Starting All Over Again

It’s December in Missouri. We endure short, dark, cold days now with ghostly winds and a heavy dampness. It is notably wretched. The problem with global warming is that it means different things to different people. Climate change is mostly frightening to those who have a good climate to start with – ergo the concern in California. Less so in Missouri frankly.

The new facility at 601 Morgan Oak St. has two massive heaters. I would imagine we will enjoy them thoroughly up to the first utility bill arrival of the new year. In the meantime, the house garage is too bitter to do much in and this has hastened our move down the street – where it’s pleasantly warm.

Of course, anything we need is down the street at the original garage.

This week, we do a bit on Positive Temperature Coefficient heaters. You would think you could buy a heater kit from a company that calls itself Canadian EV and do pretty well with it. They are, after all, in Canada. Doesn’t it get quite cold there?

NOT. The little system we put in Speedster Duh seemed like a true blue ribbon Champion when we installed it in July. In December, it’s pathetic. So we built our own replacing the ONE heater element in the “Canadian” version with three. Better. Not great. But better.

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The Mini Cooper Clubman, conversely, is working quite beyond my expectations particularly in the realm of environmentals. We had replaced our convoluted but very effective cooling system with a combined loop containing our 4kw glycol heating system AND using that to cool the Rinehart Motion Systems controller and motor. This is an absurd concept – attempting to control the temperature of two different things by cooling one, and heating another, with the same loop.

Surprisingly, it is working quite well – at least in December. We DO get some heat from the drive train, though nothing impressive. And the controller and motor DO seem to be maintained at an operational level of cooling – at least no shut downs. My only explanation is that the two components live in two different temperature climates. In the car, we find 65C to be quite warm. In the controller and motor, they find 55-60C quite cool. And the difference is the temp drop across the heat exchanger. That this would work surprises me.

Call me still skeptical until July. But meanwhile, reasonably comfortable in December. It takes a bit longer to heat up this larger loop than we enjoyed previously. But once warm, we can often turn off the 4kw entirely and the motor and controller seem able to maintain the temperature reached with the heater for some time.

Having Speedster Duh back is great, and in any event, Speedster driving in December is a bit of an extreme exercise. You have to really love a Speedster to want to do that in this climate.

So we’ve taken it as a good time to revisit the original Speedster. We were surprised to learn how much more power we had on the dynomometer with the original Speedster than Duh. But it was really impossible to compare apples to oranges largely because we had gone to a different transmission on Speedster Duh.

The original Speedster used a traditional 3.88 ring and pinion in the VW transaxle. With the Netgain motor, first gear was absurd, reaching the RPM limit of the motor at about 10 mph. Second gear was somewhat better, but really unnecessary. And third gear, while higher, seemed to put no strain on the motor taking off from a dead stop.

So in practice, we drove in third gear in town and fourth gear on the highway. A two speed.

This actually works pretty well, particularly since we have no regenerative braking from the motor. The car rolls very freely and I can coast for long distances using no motor at all. PLUS I needn’t use the clutch to shift between them. Simply quit applying power and move the gear selector. The synchros are more than able to deal with the mass of the electric motor. A very tiny “pause” between the gears.

But it seems very amateurish to have a four speed transmission with two useless gears. It is a Speedster, and shifting is part of the game.

So we pulled all the cells and boxes out, tore out a lot of our now known to be useless monitoring wiring, and have swapped out the transmission on a 3.44 R&P like Speedster Duh, which makes effective use of all four. We’ll take this opportunity for a general makeover.

The aging Kelly Controller is going to be replaced by a brand new Soliton1 1000 amp model. We’ve been wanting to try this anyway, as we are going to use two of them in the Escalade. The Kelly was advertised at 1400 amps, and we rarely saw more than 540 battery amps out of it. We had little in the way of cooling or heat sink on the Kelly and if it got hot, it simply shut down. We could almost always recycle it by turning the ignition off and back on, even while rolling down the highway, and it would then go merrily on. This happened but rarely. So we didn’t mind it terribly. But the Soliton will do much higher voltages (up to 340volts) and we have some ideas about additional batteries.

If we could get our voltage up to 144 volts, I think the Soliton will turn the Netgain into a screamer.

Since we have to remove the motor to change the transmission, we might as well try the NEW Netgain model. It is supposed to have better brushes, better cooling air flow from an improved internal fan design, larger terminals, stronger brush springs, some RPM monitoring options, etc.

We were stung by battery box sizing using the bulky Canadian EV adapter. We actually combined TWO different adapters for the Speedster Duh. We liked the Canadian taper lock coupler design and the EV Source adapter plate design which took up much less room, weighs less, and looks better. We had Cape Precision Machine basically combine the features of both into a third and new adapter design for VW transaxles and it worked out very well, allowing us larger rear battery boxes in the Speedster Duh. We need those in the original Speedster.

We actually fitted 16 180AH cells in the front compartment of Speedster Duh using an aluminum box Special Editions engineered for us. But they missed the measurement slightly and it was a problem. The cells also are perilously near the hood latch. So we are going to devise an EXTERNAL aluminum box, cut the fiberglass floor out of this compartment entirely, and lower and level the floor thereby. This should allow our 16 larger cells quite comfortably and we’ll use Eric Kriss’s layout therein.

We’re also going to attempt 11 additional 180 AH cells by use of a 3 inch thick tray that will mount between the cross members directly under the seat. This will comprise about 138 lbs of cells, plus maybe 30 lbs of aluminum tray VERY low in the car and directly under the seats. This should dramatically lower the center of gravity and reduce the polar moment of the car at the same time.

And then we are going to attempt ten cells in each of two boxes – one on each side of the motor. This BARELY worked with Speedster Duh and the AC-50 motor is actually slightly smaller, with much better terminal arrangement than the Netgain. I don’t know how this is going to go at this point frankly. We may have to lose two cells there.

So we should wind up with 47 cells total for 157 volts or 45 cells for 150. The larger number would give us 28260 watt hours for a theoretical very max range of 125 miles. With the additional weight, and with a more powerful drive train, we may not quite achieve that. But we should in any event wind up with a TRUE 100 mile vehicle in all driving regimes and with adequate margin to maintain our cell cycle life handsomely.

We’re planning some other upgrades with a Speedhut gage upgrade with a true GPS MPH Speedometer and a tachometer and fuel gage. We’ll add components for the EVWorks ZEVAII fuel gage driver and the daughter mode we worked out on Speedster Duh. We’ll probably keep the EVision display because Brain did such a marvelous job of incorporating that in the VDO combi gage case we had originally. And of course we’ll add our little Roving Networks box to drive our EVu software on the laptop.

We’ll do a 3 element PTC heater under the dash as well just as we did in Duh.

The result should be longer range, higher power, even than Duh. Blue Sky is the Soliton works out better than we hope and we actually have a tire burner on the dyno. We’ll have four smooth gears to deploy it.

And we continue to improve it.

The St. Louis Auto Show is scheduled for January 27-30 at the Convention Center in St. Louis. One of the things they have planned is an ECOCITY with alternative fuel vehicles. They have invited Gateway EV to provide some electric cars for attendees to test drive and ride in on an indoor track through ECOCITY. I’m not sure what ECOCITY is frankly. But we’re hoping to take two Speedsters, the Mini, and the Spyder to this event and get a feel for people’s reaction to them. I have to constantly remind myself that but a handful of people, including all our viewers, have ever actually ridden in one of these vehicles and felt what I feel every day. After over a year of weekly videos, it’s hard to imagine this is a secret, but in a very odd way, it is.

I have developed a deep and abiding affection for this pleasure car. I say that because I don’t actually consider it an automobile. The Mini Cooper is an automobile. It has air conditioning, heat, bluetooth, Sirius Satellite Radio, heated seats, power windows, garage door openers. The Speedster is a minimalist toy car. But it is great fun, and an iconic design.

There IS no other car, I am convinced, that is more of a head turner than the Speedster, unless it were the Spyder. I truly believe I could line people up standing on the HOODS of Tesla Roadsters to get a closer look at this car. What is even more surprising, is that kids and young adults here in Cape Girardeau just LOVE the look of the car. And they have no point of reference. They don’t know that it’s from the fifties and they don’t know even that it is a Porsche. But they still like it. The basic shape is just an iconic design from the house of Karmann. It will ALWAYS be a head turner. Year in and year out, generation after generation, regardless to the fashion dictates of the automotive industry. It is timeless. It has no year. It has no brand. It is a shape.

The Special Editions Inc and Vintage Speedsters have been VERY careful to reproduce these vehicles with utter fidelity to the original Speedster. It is the heart of their business and the better they can simulate the original, the happier their customer base is.

I’m not sure that applies in this case. We don’t make the original sound. We don’t drive like the original Speedster. We may be a new thing. And maybe we should let go of the old a little bit.

Where is all this going? We have broken into violent agreement with Special Editions repeatedly. They want to do the car. We want them to do it. But they have concerns about being on the hook for the battery pack. And in fact, their workers are a little bit afraid of TOUCHING the battery pack. There’s quite a learning curve on the electronic components, and particularly when we depart from off the shelf solutions such as the Canadian EV heater kit, and start having to fabricate our own. Instrumentation remains an issue. We haven’t got it all worked out yet frankly.

I said we would never produce the Speedster. And we won’t actually. The idea of Brain and I manufacturing cars is somewhat absurd. We’re media guys.

But we have changed the nature of the conversation with Special Editions. There IS a constant level of inquiry from people who want to just BUY a built Speedster. And we need a reply. At this point, I’m wondering WHAT it would look like if we built a few, say 12 a year. After visiting Bremen, I liked the look and feel of the father/son shop there, and the obvious pride they took in hand making cars.

Young Hauber has come to do an Escalade project. But he’s worked out well and seems happy here and he has a dream of building electric cars.

Special Editions meanwhile is striving for more control of THEIR process. They’ve had new molds made and are moving the body buildup and paint to the U.S. And in the Spring, they plan on introducing a new car – the Roadster.

A Roadster is actually a more deluxe Speedster. It has a taller windshield, more luxurious seats, a better top, and best of all, rollup windows. It’s a little heavier, and a little more expensive.

So we’ve been talking about what an electric Roadster would look like.

The first thing we need to improve on the Speedster is a lighter vehicle. When I ran the concept of carbon fiber reinforced plastic (CFRP) past Carey Hines, he was lukewarm to the idea. But he warmed up to it a bit. It would save about 300 lbs over the traditional fiberglass, but would add some $15,000 or perhaps $20,000 to the car.

We then talked about other weight savings and he did allow that some Arkweld/Wilmot aluminum brake components were available that would save 127 lbs, but were likewise expensive at $2500.

He started getting with the program and noted that really the frame COULD be done with aluminum, and would save another 400 lbs if we did so. More, it could be made to accommodate the IRS axle.

The Speedster uses the older and more traditional swing axle transmission with torsion bar for suspension. This is basically what the original Speedster WAS. But Volkswagen introduced a new independent rear suspension (IRS) system in about 1967 that really was an improvement in handling.

And the picture that emerges in my mind, and very nearly nowhere else, is of a 150 mile range Roadster that handles better than the Speedster, is 500 lbs LIGHTER than the Speedster, has more comfortable seats, roll up windows, more headroom with the top up, and of course, using the HPEVS drive train still accelerates better because of the lighter weight. We are also expecting some Curtis controller improvements in the next year, hopefully to BOTH a 650 amp and a 144 volt ceiling. Indeed, if we could put down a 90kw, 1500 pound, carbon fiber aluminum Roadster, it would be a thing beyond.

Of course, it would cost $80,000 freakin dollars. For a “pleasure car”. A wine country fair weather convertible. And so we could be in the car building business, without having to build very damn many at that price I would bet….

And so this is the stuff of dreams…. but as drive components and batteries improve, so does the dreaming….

Jack Rickard

44 thoughts on “Starting All Over Again”

  1. I’m in the process of upgrading my Porsche 914 conversion. The heaters seemed to work fine, but I still wanted to feel warm without consuming so much energy. I actually just used two hairdryers for heat. I mounted them to the firewall near where the original heat tubes came up and then connected a heat tube to the hairdryer and inputted the tube to the original location for the heater controls. this allowed all the original controls for directing heat to the floor, passengers or windshield to remain functional, and I have instant heat. 2 1500 watt hairdryers worked well, but I am adding heated seats to my car and I believe I will end up using less power by having heated seats instead of heating the cabin air. Hairdryers will remain, but I expect I’ll be using them less.

  2. Also, have you heard any more from DBM and their Kolibri Alpha Polymer battery? They had that record distance run in the Audi and now things have gone silent.


  3. Hi Jack,

    Fun show! Can’t wait to see how many batteries you can cram in Speedster Sr! You mentioned during the show twice that CALB would be selling directly in Pomona, which is great news. Could you share the link for ordering?


  4. DBM. Unobtainium for the present. Another Power Point Presentation product as best I can tell.

    Dear Mr. Rickard,

    thanks for your enquiry.

    As a manufacturer of energy storage systems, our world record demonstrates the state of today‘s technology. The trip counted as demonstration of the performance and efficiency of our KOLIBRI technology and is now the prelude of bringing our technology even further.

    Our core business is the development and production of high capacitive and intelligent energy storage systems with outstanding efficiency. Our batteries are nowadays used in the logistic sector and as power plant for applications.

    As soon as we see the possibility for joint proceedings in the EV-sector we will get back to you.


    Corinna Hosemann

  5. Balqon/Thundersky. This is interesting. But I think most have missed the point. The point is not that Thundersky will only distribute through Balqon in the U.S.

    The point is that Thundersky now OWNS Balqon ENTIRELY and is COMING to the U.S.

    I would imagine Balqon, a manufacturer of heavy electric trucks, is about broke. The CEO is leaving immediately and being replaced by the CEO of Thundersky if I read it rightly.

    This looks like a Thundersky reponse to CALB ‘s new CALIB warehouse in Pomona. Basically, Thundersky has just assumed a stance in the U.S. complete with warehouses and electric trucks. For about $5million total.

    This is very interesting JRP. It means we have won in a way. We have now purchased enough cells that the Chinese want to quit with the wire transfer and 12 week lead times, and actually come here and do business – take Amex and ship in a week and stock batteries here and so forth.

    And I think the James Morrison episode has had a salutory effect. LiFePo4 sales basically stopped with that incident and have been trickling since. They do recognize at least an infant market and both companies are moving to protect it.

    No the exclusive distribution agreement isn’t any threat at all. They can then in turn sell to whomever they might. But it gives them a U.S. presence, storage, THEY can worry with the import duties and shipping particulars. We’ll be able to pick up a phone, call someone in the U.S., speak a little Chinglish, and get batteries the next week.

    It’s all good. You’ve bought enough cells to get their attention. They don’t want you to quit now, just because Americans are all a bunch of crooks…

    Jack Rickard

  6. Hacking the aux shaft. It would not be a problem, but it wouldn’t ease our install very much. The problem is getting the motor case past the rear frame. Then there IS the problem of getting the aux shaft past it as well. But it all seems to go MUCH easier since we now have a lift and this $200 transmission jack.

    We did this originally with a cherry picker from the top. NOT fun.

    We aren’t actually using the aux shaft. But we might want to in the future – like if we added air conditioning.

    Jack Rickard

  7. Mr. Davidson:

    Sounds like a fantastic idea. I’ll tell you what, why don’t I build the $80,000 Speedster then. And you can build the one with the 50 mile range.

    Maybe use an older Speedster and put old lead acid floor sweeper batteries in it. You can probably use a used forklift motor and do just as well. Pickup a used Curtis 1231C pretty cheap. A resistive potbox on the accelerator. Hell, you can just use one of the lead acids to power the 12v and pickup an old Lester golf cart charger…. I think it’ll fly….

    In fact, I’ve always wanted to play with one of those old mercury “valve” rectifiers myself as a charger. That would be cool. We can have our girl friend paint ELECTRIC CAR all over the side of it with some house paint, she’s very artistic you know. And then everyone will know we are cool, and maybe spend a little extra on a vanity plate that says something classy like GAS SUCKS or GO GREEN.

    We can probably do the whole thing for a few hundred dollars and then write a book on how others can too!

    I can certainly handle a 50 mile range myself. So if I build a car with a 150 mile range, I’ll use the cells so little they’ll likely last 20 years and 500,000 miles. That’s four interiors and three paint jobs.

    But if all you need is a 50 mile range, it’s ok to set your sights low. I always say DREAM SMALL. That way you’re never disappointed, and best of all, you can always AFFORD it and your wife will NEVER be MAD at you. Yah. That’s what I live for.

    It’s all about that commute. Get back to the cubicle city. Get home. I live for that. Cubicle city. Home. Cubicle city. Home. Make sure the wife’s not mad. Cublicle city. Home.

    That way, at the end of my life, when I’m in a white room full of white people in white uniforms, all very concernedly bent over me trying to figure out how to get the government to pay the uttermost farthing for the very last possible procedure before I pass from this world, at least my wife will be happy and I was able to afford it all. My friends in cubicle city will all be delighted it wasn’t them. And all is right with the world.

    Here’s another great bumper sticker we could do: SETTLE FOR LESS. Or how about SAVE THE PLANET – STAY HOME A LOT.

    That way, we wouldn’t be crazy at all. Not at all. AND we could have our 50 mile range 4000 lb Speedster whipping down the road at 28 mph with the wind in our hair, livin free and getting down with our bad self….

    Absolutely. A carbon fiber body, an aluminum chassis, aluminum running gear, and an obviously overbuilt drive train with very EXPENSIVE batteries is not what we’re after here at all. It just doesn’t make good sense.

    There is a guy in Austrla named GAV – he has a wife – very happy girl I understand. Of course, his EV was banned from the roads there for being a POS so he had to sell it. And he used the money to take HER on a vacation to Fiji so now she’s REALLY happy. But before he did, he did a whole series of very instructional videos on YouTube and I think you would find these much more satisfying than our long boring diatribe on electric car stuff. He’s young. He’s hip. He’s got it together. Very happy wife.

    Jack Rickard
    Having a rough start this morning…. can’t get my wheels to stop spinning in the sand….

  8. What a response!

    John Davidson,
    I don’t think this site is really about Project Forkenswift type cars or those silly, ugly cars that arty farty futurists draw up…. Massive bubble canopies, tiny little wheels and green paint. These people essentially point to each other. They HATE cars!

    This is about the drive, The dream. How one feels when they complete a build. Its a hobby. An attainment of ones self worth not to mention the exquisite pull on the senses to drive such a vehicle!

    What gets me each time an electric car switches on and glides off is the smoothness and easy silence. Heard how quiet that mini is?

    As you see here. It’s not about saving or making money, its a lot more.

    The bread and butter car you are talking about would be a cute car with say, an LMC pancake motor. It would pay for itself in a couple of years. You can do it. 🙂

  9. Yikes….well you got it off your chest. I want to say. In two years time we could be looking at a man put together a lightweight carbon-fibre car with over a 200 mile range. Heck, in four years it could be over 300 miles. Who knows….. who knows indeed. Unless of course you build it.

    Padraic (Dreamer)

  10. A forklift motor and a 1231? Wayyy too upmarket. Best of all is an old shunt wound aircraft starter generator. Who cares if its only rated to 1% duty cycle. For a controller you need some old forklift contactors and nichrome wire salvaged from electric heaters found in a dump. Mount it all on some scrap wood with big nails.

    Now the batteries. Floor sweepers use genuine deep cyclers. Pppfffttt! Just use starting batteries. Spend a month driving around garages collecting them , then another building a desulphator circuit from plans bought on ebay. Job done.

    Adaptor plate can be made from wood to keep with the green , renewable theme. Cut it out of a table top. Crimp lugs are for loosers. Get some copper plumbing pipe , a hacksaw , drill and a hammer. Reuse that pile of household electrical wire. Who cares if its too thin just use 400 strands.

    For the piece de resistance reuse the alternator belt driven from the motor as a dc dc. Forgot the brake vac pump……..oh yeh get one of those little 12v tyre compressors , take it apart and invert the reed valves. Instant vacuum pump.

    Now for the charger. Fortunatly , the absorbtion voltage of the “traction pack” will coincide neatly with rectified 120vac. So get a coffee can , bridge rectifer , a neon from a washing machine and a big switch. To be really snazzy use a mechanical central heating timer to be able to brag to the boys in cubical town that you have an “automatic” charger. Optional extra is a home base “fast charger” based on a rewound welder transformer.

    The heater is easy. Get one of those old 2 bar electric fires from the 60’s with the rubber and string power lead. Sit it on the passanger seat.

    Of course the whole “experience” will have been recorded for all to see on super 8!

    Damien Maguire

  11. Yada Yada Yada, boys…

    Two points to advance the discussion:

    1. The EV power system is expensive, but it lasts a very long time. I’m not playing the “show an accountant why he should have an EV” card here, just pointing out that the motor is probably good for at least one lifetime of driving, particularly if its AC or BLDC. Even a series DC motor is going to last through several daily driven vehicles. The Soliton and Zilla controllers are quite sturdy, too, as are the best of the other components. Its just a completely different game of what wears out.

    Even the worn battery pack will go from the car into the garage as a mother bank to support rapid shuttle charging, so it isn’t wasted, either. Its a lot of up front expense, to be sure, but the high quality stuff is largely extremely durable. This is less the case with scrap forklift junk, but it is also remarkably hardy.

    This is a great thing, particularly to those of us who are car hobby guys and used to REALLY expensive racing parts that are often disposable. In the EV end of the hobby, you buy a nice drive system, and you move it from car to car. It is actually easy enough to do this that in northern climates one could have two chassis, and swap the expensive EV bits between them winter and summer. I’m thinking the speedster could sit out the cold months in the garage while a well-finished VW kit car coupe like a Puma, Ventura or Bradley GT II could run on the motor, pack and controller all winter long. Each would have its own cooling and environmental system optimized for its operational season, and you’d now have two cool “third cars” and year-round happy EV motoring from a single drivetrain.

    Just an idea, but my underlying point is that these EV systems are truly an investment, maybe the only thing that’s really like an investment in a car you actually drive, and you really need to think of the apparently high purchase price (which just isn’t that high compared to late-model hot rod parts) in light of their durability.

    2. Jack, the speedster you describe COSTS about $80k in parts; you can’t build and sell it for that. In the standard automotive manufacturing and distribution model (as outlined by Walter Korff in Designing Tomorrow’s cars, among others…) it would cost north of $150k, with 25% going to the dealer/distributor, 15%+ to taxes, and fees of various kinds, leaving 7.5%-10% profit per unit with the manufacturer.

    This is how the car business is done. Yes, you might be able to beat it around the margins by off-loading the engineering (using pre-made components) and limiting the business to one model, but you lose that gain on the economy of scale side, so you’ll have a hard time escaping these numbers.

    This is a primary reason Tesla isn’t using dealers. By keeping the 25% of the price relating to dealer distribution in-house to the OEM, there’s another profit to be made selling and supporting the car. Other OEMs, particularly BMW, have been flirting with this model for years. Anyway, the underlying point is that you need to think of that $80k pile of Speedster EV components as a $150+ car, or it almost certainly won’t be a successful automotive start-up.

    Just my 2 points…


  12. Tom:

    Good points. Not sure I’m on board with all of them.

    Yes, a car now costs what a house used to. And I’m starting to think of them that way. You don’t trade it in every three years. You just redecorate. And the cost of a very high quality paint job, or a complete interior, don’t even approach the sales tax on a new car.

    Yes, you hot rod guys are used to custom low volume shiny parts. And I like the hole gestaldt of the custom rod thing, I just think it should be applied to quieter vehicles that make no smells.

    Our trip to Bremen was an epiphany of sorts. I’m not talking about being Tesla or GM. I think there’s still a place for small car shops – after the fashion of a hundred years ago. Here’s a guy and his son that have been living pretty well doing what they love for 27 years. And there isn’t any $150K thing going on there. I see Beck Speedsters fully done and with engines all the time at $28,995. Pretty tricked out ones go in the low thirties.

    I’m picturing carbon fiber aluminum at 500 pounds LIGHTER than what we’re doing. I see the roller coming in around $50K. If we use the very best parts we’re at $70K and I think we can put them out the door at a modest profit at $80K and it be a car that will last a lifetime, maybe two.

    We’re not tooling up for anything. We’d probably do a dozen cars a year.
    No dealers. No nothing. Half down to order and the other half on delivery 6-8 weeks. It obviously wouldn’t be for everybody, but that’s a good thing. We can’t do 10,000 cars a year. That’s a different kind of business.

    But it also wouldn’t be for those looking to commute to cubicle city 50 miles per day to save gas money.


  13. Nah! Back to cubical city 😉

    Load balancing and those theoretical spare batteries Tom Alvary mentioned. If we live long enough to gain a spare pack and/or have spare traction capacity. Buying in cheap electric at night and using the battery pack through an inverter during the day is maybe a winner for us with the ev-jeebies :).

    On a standard rate in the UK we are speaking of 7p/kwh at the absolute cheapest rate. If we contract instead to the cheapest “economy 7” for the best night time rate, we have: 17.8p/kwh in the day and 2.93p/kwh at night. Nearly a 15p difference. Let the fun begin…

    An EV connected to the inverter in the day. I quite like the idea of half price electricity when at home. If we have a single dial meter then lets make it run backwards on the daytime rate. Why not? Thats approx 15p/kw (less conversion inefficiencies and life) for every kwh profit for your pocket.

    We could be talking ~£5000 ($7000) p/a.

    I don’t know about you guys but that would increase my EV grin somewhat. However, there are some caveats and variables……

  14. OK, Jack, let’s work your numbers backwards:

    If you do one car a month every single month, and you’re clearing $10k on each one, is that really enough to float the enterprise?

    Let’s say Mr. Hauber gets very, very good at assembling these cars, and he can do them on average in 25 hours- total. Including inspection, road testing, everything. Let’s also assume it takes another 10 hours of dicking around, on average, to store, sell and support the car. (This support number is low and thorny…) I’ve left off the time to write the manual, do the corporate paperwork, insurance and regulatory compliance, because that’s one-time and you can just buy it as well as doing it yourselves.

    Anyway, call it 35 man hours and $70k of capital (not including the tools or shop) to make $10k. Not bad money the way you are thinking it, unless you have a single problem that takes time and money to fix. Two or three of those and you’re under water.

    Still, it could be a good start for Matt. All kind of comes down to the regulatory requirements for me. Carey Hines could probably tell you all about how his distributor/assembler customers handle that. I just don’t think there’s enough margin there to support more than one guy doing it part time, so even though its a nice way to get Matt into his dream of building EVs, its not going to support him full-time.

    That’s OK, too, just know these numbers are extremely tight for anything more than sustaining the effort to put these cars on the road. Again, that’s fine, and my point here isn’t really for your team, Jack, but for all those other guys who want to build EVs for a living: Don’t do it this way. Tight margins on a capital intensive build is only a good recipe if you have staying power and don’t care too much what you earn making the cars.


  15. M1AWS:

    Well, all true….but…..

    I think the point of going to the trouble to use a retired pack and a controller to charge your cells is your cells ALREADY are quite capable of an 80% charge in 20 minutes. The problem is where to get that amount of power.

    The “mother bank” concept is to charge slowly from the wall – yes during the night is best. Then, at any time if you need a quick fillup, you can swing by the house for a glass of tea and a 20 minute DUMP from the mother bank to your car pack. 300 amps is not a problem in this case.

    Ostensibly, this quick charging reduces cell cycle life moderately. But an occasional quick charge shouldn’t hurt anything.

    The obvious way to do this is to use an old controller. Setting up circuitry to actually do a CC/CV might be interesting, but realistically, you are just wanting to dump some power into a nearly empty pack for an 80% recharge. So it can be pretty crude.

    Jack Rickard

  16. Thanks for reading my mail Jack. It’s not a very serious post but it might have some payback. I suggest using/fooling the electric company/Gov’t that you have a home solar plant, then collect more state grants and have the perfect excuse to feed the grid during the day.

    80% DoD is like 5% less than the advertised rating. I’d say they were like new! Can’t see me getting hold of a bunch of Lithium’s in my prozac nation though.

    Considered an inverter straight out of the car would be good enough. I worked out my average electric bill is 500wh continuous. It would need say, >9kwh pack to meet the charge for me alone!

    Charging up, I would do this as slowly as practicable. It’s easy on batteries, electronics, the electric bill and charger cost.

    But you have already said this Jack. I just wanted to say it my way. 😉


  17. Jack,
    I am very curious why anyone with Lithium batteries would use a BMS. My 50 TS180AHs balance themselves. As you have said these things are amazing. I charge them up to 3.7 (a few go all the way to 4 but still well below the 4.25 suggested by TS) but after driving 1 block EVERY SINGLE CELL IS AT 3.34V. Truly amazing.

  18. Gavin,
    Just to be accurate they aren’t really balancing themselves, what you’re seeing is that pulling some power from them takes them out of the steep part of the curve where voltage differences show up and into the flat part where they don’t. They are still unbalanced, but as long as you don’t overcharge or over discharge them it just doesn’t matter.


  19. That’s right, JRP3, but we need a more precise definition of “balanced” so that we can continue the discussion without talking past each other.

    Using the same word, but not talking about the same thing is the root of a lot of disagreement about these batteries. The rest of the disagreement comes from a fundamental misunderstanding of what it means to have the cells “balanced” to begin with.

    First, I propose a better definition of BALANCED as applied to these prismatic CALB, CALIB Thundersky, Winston, GBS or whatever label and flavor you like:

    ‘A pack is considered “balanced” when all the cells are at 50% SOC (State of Charge) at the same time.’

    This seems to be the only actual and workable definition of “balanced” we can use. Note that this definition of balanced has nothing do to with observed voltages, nor with the capacity of the cells, which is quite variable. There is no practical way to equalize or compensate for capacity variation between cells in a pack. This is the core folly of a BMS as a “battery maximizer” which is much of what people are intending when they talk about “balancing” their lithium cells. Its just a the wrong use of the word balance to describe something else.

    “Balancing” can only meaningfully be defined as having each cell “balanced” at its midpoint SOC at the same time moment that all of the other cells are also at this 50% SOC. Why 50% SOC and not some other point? When every cell is at 50% SOC, each has exactly half its capacity left, even though that’s a different amount for every cell within the pack. Simply, this is the ONLY point in the charge/discharge curve that you can reliably orient a group of different capacity cells so that all the charge/discharge curves are perfectly nested inside each other, with the smallest capacity cell being fully charged AND fully discharged first.

    Jack’s harping about not touching newly delivered cells is all about this 50% SOC point. He seems to know that they are shipped in this condition, prepared to this exact state of charge in a highly automated and reliable way, and so long as your batteries are from the same batch and have never been wired up, they are all either at 50% SOC, or all (presumambly) slightly self-discharged from that point. That’s great news, because its actually quite a tedious process to hit the 50% SOC mark for each cell, because voltage is a poor measure of SOC on the flats of the charge/discharge curves. You establish that point in a battery of unknown SOC by fully discharging it, fully charging it (and measuring the Ahs it takes) to full capacity, and then discharging half of those Ahs to get to 50% SOC. It will be a different amount of Ahs for every cell, since they vary in capacity.

    Note that 50% SOC is the only point at which the cells within a pack will all have the same SOC. Because they differ in capacity, they will diverge in SOC (and voltage) as the overall pack SOC moves away from 50%. This is the hardest part of “balanced” to get your mind around. A perfectly balanced pack will usually have all the cells at a different SOC, and the widest variation in cell voltages at the highest and lowest pack voltages. Counter-intuitive as it might seem, this is not only completely normal, IT IS THE HALLMARK OF A PERFECTLY BALANCED PACK!

    {see next post}

  20. {continued from previous post}

    Once you really get your mind around this definition of balanced, you can see why “top balancing” and “bottom balancing” to a common voltage isn’t balancing at all, but rather forcing an imbalanced charge onto the cells. “Bottom balancing” is surely safer for the cells than “top balancing,” but NEITHER is balancing the cells at all.

    If a pack is actually BALANCED with all the cells at 50% SOC, you then have the maximum capacity of the pack accessible, which is the number of cells times the lowest capacity cell. Since the lowest capacity cell will hit the knees of the charge and discharge curves first, you also have the greatest margin of safety with every other cell, which won’t go over either knee until after the lowest capacity cell does, keeping all the other cells safe and perpetually slightly undercharged and underdischarged.

    That’s how these packs can be safely driven for many, many miles with no cell damage, minimal monitoring and semi-annual charge adjustments to collar the occasional wayward cell.

    A “Balanced Pack” must therefore mean that the cells are balanced on the midline between charged and discharged at the same time.

    If we could agree on that definition, we’d be WAY down the road to people both understanding how these batteries work, and why it isn’t worth trying to shuttle charge around between them, and why equalizing voltages among cells at the charge and discharge curve knees is counterproductive and risks damaging cells..

    We wouldn’t have so many fires, either, because it should now be clear that you can safely charge a balanced pack to the overall voltage at which your lowest capacity cell hits your chosen cell voltage maximum. Jack needs to chime in here with the facts on whether the cells are stable enough that this is repeatable (in other words the same cell hits the knee of the charge curve first, and at about the same overall pack voltage, provided the current going in at that voltage is about the same in every charge cycle.)

    This does indeed seem to be what Jack, TomW, JRP and others are seeing, but I’ll leave it to them to confirm the basic principal and definition:

    A prismatic cell pack is considered BALANCED if all the cells within it reach 50% SOC at the same moment. Its simple, but the simple explanation is usually the better one.

    Do I have this right, Jack?


  21. Tom:

    Not only do you have it right, but you have put it very succinctly and quite accurately. The only exception I might take is for the “occasional wayward cell” albeit the advice is good.

    There are no magically “wayward” cells. We’ve actually had several. That’s why the advice is good. But EVERY one of them was the direct result of something dumb we actually did to them.

    1. Expanding our pack with new cells without considering the balance situation.

    2. Time and AGAIN time we have allowed what I call “parasitic loads” form usualy instrumentation to bleed off a few cells while not others because “how much can it use at 20 ma.” Over five or six months? Oh, 15AH or so.

    3. Cell terminal degradation – looseness and corrosion. Be vigilant.

    Beyond that, the implication that some cells just wander off has no empirical evidence beyond this” I HAVE actually had what looked like a good cell right out of the box discharge to zero volts in teh car and never recover. Some just come that way. Perhaps 2 out of 400 so far. Manufacturing defect. This shows up immediately.

    Jack Rickard

  22. Just from the point of view of maximising capacity, surely it doesn’t actually matter where cells are “balanced” (top, middle, bottom) so long as the same (weakest) cell is the limiting factor on both charge and discharge.

    From a pack management viewpoint, Jacks point (if I have understood it correctly) is that with Lithium chemistries it helps to have them all lined up at the bottom because if all the cells run out of steam together, none of them are in a position to bully any of the others into cell reversal.

    This is a departure from lead acid. I believe that there is no alternative to top balancing for VRLA (AGM/Gel) batteries as chronically undercharged lead-acid cells sulphate – which might explain why top-balancing has been assumed by most of EV-land. Lithium is different

  23. Nope, sorry, John.

    One real beauty of this definition is that its so obvious once you really understand the characteristics of the batteries, and your reaction to it reveals whether you truly understand the whole concept of how to put a pack of these cells together and use them or not. Clearly you don’t.

    I say that because if you don’t agree with my post, or you have some technical disagreement you need to make with some part of it, as above, then you don’t really understand these batteries. Its that painfully simple of an idea.

    You are dragging something you know about other chemistries into your idea of these batteries, and its leading you astray. Balancing these cells into a pack has nothing to do with voltage or chemistry, and Jack’s promotion of bottom balancing is only as a solution for safely marrying a pack of diverse cells without actually having to balance them. Equalizing cell voltages doesn’t balance the cells or the pack AT ALL. If you don’t understand why not, that’s completely OK, but it isn’t open to debate.

    Reread my post. Watch Jack’s videos again if you can. Watch Professor Whitacre’s whiteboard lecture again. Ask more questions. Hang in there; there’s a really, really cool reality about these cells just on the other side of your current understanding.


  24. mmmh, I’m going to state the obvious from what I have read above….apologies. It seems that if we have a string of cells (identical capacities) that are balanced, they are inherently equalised. That is, if the discharge curve of these batteries were superimposed it would look like we have one curve for one cell – with my perfect, imaginary cells. We have two words here: balanced and equalised. If we are dealing with a bunch of cells that are not “in string” – if that is the correct terminology – well then if our pack is balanced, the batteries are not equalised once we are off the linear portion of the discharge curve. That seems to be the confusion, people think that my imaginary, perfectly balanced cells are “out of balance”, when ironically they are balanced (according to Tom’s definition) but are not equalised when say the pack is charged. To pile on more irony, in an attempt to “balance” the cells people are actually unbalancing the cells. But an unbalanced pack is not necessarily a bad thing if the cells are equalised at the bottom. I use the word equalised not balanced.
    I’m going to finish now, there’s no point in repeating the above. But I want to talk about discharge curves for my imaginary cells above. I have to imagine them because I don’t have access to these cells to test them. I remember E-Mailing Jack saying: I’d love to see more results of cell testing, but I know you don’t have the time. Well this is what I was talking about.
    I have already mentioned my perfect string of cells; the composite would look like a single curve.
    My second pack of cells which are different put perfectly balanced, the composite curve would be very different. Along the linear portion the line will be thin, but towards the fully charged and discharged portion of the curve the line will begin to thicken slightly before splaying out to different lines at each end of the curve.
    Now, what if we equalise the pack at the bottom. What will the composite curve look like? Here it is like a high jump, all the athletes are starting off at the same level, but they are going to jump to different heights. The curve at the bottom will look like its one cell until we begin to climb. Unlike the above curve the line may begin to seem to thicken for longer before they splay into different lines. So we start off with one line at the bottom, which splays into a few, or many at the top. This depends on the number of cells, differences and the resolution of the measurements etc.
    For a top equalised pack it would be the opposite. One line at top, spaying into many at the bottom.
    this is why I would like to see more test. I’ll do some research now that I’m off.


  25. John:

    I agree broadly with what you are saying here. I call this thinking from the lead acid pool. Pb cells do indeed buld up a sulfate layer directly on the plates and this crystallizes (hardens) if they are undercharged. There is no penalty in overcharging them as they simply outgas a bit of hydrogen and oxygen. And so overcharging lead acid cells IS how you “balance” them as it has come to be referred, but also how you ensure that all cells are fully charged and avoid sulfation, which diminishes capacity.

    Once you become familiar with this concept, it is VERY hard to let go of. I’m having a much easier time with people new to batteries entirely and simply cannot get old lead heads to believe it even if they tentatively do it correctly with the lithiums. It is very ingrained.

    The cells arrive from the factory at more or less the same 50% SOC. IF you don’t monkey with them, or use some and not others, etc. and simply install them as a pack and treat them as a pack, they will be fine.

    The differences in capacity in a given delivered set of CALB or TS cells at this point is pretty minimal, and so you can say you have a pretty well matched set.

    But they DO still vary to some degree in capacity. And that capacity difference is ONLY exhibited where you can measure it effectively, and ONLY an issue really, at the very top of the charge, and at the very bottom of the discharge. Avoid those two extremes, and you’re just all good to go. And no, they do not appear to “drift” over time. If they do so, it is so minimal as to be a non issue.

    HOWEVER. If you do balance at either end, ie bring them to the same exhibited voltage at the top or bottom of the curve, you have EXACERBATED the difference in capacity at the OTHER end, EITHER other end.

    This really isn’t that much of a problem if you have moved those differences to top of charge. You want to make sure you do not overcharge any ONE cell after doing this. The easiest way is to undercharge the whole string slightly. ANd indeed, there seems to be some benefit to undercharging ANYWAY with regards to cycle life, so why don’t we just do that as a matter of practice and give up a mile of range to the battery gods in the name of cycle life.

    There IS no cell reversal at the top. There is no such concept. All you can do at the top is overcharge, and indeed that is bad, but easily avoided.

    At the BOTTOM of the discharge curve there lies beasties. Cell reversal is where we DRAW current from a pack and every cell has to provide exactly the same current as every other cell, whether able or not. Any dissenting cell is simply overridden by the many and the more powerful to drive the current through it. We call this cell reversal and it is normally fatal to the cell.

    Worse, in driving the car, which is how we reach the bottom of the discharge curve, we are not talking about minutes and 12 or 15 or 24 amperes. We are talking about 100 or 200 or 500 amperes and so we are also moved from minutes to seconds.

    And this is why we don’t EVER top balance. It’s ok to bottom balance and indeed with a mixed bag of cells or when replacing cells, it is much easier than the impractical task of bringing all cells to a 50% SOC.

    The good news is there IS no drift. There IS no sulfation. There IS no memory effect. You don’t have to fully charge these cells EVER and you don’t have to fully discharge these cells EVER.

    This is ideal for an electric car. You plug it in whenever you can. And you walk away. And even if it’s only charged for twenty minutes, you can unplug it and walk away. And the more you do that, the better they like it.

    Jack Rickard

  26. Padraic:

    Your image of a splayed curve at top and bottom is reasonably accurate and somewhat useful. A couple of items.

    1. It’s a natural part of the game. No fix needed. You are NEVER going to get more capacity than the cell with the least capacity anyway.

    2. If you do ANYTHING to eliminate the splay at one end, you INCREASE the splay at the OTHER end.

    3. If you just have to fool with it, minimize the splay at the bottom of the discharge curve to eliminate the possibility of cell reversal.

    4. Don’t, in ANY case, overcharge these cells and particularly do not overcharge them unattended.

    You need a good charger that is very reliable in measuring pack voltage and very reliable at terminating the charge process if that voltage is exceeded. Period.

    Taking a cheap or existing charger and cobbling on negative temperature coeeficient semiconductor components to make it smart is NOT a good idea. If they fail, the “dumb” charger simply continues to charge, and you will wind up burning your car to the ground, the ship its in, the garage its in, and possibly the house you’re sleeping in.

    When that happens, cast around for anything you can find to confuse and obfuscate your mistake. This can make it easier to collect insurance and you’ll avoid the embarassment of having to admit you were on the wrong side of this BMS deal from the beginning. Better to let others burn as well than to admit a mistake. Maybe it was that your cord wasn’t UL listed:?

    Jack Rickard

  27. And that brings us to the rest of the story. So Jack, don’t I need a “BMS” to tell me when I’m on this discharge curve so I don’t overdischarge my cells and cause cell reversal?

    Yes, and no. You DO need some way of detecting that you are running out of gas and you do need to stop driving teh car before that happens. It would be nice if we could fix the car where it quits running before that happens.

    And the approach we have come to is counting ampere hours. Kilowatt hours would do as well.

    Actuallly voltage would do, but to maximize cycle life, we would ideally limit to an 80% discharge. And voltage is really pretty useless until 90% discharge. So AH and kwH are best.

    The ultimate hysteric is individual cell level monitoring for low voltage. In itself not a bizarre concept, but monitor it for WHAT and what do you do with the information.?

    Dmitri et al foolishly look at the spec sheet and proclaim AHA we have it, 2.5 volts is the cutoff voltage so that’s it. Eureka!

    Well, it is not that simple. You see, that 2.5v is the cutoff at 1/3C – standard discharge rate. With LESS current, the cutoff would be HIGHER and with MORE current, it would be lower.

    I actually know of an outfit that is trying to SELL electric cars to people who have one little problem, they can’t get the cars to DRIVE. They have their own BMS design. And they actually cannot figure out why when they drive down the road 4 or 5 miles the car just magically quits. When they check all the cells, they are fine. If they drive another mile or two, it quits again.

    They have set their BMS to disable the controller if any cell reaches 2.5v. Guess what, under 200 or 300 amp loads, they ALL reach 2.5v –and below. This, on a FRESHLY charged pack.

    It is what it is. And they go lower at 500 or 600 amps.

    If you want a sanity check on your pack, to make sure you don’t have any failed cells or failed terminals, the BEST we have been able to come up with is some variation on Lee Hart’s balanced bridge design. That is, compare the voltage (whatever it is) of the bottom half of the pack to the voltage (whatever THAT is) of the TOP half of the pack. They should basically be the same within a volt or so. And this should hold true at ALL current levels. If 49 cells droop to 2 volts at 500 amps, and one goes to zero, you probably have a problem. And it should show up in this simple comparison.

    This could be a simple LED that lights. The best would be some form of bar graph or needle that indicates degree and trend.

    If you see this creeping a bit as the pack discharges, probably no harm no foul. But if it is normally centered, but pegs left or right on acceleration – cell problem. If it normally centered at stop light. And suddenly it’s pegged under same condition, problem.

    What is the problem? You don’t really care. You can chance it and drive home if you are close. Or call a flatbed and ride home on top. I’ve done it. It’s $50 and not that big a deal compared to $10,000 in batteries.

    Once in the garage, THEN is the time to troubleshoot to see what the difficulty is. If all the cells measure the same in the garage sitting, you might have a cell failing with very high internal resistance. It measures good voltage sitting, but you put it under load and it can’t do that. Turn on your heater and check again. If still good, use the heater or some similar 10 amp drain on the pack to gradually bleed it down. Check all the voltages ever so often, and it should show up.

    Jack Rickard

  28. Tom and Jack !

    Most of what you say is true. BUT Tom when you say Lithium, making it sound as one cell chemistry it can really mislead people to think that your reasoning about BMS applies to all kinds of Lithium cell chemistries. I know that you(Tom) mention large prismatic cells in the same post so I do the assumption that you are referring to the CALB LiFePo4 or TS/Winston LFP/LYP cells. But for all other Li-chemestries there might be a need for BMS. As for the ferry fire: I also think that this was a BMS problem. But I would not charge that car without one anyway since it was not a LiFePo4 battery pack. I know, I know, your gonna say: just undercharge and everything is fine.
    Here are two different reason (other that old Lead acid habits sticking around) to why top balancing is commonly used as a BMS feature for Li-chemistries and has therefore also gotten to be used for LiFePo4(without any good use as you know). In other Li chemistries ie Cobalt based or Manganese based it is extremly important not to overcharge since it will lead to thermal runway and fire, so cell level voltage monitoring has been used to try to keep batteries from going over that safe voltage. Now for the two reasons:
    1. LiMn and LiCo chemistries does not have the same flat discharge curve as of the LiFePo4 and therefore in a quest of trying to maximize the amount of usable energy the cells are taken to there highest possible safe voltage at charge and get the higher voltage to give a higher energy.
    2. Ease of usage, if the pack is topbalanced while charging small adjustments in balancing can be done at every charge, and the need of circuits that can handle large amounts of energy (current) for shunting or shuffling can be minimized.

    I’m not saying that this should be done on LiFePo4, but rather stating that the thoughts on topbalancing might not just come from lead acid, but also from other Li chemistries.

    Jack, have you checked out that CANBus interface on the Elcon chargers yet ? It could turn them into really versatile chargers. Since they also do the dual voltage.

    Thanks for now, and Happy Holidays to you all !
    Best Regards
    /Per Eklund

  29. Per:

    I have not. As we see here, they could also be turned into bombs just as easily.

    I do not agree with your comments on top balancing and other chemistries. But as I have little direct experience with them, I’ll not comment beyond to say – extremely unlikely.

    Jack Rickard

  30. Fresh cells require fresh thinking.

    In my post, I explicitly state that I’m only talking about large format prismatic LiFePO4 (and their variant) cells from 3 manufactures, and yet more than half of the responses are about other Lithium-based cells and lead chemistry batteries. The discussion then goes to what someone knows about THOSE cells, and why its important to our understanding of the cells under consideration.

    That’s the biggest part of the problem with these batteries- guys think they are like the batteries they already know, and the their learning about the new cells is tortured around their hard-earned knowledge of something completely different. That leads to disappointments, ruined cells, and fires. Please stop talking and thinking about other cells, how these cells are the same and different, and what “must be” or “surely cannot be” because of what you already know for certain. That’s the opposite of science.

    There’s a more practical reason to get a good battery learning mindset in place, too. LiS chemistry batteries will be out soon, and I predict in the next 15 years we’ll see at least 3 more chemistries become available in EV batteries. Its irrational to expect them to behave just like LiFePO4 batteries in every important way. Each will need to be approached with the same open mind and careful method as Jack and others have done with the current batteries. In this frothy technology sea, the manufacturers will not do this for us, and they haven’t for any existing Li chemistry to date.

    Anyway, my point is that the more you indulge the comparative need to fit what you are learning about large format prismatic cells into your expertise with other chemistries, cells and formats, the more likely you are to miss something unique or really totally different about the new cells because your thinking is clouded.

    One also has to be rather willfully open-minded about new cell types that come in a very similar package to the old ones, and may indeed behave generally very similarly- except when they don’t.

    That’s the real challenge going forward- keeping your mind up with the facts…


  31. @Tom A:
    I’m really sorry, I see that now, it was the post by John that I had mixed up with your post. But I’m not arguing with you on the LiFePo4 cells. I think they will do just fine without cell level management. I know they will because I run them that way right now and they work in my car.

    But I was just adding an alternative source to where the ideas of top balancing has come from.

    Maybe thats all in vain.

    @Jack: I don’t think that the charger turned into a bomb, more like the Cells because of the BMS.

    BUT i’m not suggesting that you’re to use a BMS to control the Charger.
    I’m suggesting that you have a kind of “break out” charger controller to give you the flexibility to adjust the chargeprofile for different set-ups.

    On one hand your screaming for a good charger, and yet one of the best ones that you tested as far as accuracy in end voltage, does not interest you since it has to be shipped to china to be reconfigured. I’m giving you a hint on how it could be done.

    Anyway Jack, I love your show, and i would love to come over and have a chat with you f2f, but there’s the distance.. Gonna watch the new show now.


  32. Per:

    The electronics used to control the charger are LESS likely to be reliable than the charger itself. If they fail to turn OFF the charger, the batteries are overcharged. If they are overcharged, they melt and ultimately burst into flames. That then burns down the car and the building it is in.

    That’s a bomb.

    Jack Rickard

  33. Jack
    Points 1-4 are exactly how I feel. Point 3 is your bottom balancing solution. From what I have learned from you and other sources is to keep the charge discharge cycle on the linear portion of the curve. Or as you say: “don’t overcharge, don’t over discharge”. If I wanted to do this I assume I would need a smart charger, a smart controller and an accurate means of measuring SoC. And perhaps voltage deviation, but between a split pack, not individual cells.


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