Tesla continues to awe and amaze the aborigines. Elon announced Friday that he was reversing position and backing away from his plan to take Tesla private. I for one am quite relieved. I have publicly stated that Tesla has some enormous blue sky opportunities ahead and have predicted a stock price of $1500 by February of 2023. The concept of privatization really meant to me that I would no longer be able to participate in the party.
Musk’s reasoning for the reversal was entirely logical and I find no disingenuous aspects to it. And it was pretty much what I had predicted. He had promised that existing shareholders would be able to retain their shares into the private zone and found out that this was just not something he could technically accomplish. I had feared he would waffle and revise.
But the second very real issue was the existing large block shareholders. Many of these have their OWN investors and charters and prospectuses which kind of outline what percentage of their holdings can be in private startup ventures that are illiquid. On consulting with them, he found they would not only vote against privatization, but would have to liquidate THEIR holdings in Tesla if he prevailed – no choice in the matter.
I found it VERY interesting that the “committee” received a proposal from Silverlake Investments, who are experts at bitcoin robot trading, that included up to $30 billion in funding to go private with the largest investor in the package – VOLKSWAGEN. See my previous blog about Tesla now being “in play” and likely suitors. It was still shocking to see this play out so quickly. I’m unaccustomed to making predictions on Mondays that are old news by Friday. The pace of developments here is just shocking.
So here it is Monday morning, with another stomach churning lurch downward in Tesla’s stock price, and for me, another buying opportunity.
The parallels continue. The alt-left libtards insist I am part of the Trump “base” blinded to his sins and the shorts would have you believe we are likewise Tesla fanboyz who simply cannot see reality. I find both positions interesting, but just not very.
In both cases clearly I see things they don’t. That’s not blinded to my way of thinking. Feels more like being the one-eyed king in the land of the blind.
The underlying forces that affect Tesla appear quite positive and increasingly so. Their production of the Model 3 is persuasive to me. I find the Bloomberg Model 3 Production Tracker quite conservative in that they are working mostly from VIN numbers of REGISTERED Model3s, not production numbers but cars hitting the road. As they have to be paid for and delivered before they can be inspected and registered, that count starts to look irrefutable and rather unfudgeable.
Tesla claims their labor hours in producing the Model 3 have dropped 30% from peak and so the cash flow at 5000 units per week is impressive. More so at 6000 and rumor has it that the actual factory production is getting very close to that. My rather basic Model 3 came in at about $56,000 and that went directly to Tesla – no intervening dealers of course. And so at 6000 units that looks like/sounds like $336 MILLION dollars per week coming in the door via the web site. I’m guessing with all wheel drive and performance models coming online, more like $350 million. Good work if you can get it.
I actually do NOT believe all 455,000 of the original reservation holders are actually going to buy a Model 3. The reservations were for a $35,000 Tesla Model 3. And I was clear in predicting there IS no $35,000 Tesla Model 3 and you would never see a $35,000 Model 3. The only existing $35,000 Model 3 is parked right next to the $55,000 Model S. And there the two cars sit firmly lit in Elon Musks imagination. They were always price targets for his design team. Not sticker prices for you and I.
Further, we have not escaped the “low hanging fruit” paradox that has plagued EV manufacturers from the advent of the first sale. For any EV, at any price, and at any specification, there is a latent demand from a small band of Jack Rickard types that are going to buy it regardless. Indeed they are waiting for you to finish the design and get it made- and somewhat impatiently.
But after you have filled that latent demand or picked the “low hanging fruit”, selling the same car into a wider audience of just general car shoppers is a much more difficult sales/value case to make.
And so Tesla is having no difficulty meeting “demand” for the Model S and Model X as the low hanging fruit for those cars and at that price point has pretty much been picked. New buyers are almost entirely friends and neighbors of the existing apostleship and not only is this “word of mouth” advertising the most effective, but Musk correctly assesses that it is the only kind that will work at all hence his reluctance to purchase an ad on say EVTV, to promote the car. I’ve already sold all we can just by talking about it.
All of that said, and assuming Tesla can achieve 10,000 Model 3 units per week late this year or early next, it will be a couple of years before they can work off the backlog and competently deliver a car to a buyer within a month. And anyway you count it, thats a million cars later.
Further, the vaguely blue sky is hardening to a delightful cobalt blue. Talk of the Tesla Pickup Truck has turned ugly and Musk is now chiding his design team to develop it parallel with the Model Y.
The Model Y is of course the crossover Sport Utility Vehicle (SUV) version of the Model 3 – basically a rebodied car using the same chassis and drive train but with a different final assembly body work. There is no doubt that SUV’s outsell sedans by a signficant margin in the U.S. today. And Tesla nees one. The overly ambitious Model X just wound up being too expensive for almost anyone.
But the number one selling personal transportation device worldwide has been the pickup truck for nearly a half century and the Ford F150 sales have never been challenged for about 37 years now. GM can produce all the TV commercials their budget will allow showing smiling yucks prefering the Silverado to that “other” truck. What they can’t do is tick a notch in the sales numbers.
I don’t think Tesla can either. But they could certainly sell a lot of Tesla pickup trucks while failing.
More bluesky reality popped up again last Friday with the surprise announcement that the Tesla Semi had driven cross country to Annheuser Busch in St. Louis and JB Hunt in Arkansas entirely autonomously. JB Hunt is one of the largest over the road trucking companies in the world and I was in the Navy with one of the sons. The company claims it didn’t even have a chase car on it which I find very nearly preposterous. They did have teams on site and ready at Supercharger stops to hook up as many as four Superchargers to the trucks simultaneously. But they were driving across country unaided in any event.
There are a couple of interesting aspects to this. First is Tesla’s own little logistics problem shuttling quite heavy battery and drive unit equipment between the Gigafactory in Sparks Nevada and their assembly site at the Freemont California factory.
This is no small expense. But if you charge it on solar, and don’t need a driver, it becomes somewhat less expensive operationally. And they have a good test track for autonomous electric Semi trucks and trailers. They can tweek shapes and hardware ad infinitum and get a pretty good take on efficiency improvements in range and speed and of course check autopilots on various weather variables.
As you know, I’ve been an autonomous driving skeptic – I still can’t get either homelink or summon to work reliably and indeed I would characterize it more like “comically”. It is SO baaaaaad.
And I further predicted legal difficulties over the basic concept. It’s already happening too. A man was arrested for driving under the influence this week after crashing his Model S into a firetruck. Yes, this was the second instance of a Tesla trying to mate with a firetruck on a public road. But this guy’s story of course was that it was in autopilot – he thinks.
But the over the road truck market is just pregnant for this. Talk about low hanging fruit. First lets address all the poor truck drivers about to lose their jobs. Some news. There are now over 60,000 unfilled positions for truck drivers – can’t hire em at any price.
And you can make a VERY good living as a truck driver. If you are not habitually drunk and can see out of one eye, you start at about $50k per year and if you aren’t also brain dead you can do $100k per year within a year or so.
So why isn’t EVERYONE a truck driver? Well it’s a hard life. It’s an easy job to begin with. But living on the road day and night for weeks months or years at a time just isn’t a life.
A friend of mine had two wayward sons who discovered this in short order. They stumbled on truck driving to make money and it went SO well they quit their truck driving job and invested in their own brand new shiny tractor and tried their hand. That went well enough they bought a SECOND and then a THIRD.
They were just raking it in but had a very difficult time hiring a third driver that wasn’t just a horror. And so they scaled back to two trucks and the two of them. Again, they were making it work big time.
Two years later their trucks are for sale and they’ve taken jobs doing a milk run between Cape Girardeau and St. Louis that has them home for dinner every evening.
About two years of hard truck driving drives home the lesson that money isn’t everything. Very few can stick with it. It’s a hard life and rather a mean life as well.
So I’m guessing not many tears even from truck drivers themselves. The trucking industry just wouldn’t be able to contain themselves if someone can come up with a driverless over the road rig. Indeed, if he could just pull off the over the road train he described – a driver in the head truck and four following behind him autonomously, there IS no price they would NOT pay for this. And frankly, they wouldn’t care if it was powered by Kingsford bag charcoal. Virtue signaling is not what trucking companies are about.
But the deep cranial damage caused by dealing with truck drivers is. They suffer deep and ongoing pain over this and anyone with an aspirin will do.
So going forward, I find Tesla at this mornings $308 share a license to steal money and it cannot be legal for long. I keep looking over my shoulder fearful Mueller is going to show up wanting to squeeze me for any information I have on Trump maybe overfilling a bicycle tire in direct violation of federal safety standards, and willing to send me to jail for the rest of my life over Tesla CALL trading to get it.
The parallels between the press coverage of Trump and the press coverage of Musk continue to build. I think purported “journalists” are actually starting to ape each others behavior in this area. I guess once prostitution becomes socially acceptable it is just ok. But it brings just a little taste of vomit to the back of the throat to watch the whoring going on in a career field rather close to my wheelhouse as a publisher. Yet another head of Tesla’s Public Relations/Corporate Communications has moved on. Now THERE’s a job you want to apply for.
More brightly, our testing of the PowerSafe 100 continues with ongoing mysteries and anomalies sufficient to keep me entranced for days and weeks ongoing. I just have never had it so good. So many strange results and surprises. We put 2500 amp hours IN to the battery this week and promptly took 1588 out and found the limit both times. ?????? This makes no sense. The device magically kicked off the Solar Edge grid tied inverters without interrupting power production at all and promptly five minutes later they all came back up and no one can explain why or more importantly how. Potentially very useful information.
I think it is notable that our investigations into AC coupled charging of solar energy storage batteries has not gone unnoticed
U.S. manufacturer ENPHASE (stock symbol ENPH at $4.73) really invented the microinverter in 2011. It has quickly gained a 27% share of all residential rooftop solar and they have JUST completed their acquisition of SunPower’s inverter business. They will now be sole supplier to SunPower. Recall they make the 22% efficient cells with no electrodes on the front, all back cell connections. I love em buy you can’t actually buy the panels. I get them from China on our flexible panels.
Enphase is quietly rolling out to investors their IQ8 ENSEMBLE concept which will not be available until sometime next year. But it more or less duplicates our on grid/off grid concept specifically with AC coupling to a device that then charges the batteries in a solar energy storage capacity.
One of the reasons ENPH is rather suppressed as a stock play is the Chinese manufacturer HOYMILES. Still very preliminary but they are talking about the same concept – AC coupling their microinverters to batteries.
Of course in both cases they are talking about smallish batteries at eggregious prices. We just don’t think that dog will hunt. But repurposing inexpensive salvaged EV batteries will.
And so we seek to enable YOU to add a largish battery inexpensively (relatively speaking) to an existing AC coupled grid-tied system using any or all of that basically by plugging it in to the loads panel.
And our PowerSafe100 is a Tesla PowerPack2 sized version of that.
In this episode I discuss our new display efforts and ongoing developments with the Raspberry Pi display and ESP32 based Tesla Model S battery module controller.
Collin and I have been collaborating very productively and I might say enjoyably on the software for both the ESP32 controller and the Raspberry Pi display and are enjoying very pleasant and daily progress.
But I do describe in this video the reason for my reluctance to deal with 48v systems in a discussion of I Squared R losses and how devilish they are to deal with. Fans and liquid cooling schemes are just not very effective when your heat problem is in a conductor itself.
Ultimately this is headed for a crying need for a new Inverter design where we can use large strings of 16 individual modules for our 345 volts, but do 20kw and have control of the software and frequency and so forth of the output. I don’t really see anyway around it. We need to do our own inverter. Tesla already has a bidirectional 50kW inverter for their Powerpaks and I guess I need one too.
What is the charge cut off voltage per cell of the Tesla module?
It is quite configurable. Right now I think I have CUTOFF set to 4.15 volts and RESUME set to 3.90v
Jack I’m now officially passing gas. I received my Model 3 black in color last Wednesday. I chose the dual motor model at the last minute just for fun. I have also already consider taking it apart. On another note I was told today Raspberry Pie announced a PoE model thought you would like to know.
PoE is interesting, and the price is pretty good ($20 for a PoE hat?!). But, we’re not doing a thing with ethernet at this point and I don’t see it being something on the radar but I suppose you never know. One thing I’d wonder, though, is how many people really have PoE enabled routers? The average person is going to have the cable company’s router or the phone company’s router and they’re all consumer grade garbage with no support for much of anything. I doubt that any of them are PoE enabled. So, the utility seems a bit limited without additional hardware on the router side too. But, it might help in instances where the rPi is installed somewhere where there is no power. I think that’s unlikely as it is most likely to be used where people are and people tend to like to be surrounded by outlets.
Be careful about the official Raspberry Pi PoE hat. It has a design flaw and won’t reliably give you the power you need if you run anything with the USB ports. I recommend waiting for v2.
Hi Jack,
You said,”More bluesky reality popped up again last Friday with the surprise announcement that the Tesla Semi had driven cross country to Annheuser Busch in St. Louis and JB Hunt in Arkansas entirely autonomously.”
I read it as alone, i.e. with no escort, not autonomously>>https://www.engadget.com/2018/08/26/tesla-semi-truck-travels-cross-country-alone/
snip from above link
In response to an Electrek piece on the Semi’s latest visit (to Arkansas trucking behemoth J.B. Hunt), the CEO noted that the Semi has been traveling thousands of miles entirely by itself, using the existing Supercharger network. The only necessary help is an “extension cord” to help the truck plug in. To be exact, it’s a system of cords that plugs into multiple stations at once to top up the Semi’s giant battery before the company’s Megachargers come online.
That solo travel is likely meant in part to reassure customers (including J.B. Hunt) that the Semi is already capable of handling long-distance trips without escort.
Of coarse, I could just be typing myself smart.
Keep up the great work!
Karl
I’ve known about I squared R issues but it never occurred to me what implications that will have in an off-grid solar application…especially at 48V. You’ve swung my vote toward a 360V battery pack once I get off grid. I ordered a 6kW grid-tied system and should take delivery of it tomorrow. It’ll be interesting to see how much power this system will make through the winter.
The implications were a little minimal with a 5kw system. But we’re not about Tiny House Nation or the whacky living off the grid guys. We want to power a shop that charges cars. Or at least a hacienda in Costa Rica. And I don’t advocate suffering for the privilege. I want plenty of juice for my Smartphone and GoPro.
Jack, don’t you have an electric engineer around you? Your I Squared R “problem” is simply not devilish. Science gave us tools about 100-200 years ago how to manage it. We know exactly how and what to manage it. I think the issue is – and I see it in your comment referring the quality of your conductors and your other comments and your designs – that you are mixing resistivity with Resistance, not considering Pouillet’s law for design of your conductors and your bus bars, and missing the Bloch–Grüneisen formula of the thermal dependence of resistivity and such resistance through Pouillet’s law. Your problem can be solved with two 30lb copper bricks rated 2500-3000A for each terminal and bit different wiring (especially for safety reason). You are so close to do it right but this thing this way can explode to your face. I am honestly worry about that. I cannot tell you all the potential problem why you are taking less Amp out from your battery because your bus bar are not uniform, per Pouillet’s law , and you can easily loose that amount of energy as a loss all over the place. I will write an e-mail to you to explain. Can you just not use this setup, Powersafe 100, for one day until you read my mail tomorrow? Please.
Don’t I have an electric engineer around me? What kind of assclown comment is THAT? But in response to your request, NO I cannot just not use this setup until I am graced with the bounteous blessings of your next missive. We’ll be running it every day as we have for the last couple of weeks to power the shop.
Yes, no doubt I’m confusing resistivity and resistance. And Bloch-Gruneisen, infamous though they are, probably can’t help me. But it’s nice to know that at least someone out there, i.e. you, holds the keys to dismissing the laws of physics and I squared R losses. I had feared I would just have to learn to live with them.
Electric heat loss is I squared R. No disagreement there
R is defined by Pouillet’s law as rho*l(ength)/A(rea), where the rho is the resistivity of the material, length of the material and cross-section of the current of the material.
So, the electric heat loss can be defined as I squared rho*L/A.
We can clearly see from the equation that the shape of the buss bar and conductors are important. The same weight of copper can and will have different resistance based on the shape of it. And we can see from the equation that lengthy conductors are increasing the thermal loss and big area cross sections materials decreasing it.
One more twist is that rho is thermal dependent. At higher temperature the rho increases.
So, if we have significant heat loss (because of I squared R) what cannot be dissipated in this case the heat loss will further increase because rho increases. And can create thermal run-away. And significant loss of usable power which might account some of your losses you write about in your blog.
Perhaps you meant well but… that wasn’t quite the way to explain your position. For one, yes, nearly no one knows (much less cares) the difference between resistivity (essentially the property of a material that specifies how much it wants to allow electricity to flow) and resistance (that property over a given cross section and length to yield the actual resistance to electrical flow – ohms). That is, resistance is the total amount that a given chunk of material will limit amperage for a given voltage. Resistivity is the property of the material that governs the total resistance given cross section and length. You could have easily explained the difference like I just did. Instead you came off more like “I can’t believe how stupid you are, you don’t even know X, Y, and Z” without even attempting to explain what X, Y, and Z even are. Further referencing this trend, you actually went to the extreme of using “Bloch–Grüneisen formula” which, while real and valid, is still a rather obscure way to talk about what you really mean – the fact that materials change resistivity/resistance based on temperature. It’s much better when explaining things not to go right to the $100 words and instead use plain English. Nobody gives a crap what the equation is called and it would have been far better to just explain the actual concept not the obscure name the formula has. Nobody gives a crap who Bloch or Grüneisen are nor should the average person. The more important part is the “concept” being applied here – that a given chunk of copper will increase in resistance as the temperature increases. This can lead somewhat to a thermal run away situation where the increased heat causes more resistance which then causes even more heat, etc. Of course, it is self limiting usually as incandescent light bulbs can prove (as well as the very common PTC fuses used all over the place). But, often the self limiting point is a bit warmer than people would like to get to.
To recap, you aren’t wrong about the general concepts but you went about it all wrong. Use English, the Queen will thank you. Explain what you mean rather than just making yourself look smart by using the most complex and obscure terminology you can. I’ve been around a while and I still had no idea that Pouillet’s law was the name for (resistivity * cross section * length) It would just plain have been simpler to explain it. It really all reads like you wanted to make yourself seem like the God of electrical engineering. That’s just plain off-putting and you got the appropriate response to that. But, had you taken the time to gently explain the concepts to us savages (yes, I don’t have an EE degree either) and then gently explain how it might be fixed then you might have gotten a better reception. To some extent, I get it. I have a CS degree and we talk like you do too. It’s really tempting to throw out talk of Big-O notation and Red/Black trees and other stuff nobody cares about. But, we’ve all got to stop doing that.
Lastly, to translate what you said into plain English: There’s a difference between resistance and resistivity. Copper has a very low resistivity (which means that it’s general property is to readily allow current to flow) and so a large enough chunk of copper will have a very low resistance. The more cross section to your copper the lower the resistance. The longer your copper, the higher the resistance. Additionally, copper increases in resistance as the temperature increases. Because of these reasons you’ve got to be careful to size your bus bars appropriately to handle the current flow you are expecting with enough margin that it does not rise in temperature hardly at all when your usual maximum amperage is flowing. Thus, you should really increase the size of your busbars and conductors in order to lower the total resistance and heating effect.
Hey, on a plus side, my translated version of what you said is *shorter* than what you actually wrote.
LOL. I meant well and apologies to everybody if it come through otherwise. Your “translation” summarize my intent. The only thing I add there that large enough chunk of copper itself is not enough. The shape of that large enough copper is important in relation to the current flow. My style could be counterproductive but when I make a claim (why to do a thing in a certain way) I provide supporting evidence and in this case the laws of Physics related to this topic. I have seen way too many people making a claim without explaining the background.
… (and sometimes making a mistake like you did in your explanation about resistivity * cross section * length while the correct formula is resistivity * length / cross section. Details, verification are important)
Infra-red pistol grip temp guns are relatively cheap now if you’ve got copper and no senior engineer at your beck and call. Major insurance carriers use similar technology inside cabinets carrying 480, 4160, or 12,000. Better to know for sure than pay a claim. A loose bolt can ruin your whole day. Design, economics, craftsman ship and preventative maintenance all play a part. Edison and low voltage DC were all of the same era. Insulation is cheaper than copper now days. The utilities are quietly installing panels by the acre and batteries by the ton. They don’t use low voltage. Their nickel clickers make our first wives look like Mother Teresa.
In this case they are NOT important and the semantic attempts constitute what I always consider the online POSEUR WANNABE expert. I’ve spent 40 years now trying to reduce that crap to concepts and words that communicate effectively to normal humanoids. It’s not that I don’t know what you’re talking about, it is broadly that YOU don’t know what your talking about, and attempt it to mask it with obscure references to obscure formulas summarizing the obvious.
I usually term this having an “uncanny grasp of the obvious.”
In this case things that are already generally obvious to all our viewers anyway. I was attempting to REMIND them that current matters and at 48v, a quick napkin sketch shows there isn’t enough copper in the world.
IF you wanted to actually communicate, and again it would be of the obvious.
1. The longer the conductor, the higher the resistance and heat loss.
2. Increasing diameter/cross section can reduce resistance and heat loss.
3. The type of metal used can affect resistance and heat loss.
4. Heat causes increased resistance and can spiral out of control
Ergo we did not use aluminum bar but solid copper (better conductor) and silver (better conductor yet) clad at that. Your observation of its thickness is simply wrong. Our bars are 0.25 or 6.35 mm. And we did take the shortest possible length to the inverter in our design.
And all that is ENTIRELY the wrong direction to solve the problem. The correct design solution is to increase the voltage in the first place, reducing the current.
Mr. Enekes privately sent me a solution so PATENTLY ABSURD and ill informed that it would be impossible to implement in a cabinet twice the size of the PowerSafe 100. And THAT again misses the obvious – just go to a half inch thick bar. As the bars are already $247, that is pretty expensive, but about a third of the cost of his “solution”.
And so I offer this as a classic example of what I term a POSEUR WANNABE. Someone who desperately seeks attention as an EXPERT in an online forum, while offering essentially nothing in the way of useful information.
We have charged as high as 380 amperes now using those bars and with little ill effect beyond exceeding temperature IN the inverter and causing a shutdown. The problem is cummulative over time. At a much lower value of 110 amps we DID overheat the bars to an alarming 78C because of TIME. That was charging a 100kWh battery at 110 amps from completely discharged to cutoff to full and it took 20 hours. It was just over 1/4 of the max current, but because it was over a much longer period of time it did indeed become alarming.
The problem with poseur wannabees is that they cause innocents who like to refer to themselves as “researching”, meaning reading shit online, to spend time and money on useless or damaging strategies in their own efforts to tinker and innovate.
Indeed, Singineer is proposing a 20kw version of the same inverter. I am currently in the process of pointing out to them that there isn’t enough copper in the world at 48v to feed the monster. And that they should instead pursue a 20kW at the EV voltage of 320-400v. Oachim is almost never wrong. The correct solution to any problem is usually the simplest one and in this case that is the simplest solution to the problem – increase the voltage.
And we went through all that in EVs years ago which is how we GOT to 345v in the first place. The currents were just too high at 96v. And so I do NOT advocate simply going to 96v. You will find it a poor place to stop on the way to the same solution to the same problem.
I have been an electronics engineer, which is of course some different from an “electric engineer” for 40 years. During that same span, I’ve been waiting for something to load, something to save, or something to print on the software side.
Our viewership seems set on 48v despite my urging to adopt higher voltages. It might help to explain the WHY and so I have attempted to. But I have NO NEED AT ALL for self aggrandizement and view all who DO suffer that need with the utmost of both disdain and genuine disgust.
And do so again in this instance.
Collin was trying to be nice about it.
I am never patronizing and never condescending. But I am also often not so “nice”.
Would attaching the cables from the inverter to the middle (vertically) of the bus bars help? It seems like it would reduce the maximum current in the bus bars to 1/2 of that compared to attaching the cables to the top or bottom of the bus bars.
You know, it might. But we’d attach them from the contactor to the BOTTOM of the bar more likely.
Jack Rickard
Thanks for sharing the details regarding the inverter behavior.
Can you AC couple the solar system to your 345V-360V inverter like you did with the 12KW/48V inverter?
Jack, I am totally OK with 345V instead of 48V. But there is no cost effective, manageable alternative for 48V system, isn’t it?
I would like to note that Tesla battery pods in the powerpacks are 48V. With a twist of a DC/DC converter from 48V to 900V to the bus. (but how we can find cost effective similar strategy?)
Yes, we can and we have.
You have so many qualifiers in there I can’t quite make it out. We actually DO have a $3000 inverter for high voltage, but it is only about 5 kW. I am trying to get the Singineer guys to do a 20kW high voltage. But that would be a year away if they said yes today.
That IS the issue. The MPPT Charge controllers and inverters that are very low cost are currently all 48v. Our 20 and 30 kW high voltage are $15-$20k by the time we pay to ship 600 lbs 8000 miles.
And so as I said in the video. I get it. You like 56 lb logs. And you like inverters in the $2000-$3000 range. And you want to buy battery modules two at a time. I get it.
But the price to pay is current. And you just can’t get up to high power at 48v. For a modern house, I consider 12kW about right. But a largish house or light commercial operation that starts to look a little weeny. As I said, I’m just not into the 4kW level and if I were the Magnum Power unit works fine.
The Tesla battery “pods” don’t matter any more than the Tesla cells of 3.6v. The system is 900 volts. And the DC-DC converters are an interesting way to get there while providing isolation. Nothing more. 900 volts for large installations is MUCH better and over twice our EV voltage – and so half the current.
Our same 20 modules in series would be 500 volts and 12kw would be 24 amps. How cool would that be. But we are spoiled to death. I have just found you and had modified for your use a 12kw Inverter doing Tesla module voltages that will deal with AC grid power usefully to eliminate the auxiliary charger. That’s a couple or three MONTHS ago and we are pricing it at about $3000. What is the OTHER $3000 12kw inverter you can find me? Never mind the AC grid input, generator output and a LVCO perfect for two Tesla modules.
But yes. I am on quest for an inexpensive high voltage inverter. Right now the Sandi is as good as it gets.
And yes, we have done AC coupling with them.
The AC coupling is not a development. It is a discovery of something that has been right in front of people for years. But they were so steeped in the repeated and repeated and repeated lore of solar, that no one could believe it. Most still assume now that I don’t know what I’m talking about and it can’t possibly work because they’ve read that and been told that so many times. It is a FEATURE of using an H-bridge switch with a transformer. More elaborate devices may indeed not work. I don’t know
Jack
Mr. Rickard, have you seen this video? Someone converted an Audi to electric using parts salvaged from a Model S.
https://www.youtube.com/watch?v=IOYY_AlRWQA
Based on your comments on the scary dangers of cramming as much power as possible into as little space as possible, it gave me the willies to see 13 Tesla battery modules in a stack together, close to the driver’s seat, with a sheet of plywood as the protection. They said they don’t have the battery coolant system done yet, so they just try not to do anything that would overheat the batteries. It seems a tad… underengineered… compared to the Model S design.
It’s somewhat under-engineered in some ways, yes. For one – don’t run Tesla modules without coolant flow. The thermistors are on the coolant loop and really only tell you input and output coolant temperature. So, this guy was basically shooting in the dark. At least he had a laptop monitoring the module BMS boards so he was getting some faulty temperature data and the cell voltages. That’s better than nothing at all. Some of what he did was pretty nice – splitting up the motor driver and motor and making a custom adapter with a 10:1 reducer was pretty neat. Stacking modules with very little in the way of anything holding them down and using plywood isn’t quite so nice.
But, he had the coolant loop actually hooked up, just not working. Hopefully he has since fixed that. Now we just have to hope he fastened down the modules a bit better as well.
Actually he didn’t have a laptop monitoring the BMS boards. He had an Orion BMS monitoring the cells. Curiously inelegant. I thought it was kind of a shitshow. The placement and mechanical mounting of the batteries is a mess. A front end collision and you’re pinned to the steering wheel by 800 lbs of high voltage batteries? Not with me in the car. But the work to separate the inverter and motor and adapt it to a driveline was impressive. I’m assuming this was done to retain the AWD that way.
I don’t think we’ve ever done or advocated a battery installation in the passenger compartment. Perhaps the mini cooper, but they were in a metal box on steel rails.
The guy who built the car did state that AWD was working. Personally I would rather have fewer things that can break, but for this conversion, hooking up to the existing transmission and AWD system does seem like the way to go.
Jack, knowing that you area sucker for instrumentation, do you have a milliohm meter? I used to use one for the high current weld cables on the robots in the body shop. Its 120v powered, runs a current while measuring resistance through dual probes (4-wire). We would find bad wires from flexing, but mostly never met a connection that we liked.
Some examples here:
https://www.pce-instruments.com/us/measuring-instruments/test-meters/milliohmmeter-kat_40083_1.htm
Some guys would call it a megger. Ha, totally the opposite.
I am of the merger school and yes, there’s one around here somewhere. And yes, I’ve never met a connector I liked, and that is beginning to extend to connections as well.
MilliOhm meter is for high current conductance check
MegaOhm meter i(Megger) is for high(er) voltage insulation leak check
Mine was hand crank made in the UK. It died a natural death a while ago. Loved it.
There may be an option for a custom inverter, i’m working with an ASIC module from china, called EG8010. I am having some success with a 48V system that I started before I saw jack’s singineer inverter. (mine is 48Vdc to 240VAC, split phase, isolated, 7.5kva, proper sine wave). This relies on a 7.5KVA transformer. With higher voltage mosfets (or IGBTs?), this module can easily control them to chop up voltage from a tesla battery pack and go directly to 240VAC, i’m still on the learning curve and haven’t hit 7500w without things getting really freaking hot, I misunderstood what is happening between the inverter and transformer, but I have a plan going forward)
The controller modules are dirt cheap from aliexpress, the datasheet has a schematic to convert 400VDC to 220VAC, without a transformer, though it requires a rather large inductor/choke to smooth things out.
https://www.lz2gl.com/data/power-inverter-3kw/eg8010_datasheet_en.pdf
https://www.aliexpress.com/item/DC-AC-Pure-Sine-Wave-Inverter-SPWM-Board-EGS002-EG8010-IR2110-Driver-Module/32908448144.html
the catch here is that it can only do single phase, if you want split phase, then the easiest way to go would be with a transformer, which might replace a good chunk of the choke (could probably do a 4.7uH instead of 3.3mH) as well as provide full isolation.
Here is an example transformer that could help with this.
https://www.ebay.com/itm/Sorgel-Electric-Corp-25S3H-Single-Phase-Transformer-25kva-240-480-120-240-/122760570271
I should add that, while my system is 7.5kva, the real limit is in the mosfets and transformer. it would be easy to get 25kva if you had the right parts. (25kva transformer example linked above)
Nissan has in production in Japan Vehicle to Grid capable chargers for Nissan leaf Battery packs.
https://www.nissan-global.com/EN/TECHNOLOGY/OVERVIEW/vehicle_to_home.html
my understanding is that these leaf battery packs have a nominal voltage of 360Volts and have a 6 kw output.
So just procure one or 2 of these chargers and use a nissan leaf battery controller to fake out the charge into thinking your detached battery pack is connected to a car. I would think Nissan will be making them in large quantities soon and selling them at cost for awhile to promote their car sales.
How many leaf batteries are in junk yards now?
Best regards,
Gregg
and then theres the PIKA energy REbuss that runs at 380V nominal. Buy the battery and hack into it and parallel a tesla battery pack into it. 6.7 kW. 20Kwh battery.
https://www.pika-energy.com/harbor-battery/
I like that you are using the Raspberry Pi and screen. I’ve had very good luck with their little 7 inch touchscreen, and my favorite case for it is the SmartiPi Touch case from smarticase.com it comes with a couple of options for the hinged base, either a large foot for desktop use or a small foot for mounting to a wall or cabinet.
DallasMakerspace.org uses several of them around our building for information displays. I’ve documented them as our “Event Display Kiosk” in our wiki, and detail how we set them up for Portrait mode rather than Landscape mode.
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