necessary to keep the factory going.
But my source INSISTS these actually come from the USA. I don’t think he knows where they come from, or cares.
Jack Rickard
Jeff:
Glad you enjoyed it. I am NOT a mechanical engineer and indeed am famous for cross threading every bolt and nut in the place. As I’ve said SEVERAL times I’m also not a packaging guy and ANYONE could do better on this project than I can. I am an electrical engineer and actually quite good with software – when I have the time to do any of it. Which I mostly don’t.
But we have been having some overall success with our builds. The A123 thing is mostly for those seeking a less expensive battery solution to do a build. Your 911 would have been perfect. But there are many donor cars out there. Be creative. Picture what you would WANT to drive with great acceleration, in total silence, and with no gasoline, noise, or emissions.
Jack
Jack:
Sorry, I’m not aware of the properties for the potting compound you are using. I remember the soft stuff we used for sealing radar sub assembles. It appears you really are building a brick battery.
I understanding the reasoning is for mechanical stability of the connections; but, I’ m thinking that perhaps a less aggressive compound might allow you to salvage the good cells and at the same time seal the unit against humidity and loosing connections. I don’t want to second guess your decision but don’t you also need just a bit of space for the pouch to expand? Perhaps a Shore A hardness rating of about 50-80 would be a good selection. I’m fairly unknowledgeable about potting and don’t intend to alarm. Just trying to follow what an old engineering professor once taught me: ” The best engineers are those that do the best worse-case analysis .”. Google Shore A hardness for more info.
The urethane resin we are using is from Dascar Plastics http://www.dascarplastics.com/ the RP-40. It has a D-70 hardness rating as I recall.
We can tweak this design ad infinitum and probably will. I’ve already ordered some FRP 3/8 threaded rod that is a little stronger. We’re probably going to a 2x2x1/4 angle for the terminals. Probably try a little coloring in the resin next time.
Your mileage will of course vary. I like hard resin. I don’t want the cells to swell. I don’t want any movement between the cell and the cell tabs. I want it hard as a brick and virtually indestructible. I want to be able to drop it from 12 feet and watch it BOUNCE and then work. And I’ve kind of made up my mind to forfeit access to the cells in exchange for all this.
It really goes to the BMS thing. In trying SO hard to save our cells, we destroy them with all the gimmickry to save them, when in reality they are pretty hardy if left alone and replaceable for less cost than the protection. Same thing here. Yes, I can even set it up to where I can not only measure each cell, but charge/discharge/balance separately and of course recover the cells if one goes bad.
Philsophically I’m backing away from all that and going birds eye view on it. I want an automotive style and size power pack. 40volts. 75 Ah. And 75 lbs. And yes, you can run a fork lift tong into it on purpose and it isn’t going to leak anything, it isn’t going to short anything and it isn’t going to do anything. A fly in amber design. The terminals are heavy 1/4 aluminum and flat.
To get all that, I give up access to individual cells. We are treating them at the same level as individual foils in a prismatic battery. Because they are in series, this is a little soft. But I’ve been kind of doing this with batteries for awhile. We start out bottom balanced. Don’t overcharge them. And try not to over discharge them.
But sure, it’s new ground. They could get hot, gas inside and blow like a hand grenade – explosively. We’ll see.
The beauty of it is, you can use whatever resin you like on yours, and mine won’t change at all.
Jack
Further, if 100 of us each build a module, we have just re-enacted the 100 monkees on 100 typewriters scenario. One of us might write the Ghettysburg Address at random.
Jack Rickard
I assume you have not followed the results form the great monkey-typewriter experiment of 2003.
http://www.wired.com/culture/lifestyle/news/2003/05/58790
The experiment can also be used as a predictor of what happens when I devise my own pouch-cell module.
Thanks for the great work and sharing it with us all.
(love the new green-screen editing)
-Clay
Jack, as usual, love the show, but one thing stuck out at me while watching. When you were threading the battery tabs onto the threaded rod, they were deforming as they were placed so that there was a raised ring of material next to the rod. Obviously this didn’t happen with the spacers, nuts or non-conductive spacers due to their thickness. So when you tightened the nuts, those raised rings created space between the tabs where there should be complete contact. This could possibly cause excess heat because of lack of contact area. One possible fix would be to make the holes for the tabs just slightly larger than the rod instead of exactly the same size thus allowing them to slide down the rod easier minimizing the deformity, as well as allowing them to make more complete contact when tightened because the rings would simply get pressed flat again in that extra 1/32 space between the tab and the rod.
Was this an issue when you built the first block of cells as well, and is there any excess heat at higher discharge levels?
Well, the nut every so often rather smashes things a bit. But yes, larger holes would make assembly easier.
Jack
Jack:
Love your style. Just don’t want to see your name in the obits any time soon.
I check the obits each morning. So far, so good.
Jack
Jack, I agree with the merit of indestructiblity. However, to make the pack deconstructable, one could add in another parallel cell in each set if another 25% capacity is needed, at a more approachable upgrade price. Indeed, the enclosure would likely be scrapped, but I’m willing to deal with that.
Hi Jack and Brian. EVTV has certainly become my “must watch” programme! I’ve been following you since the first one and the show just gets better and better!
You were musing about the fate of the Mini E’s, 40 of them will be used here in London for the 2012 Olympics, but the rest were set for crushing, however thats a story from Green Car Reports/Wiki so I’d treat it with a bit of caution!
Strange about the A123 cells! As you have said many times, sales organisations have to “sell things” there UK based agent doesnt seem to have a lot of info about them, no prices etc, I guess they too are waiting for another non existent OEM
I spend a lot of time in Estonia, good EV scene there, the Govt did a deal to get 500 i-Miev’s from Mitsubishi as part of a carbon offset deal. So I hope to be driving one soon! They also held an EV race from Tallinn to Monte Carlo last year!
So keep up the great work, cant wait till the next one!
Regards from the UK
Mark Davis
Jack,
What are the dimensions of the packs you’ve made?
– Doc
Perhaps one idea (but I imagine a lot of work) is to match the paralleled cells so that each group has the exact same total ah. In this way you are always top and bottom balanced.
I’ve written a program to help automate the selection process (the algorithm needs improvements matches to 0.05 ah but can do better manually). Thread is here:
http://www.diyelectriccar.com/forums/showthread.php/any-excel-experts-out-therei-battery-67805.html
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I assume you have not followed the results form the great monkey-typewriter experiment of 2003.
http://www.wired.com/culture/lifestyle/news/2003/05/58790
The experiment can also be used as a predictor of what happens when I devise my own pouch-cell module.
Thanks for the great work and sharing it with us all.
(love the new green-screen editing)
-Clay
Hi Jack and Brian,
Any harmful effects to the cells from what I believe is the 350F exothermic heat given off from the RP-40 curing?
Thanks for another great show.
Mark
Mark:
The answer is possibly.
But this is ANOTHER example of a little bit of information. And like most of them, a little bit of information is normally a little bit of DISinformation.
There is no 350F exothermic heat given off from the RP-40 curing. The only 350F listed is something termed deflection heat. This is a rating measured for plastics where a certain thickness of the plastic is placed under a weighted load and it is heated until a certain amount of “deflection” or deformation is observed.
For most plastics and resins, this is between 140 and 180F. For RP40, the resin we are using, this deflection heat value is listed as 350F – quite high for such resins and plastics. This is kind of an advantage in this case as our cell won’t deform at any temperature that our cells could withstand anyway.
In ANY event there is quite a bit of exothermic heat in curing any of these quick cure urethanes and RP-40 is quite high – though nowhere near 350F – but conceivably 150F.
The first module was placed under load two days ago and failed catastrophically. There was lightening inside the bottle in this case. But it appears to be a function, once again ONE MORE TIME, of the wiring to the Cell Log 8S units. It is so hermetically sealed even that is a bit of a guess.
But it doesn’t look good. Module two, the one you saw assembled this week is now cast in resin and I’ll be putting it under load soon.
But we cannot rule out exothermic casting heat as the culprit.
Jack Rickard
Jack,
If heat turns out to be the culprit, it might be necessary to cast these in smaller parallel only (3.2V) bricks to cut down on the exothermic heat. More mass = more heat during the reaction. I could see making a simple clamp terminal in a brick about the size of a 100Ahr CALIB. I would probably keep the holes in the tabs tough as the clamping method…
One other option would be to use an aluminum mold with a double wall. Put ice water in between the inner and outer wall. One company I worked for had to do this in a fussy two part epoxy assembly they made. It increased cure time from about 10 minutes to two hours though….
Jack,
It’s a terrible shame that the first module hasn’t worked out. I hope you don’t feel too bad about it after putting a lot of work into making it.
I hope that you got the lightening in a block of ice on film. That will be fun to see. Sounds like box office gold. 🙂
I’ve generally really enjoyed this whole A123 battery design thing. I like watching the design evolve in front of me every week. It’s fascinating.
Nickkkk:
Nnnnnnnaawwww. It’s not a terrible shame at all. It’s part of the process. This is why I try to AVOID these little projects. They go on and on. ThiS IS how its done. Oh, some clever fellows undoubtedly do a better job of it. But in almost all cases you do it over and over again. The guys who gen something up, declare it beautiful and then start selling it are living in a fantasy world.
Concept, prototype, test and revise. And in some cases go back to concept and start again.
I’m of the Edison school. Not of the Tesla school.
Jack Rickard
It seems BMS can be costly:
http://green.autoblog.com/2012/01/25/neil-youngs-company-sued-for-500-000-over-lincvolt-fire/
Mr. Noto & Mr. Rickard: your work within EVTV is amazing. Selfishly sharing your findings On-line has far reaching effect, I have no doubt what so ever. It definitely springs out EV workshops around the globe.
It is hopelessly easy identifying with any of you two. I love watching your show, steadily improving before our eyes, from one to the next episode.
The way I see Edison’s and Tesla’s schools, they were product and project oriented respectively. Both of them yielding fortunes, first from small amounts and lots of sources, while the later quite the opposite.
I would like to see EVTV conceptually in between of these schools. To illustrate what I have in mind, I’ll go a bit off-topic. Slightly, because gourmet is pretty much within your field 😉
If you are familiar with chef Ferran Adrià, he deliberately closed his “El Bulli” restaurant last year, in order to open again in 2014 a Bulli Foundation. While in the restaurant it was close to impossible to find a seat, the Foundation aims to have the gained experience in service to anybody interested in cuisine.
They are to show everything online, to become a well of inspiration to chefs around the world. Your side projects could devise EVTV’s products – Edison’s approach. Currently EVTV is much more in Tesla’s school yard, devising projects. That’s why I believe it is of utter most importance to keep on with your small projects as well.
Unless your comment was on their DC / AC positioning, leaving my train of thoughts totally off-side I would like you to study it. As soon as I am in position, I will donate for all the episodes I’ve seen, and I enjoyed, retroactively, all of them.
Keep up the good and hard work, the cavalry is coming. I have some earning prospects ahead.
Best regards from Barcelona, Spain
Edison approached invention as a process of discovery and refinement marked mostly by experimentation and improving process redundantly.
Tesla was reported to have invented the AC polyphase motor entirely as a thought experiment with the first prototype working perfectly.
Actually, I’ve never believed the Tesla version and trace it to Tesla himself misrepresenting the process.
Jack
I enjoy every episode, and agree the green screens and close-ups add polish. Hope to be able to hit you with a bit cash soon, though I will doggedly stick with youtube viewing of the show. How about cutting a long socket wrench in half and tacking each half inside a 12″ tube [or tacking socket inside two right angle metal strips of length] so that the tedious threading of the nylon rods could be accomplished with the battery powered driver? On the catastrophic battery failure, does the high viscosity resin produce/exude water while curing? All of the components of the battery pack look hydrophobic, so it seems the water vapor would tend to condense in the connection area between the batteries–and lend to shorts? Have you conducted any forensic study of the zorched battery pack? I thought of a simple test which might help. Put a drop/dollop of the un-reacted resin components on a piece of paper as well as a drop of the combined components and observe for water migration. If the ultra viscous materials do not display seepage, create a piece of hardened resin leaving a test well/cavity. Wrap a teaspoon of household sugar in paper and give it the ‘insect in amber’ treatment. Wait a day or two and determine if the sugar suffered (water) infiltration. I found an very interesting five page history of electric vehicles I want to share: http://www.electricvehiclesnews.com/History/historyearly.htm
It’s difficult not to consider some variant of what’s old is new again, even down to battery swapping stations. I was struck with the notion that the inverse/inflection of lower end user gas pricing which established ICE dominance back when is now set to re-crown EVs. Please also consider Anthony Bourdain on scootering in Rome: http://www.youtube.com/watch?feature=player_embedded&v=aH4u1Tbd8XY Of course this would be all the better with an e-scooter as in this shining example on the streets of Barcelona: http://www.youtube.com/watch?v=3y9rgwCAdJQ&feature=autoplay&list=UL3y9rgwCAdJQ&lf=mfu_in_order&playnext=1
Finally, http://www.greentechmedia.com/articles/read/electronvault-a-new-way-to-build-batteries
“…ElectronVault’s business model will, ideally, give end-users more bargaining power in the storage business. The company plans on licensing its know-how to car companies and others. Thus, instead of having to buy completed battery packs from manufacturers, they will be able to buy cells and, with ElectronVault’s know-how, weave a battery pack together themselves. As an added bonus, these battery packs will be able to mix and match cells from different manufacturers, ameliorating spot shortages…Prior to ElectronVault, Ferber was a science director at Tesla, where he worked on batteries…”
I’ve whipped up another video with some more conceptual musings on building A123 Pouch Cell Modules. These ideas are mostly intended for people wanting to be able to pull their Modules apart again. It’s not really a “how to” – it’s just some general ideas that I think can be improved upon. It also relies on the module concept working reliably in the first place.
Excuse the terrible audio quality. To save your ears, feel free to mute the sound and read the subtitles instead.
For anyone interested, heretiz: Module Concept Video
This leads me back to the thought of tightly clamping the cells, like the plates and straps that used to ship with Thunder Sky cells. I would add a plastic sheet between the end plates and the cells and between each 3.2 volt block. These cells may prove to have external leakage like Victor’s first experiment with pouch cells.
If these end plates extended up, so that the terminal blocks could be connected to them in a non-conductive fashion, you would have a rigid block that would limit tab stress.
If the cell tabs are Aluminum I would also switch to an electrical grade aluminum for the cell connectors, like 6101. 6061 aluminum has about 70% of the conductivity of 6101. Of course, this isn’t an issue at low currents.
I use to work with a fellow who believed in the number three. To rinse out a container, you’ll have it 99% clean by the third rinse. If you make something, it won’t be until your third iteration that you’ve worked out most of the problems and so on. Working as a electromechanical tech, doing product failure analysis, working in product development and R&D for many years I found that to be pretty much true. (Getting the CEO, marketing and project engineers to buy into that concept… I have yet to see a timeline that was worth the time that went into creating it.)
Good work! Hopefully you’ll have your A123 packaging worked out soon.
Klaus, I tend to use Pi for estimating time, cost and attempts to bring and idea to realilty from an educated guess.
Your fearlessness reminds me of when I was 20, Jack. You and Brian are great examples to us all. Keep blowin’ stuff up so we don’t have to!
Evfun:
Using the plastic sheets and then binding the module together would give it some much needed rigidity. A simpler scheme for installing the modules in the battery box could be dreamed up too if the plastic sheets supported straps running the length of the battery box.
– – – – – – – –
I forgot to mention in the video that a heat resistant paint such as those used on stoves and furnaces could be used to coat the exposed edges of the aluminium spacers and the battery terminals. It should protect the metal that is exposed to air somewhat.
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Jack, Love the show and love that you are looking at the A123 cells. I am one of those guys that loves getting there hands dirty and also would like to make a difference. I want to convert a car but the founding is limited know but I am working on that. The A123 cells will make a difference for me with the power I want in a smaller pack. I drive 22mile a day to work and back and with a 100ah pack of Thundersky’s that’s two charges a week and a possible 28 year life. A 40 or 60ah pack of A123’s will give me the punch and the price that will get me into a EV sooner then later. I have two questions for you. First do you think these cells may swell with time. Secondly, I am having trouble finding the dimensions of the tabs. I have the case dimensions but I am hoping you can give me the tab width, Height and distance between the tabs. I am trying to work out a pack design of my own and these dimensions would help.
Jack, Love the show and love that you are looking at the A123 cells. I am one of those guys that loves getting there hands dirty and also would like to make a difference. I want to convert a car but the founding is limited know but I am working on that. The A123 cells will make a difference for me with the power I want in a smaller pack. I drive 22mile a day to work and back and with a 100ah pack of Thundersky’s that’s two charges a week and a possible 28 year life. A 40 or 60ah pack of A123’s will give me the punch and the price that will get me into a EV sooner then later. I have two questions for you. First do you think these cells may swell with time. Secondly, I am having trouble finding the dimensions of the tabs. I have the case dimensions but I am hoping you can give me the tab width, Height and distance between the tabs. I am trying to work out a pack design of my own and these dimensions would help.
Jack, Love the show and love that you are looking at the A123 cells. I am one of those guys that loves getting there hands dirty and also would like to make a difference. Limited found has me in planning mode which is not a bad thing it gives me the time to research and make the right choices. The A123 cells will make a difference for me with the power I want in a smaller pack. I drive 22mile a day to work and back and with a 100ah pack of Thundersky’s that’s two charges a week and a possible 28 year life. A 40 or 60ah pack of A123’s will give me the punch and the price that will get me into a EV sooner then later. I have two questions for you. First do you think these cells may swell with time. Secondly, I am having trouble finding the dimensions of the tabs. I have the case dimensions but I am hoping you can give me the tab width, Height and distance between the tabs. I am trying to work out a pack design of my own and these dimensions would help. Thanks.
Ok. I get it. Others want to play. Excellent. I gather that after about SIX SHOWS you guys rate waking up to the meager but very real advantage posed by these cells. They will scratch the lead acid itch. Yes, you can build a car for less with a lesser range this way. IF the cells remain available and the price really needs to come down a bit.
But yes, we have to find ways to live with them. I suspect, since they are LiFePo4, we can use the same bottom balance and undercharging techniques we’ve been using and AGAIN throw the whole BMS thing under the bus and survive just fine – saving a huge investment and expense.
I think the thermal issues could be more of a challenge than our prismatics, but not insurmountable.
The big if is whether they will remain available and if the price will fall just a WEE bit further. At the point where you can actually receive these cells in your driveway at about $19 each – they become THE option for many of you.
I did do a dimensional drawing however crude.
A123 M20HD-A
Peter McWade begged eight cells and offered $35 each plus shipping for eight of them. I don’t really intend to be in the battery business, but mailto://jack@evtv.me with your address and quantity desired and we’ll shoot you a Paypal Invoice. If you pay it, I guess I’m out that number of cells.
Jack
I continue to enjoy every episode, and agree the green screens and close-ups add polish. Hope to be able to hit you with a bit cash soon, though I will doggedly stick with youtube viewing of the show. How about cutting a long socket wrench in half and tacking each half inside a 12″ tube [or tacking socket inside two right angle metal strips of length] so that the tedious threading of the nylon rods could be accomplished with the battery powered driver? On the catastrophic battery failure, does the high viscosity resin produce/exude water while curing? All of the components of the battery pack look hydrophobic, so it seems the water vapor would tend to condense in the connection area between the batteries–and lend to shorts? Have you conducted any forensic study of the zorched battery pack? I thought of a simple test which might help. Put a drop/dollop of the unreacted resin components on a piece of paper as well as a drop of the combined components and observe for water migration. If the ultra viscous materials do not display seepage, create a piece of hardened resin leaving a test well/cavity. Wrap a teaspoon of household sugar in paper and give it the ‘insect in amber’ treatment. Wait a day or two and determine if the sugar suffered (water) infiltration by inspecting for granularity. I found a very interesting five page history of electric vehicles: www(DOT)electricvehiclesnews(DOT)com/History/historyearly.htm
It’s difficult not to consider some variant of ‘what’s old is new again’, even down to battery swapping stations. I was struck with the notion that the inverse of lower end user gas pricing which established ICE dominance back when is now set to re-crown EVs.
Finally, www(DOT)greentechmedia(DOT)com/articles/read/electronvault-a-new-way-to-build-batteries
“…ElectronVault’s business model will, ideally, give end-users more bargaining power in the storage business. The company plans on licensing its know-how to car companies and others. Thus, instead of having to buy completed battery packs from manufacturers, they will be able to buy cells and, with ElectronVault’s know-how, weave a battery pack together themselves. As an added bonus, these battery packs will be able to mix and match cells from different manufacturers, ameliorating spot shortages…Prior to ElectronVault, Ferber was a science director at Tesla, where he worked on batteries…”
Mic,
Good work on your new design and animation. what I thought when watching it though was that the design relies on the plastic nuts staying in place whilst the car is bouncing down the road. One of the reasons for casting the cells was to lock the nuts in place so they couldn’t move. I don’t know how big an issue this would be. I’m sure there is some way round the problem, if indeed it is a problem.
———————-
I had this idea a while back of another way to clamp aluminium blocks together. I thought I would mention it in case anyone thought it was an idea that would work and that they wanted to take up. It involves these things called “3 prong T-nuts”. I have to confess that I have no experience using them, but I found them the other day and they looked like something that might be useful.
Here is a picture of one screwed on to a bolt.
http://www.flickr.com/photos/urbanbicyclist/5302521333/
Here is Mcmaster-Carr’s Tee Nut webpage:
http://www.mcmaster.com/#tee-nuts/=fznyto
What you would do is drill a hole in an aluminium block for the main part of the nut and then have 3 small holes surrounding it. You would then drive the nut into the holes so it couldn’t move. The prongs would stop any rotation and the screw would stop it moving in and out. You would then get a second block of aluminium and drill a hole for a screw in it. To clamp the blocks simply thread the screw through the hole in the second block and screw it into the T-nut in the 1st block. Locking washers could be incorporated to keep the thing from coming undone.
You could use this system to avoid having to do any casting of nutserts. I’m thinking it might be useful for people who are planning to make single batteries mimicking the Thundersky/Calb ones. I was also thinking that you could combine it with Mic’s design. If you use a hex head bolt then you could tighten the clamps with a wrench and I think that would make construction easier. The plastic rods would stay in the design, but they would primarily be used to hold the insulating plastic blocks in place. Each tab would have 2 holes. An inner one for a plastic rod and a central one for a metal screw.
If I can summon the energy later I may make an diagram.
Jack,
I received the battery strap order yesterday. As I would report on Ebay,
” Great Merchandise! Fast Ship!! Thank You!!! A++++++++++++++++”
Regards,
Larry
Larry:
We strive for that five star rating. Glad you received them in good order.
Jack Rickard
Instead of casting the module in urethane, what about sandwiching the completed module between endplates of aluminum, plastic, or composite sheets? The best thing would probably be aluminum sheet with angle reinforcement the same distance as the threaded rod for the terminals. The angle would add strength and clamping force to keep everything ridged. The endplate material would spread out the force over the entire cell. When combined with two threaded rods at each end of the module you would effectively sandwich the entire pack between the endplate material with 6 bolts holding it together, 2 at each end of the module and the threaded rod of the terminal. Passing the terminal threaded rod through the endplates and using them apply pressure to the endplates would also stop any flex or stress on the terminal. This would be similar to Mic’s video but the pressure would be at the module level instead of the box. This design, if you used aluminum for the endplates it would also probably be lighter, have better heat dispersion, and allow access to individual cells in case of a failure.
Just another idea.
All possibilitiies. One thing is sure, the urethane model isn’t’ working. Blew module two wide open today, under pressure, venting gasses, etc. No big event electrically. Took 75 Ah out. Put 75 in. It was a mess.
I’ve blown two of Mics modules sky high now. At 48 cells a pop. This is no longer fun. We need another idea….
Jack Rickard
Jack,
Sounds like they need room to expand and release the heat. Well I guess I will have to change up my idea a bit. So I will go back to my original idea.
Do we get to see the results of the mess?
Pete 🙂
I wonder if resin is seeping between the tabs and blocks. Might be better to just spray foam them into a box.
Jack,
As a suggestion could you build another Mic module but instead of casting it in resin cut two pieces of fairly thick polycarbonate and use them at either end with threaded rod to clamp the cells. At least then you could see what is causing the issue. Be it the terminals , the casting resin etc. I’ll be doing this myself in a week or so. Got 100 cells on the way.
Damien Maguire.
Jack. Do we get to see that?
Padraic
Jack. Do we get to see that?
Padraic
How about flooding with sulfur hexafluoride gas after curing, or better, bowing to Occam and da Vinci and containing the battery pack in a breathing, Cylon-worthy plexiglass design as seen in one of the shared videos?
Back to reverse dovetail clamps. Made out of a cast aloominium? Six tabs = 28mm wide bottom width of dovetail (for 3 per side). Twin gang for adding cells in series. Double width for stacking cells side by side or simply a provision for bolting/locking together. The screws for drawing them up will be at the front for easy servicing.
Maybe those burrs after drilling your tabs are a very bad thing when it comes to contact area?
Hole punches are not a bad price:
http://www.amazon.com/Heavy-Duty-12-Piece-Hollow-Leather-Plastic/dp/B000KE17JO/ref=sr_1_3?ie=UTF8&qid=1327853591&sr=8-3
Sorry to hear that Jack. That’s a lot of work as well as a lot of money down the pan.
How about taking a look at the HP Headways? Maybe a string of 10 in a square cross section acrylic tube with simple double-ended setscrew between each pair – plus a lengeth of lhdc of course…
John:
I have some here and we will do a piece on them but they just never do quite bubble to the top of the priority pole. They are NOT a solution for cars. Sorry.
Part of it is just price. The latest ones are 9 Ah I think for $27 plus shipping. This is just nonsense. There is no $3 per Ah solution. It doesn’t really matter what the characteristics are at that price.
Jack
Jack,
perhaps you should “investigate” a little bit about the Kokam modules. They are the same “style” pouch cells. And they do work in strings.
Jack,
Perhaps you should “investigate” a bit about the Kokam cells. As you know, they are the same style pouch cells, and they are working in strings.
However, they have a quite well manufactured Al casing.
Jack,
To quote John Wayland who owns the “White Zombie”
“…we blow things up, so you don’t have to.”
Although, You blew up your second pack and it is
“no longer fun” I applaud you on your effort to “go where no other man has been before.”
Mark Yormark
Jack,
To quote John Wayland of Plasma Boys Racing and White Zombie fame.
“…we blow things up, so you don’t have to.”
Although the blowing up of the second pack I am sure is discouraging. I applaud you on your effort to “go where no other man has been before”
Mark Yormark
Now that is circular, and I’ve heard everything. John Wayland, quoting Jack Rickard, without attribution of course, and qauoted back WITH attribution to Jack Rickard’s blog. Great. This Internet is just the tits.
I thought that John started using that statement when he dropped a wrench when wiring up an AGM pack in White Zombie. If so, wasn’t that before you said it or is my time line all messed up?
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The phrase, “We blow things up, so you don’t have to!” has been attributed to John Wayland for well over a decade. It is mentioned in the March 1999 issue of Wired magazine, on page 4 of the feature “Suck Amps!”
http://www.wired.com/wired/archive/7.03/
Jack,
Any evidence of arcing at the connections? Probably difficult to tell buried in urethane. Were you nearby and notice how hot the assembly was? I might suggest clamping the assembly between some plywood block with all thread tie rods and not worry about the casting scenario. You would be able to observe what’s happening easier.
Jack, Thanks for the more explicit dimensions! It turns out my models were all off… I had assumed the dimensions I found elsewhere included the tabs.
Your service to the community is invaluable!
Hi Jack,
I had a nice long reply typed out the day after the show and it went away as I tried to post it.
I tried to comment about how easy it is to make a high resistance connection with the cell tabs of these cells. I’ve been playing with them for a few months now and a few times the folded over bit left over from drilling creates a small area with two layers of tab material instead of a nice clean single layer. In my case it created such a hot connection that I melted my plastic insulator and burnt my hand before I realized what was going on. During disassembly I found a single poor connection that didn’t clamp properly. I have since moved to a hole punch instead of a drill with much better results.
At the currents these cells can dish out, any imperfection in your assembly technique and implementation can cause some insane heat very quickly.
I wouldn’t rule out the assembly method or even the urethane without further testing, even if it’s just making a single 75ah cell as a proof of concept.
I’m building serviceable 4S3P modules using the old aluminium block method with good results even if it is rather time consuming.
Good luck with the next design, I hope you have some of the fireworks on tape.
Robin
I might have missed it, but did you do anything to remove the aluminum oxide from the spacer blocks before assembly? That, in addition to the burrs from drilling holes, might be something to look at.
Christopher Fischer shared this video
www(DOT)youtube(DOT)com/watch?v=_wZ34syIEMU&feature=related
of the Cylon-worthy Rimac battery module in EVTV’s first post of 2012. Am I missing a fatal flaw which precludes it from consideration in Cape?
Quite easy to be a general after the battle. It is of utter importance to detect what could went wrong with two destroyed packs. Has the cause been the same?
Casting the cells in the urethane in order to protect the pouches, immobilize the tabs and protect the contacts, in a battery pack mounted on the vehicle might still be a good idea.
I suppose it turned out to be a dead end simply because it entered the equation to soon in your A123 introduction play. I see couple of viable scenarios for developing further A123 pouches to battery assembly proposals:
1) a “classic” approach of a battery box, rather isodiametrical – boxy. or 2) to go for a “pizza box” solutions
Eventually, in any of these cases, a resin non-sticking mold plastic sheets could be used for a surrounding enclosure, to be sealed in resin all together.
Making it a “fly-in-amber” indestructible, I would leave for the last developing step, as an desirable, yet an additional value feature.
A bit off-topic: do you consider this OEM advertisement a game changer or at least a tune setter? I find it quite ground breaking.
The indestructibility of the fly in amber didn’t quite work out as the second prototype split wide open in two places.
The cells swelled and burst the block, vented electrolyte, everything.
What caused it? I took it down quite low, recall all the cells in Module 2 were bottom balanced. And then charged it immediately. Discharge and Charge were at 40 amps, about 0.5C. It was not at shutoff voltage when it blew. I think one set of cells shorted, and the charger had put about 80Ah into a 75 Ah pack as a result..
Interesting test. Doesn’t augur well for a sealed 40volt module which I was wanting.
Thsee modules have 48 cells in them. I don’t know how many I can build before I have to declaree this a loser. I liked the concept, but so far it isn’t working out.
Jack Rickard
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Dan:
You PROMISED if I turned the moderation back off for the others that you wouldn’t post. Now what’s this???
Jack Rickard
it’s a bit ironic you should ask me to respond here..
I suggested it but you never replied. I posted a comment just for you since I expected the moderation was still in effect but when I could see there was no moderation I graciously deleted my comment. but of course you didn’t appreciate even that.
feel free to delete this comment.
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Did I just get rickrolled into watching a state of dumbama address?