Not much going on this week. We’ve been suffering component and supplier setbacks and it is a reminder of the environment we are unfortunately in.
The James Morrison EVCompnents case is devolving into a legal morass that has gone on for a year now. Forty three customers were bilked outright of their money – checks cashed but nothing shipped in a kind of bizarre bankruptcy fraud exit model designed by Mr. Morrison. In a world where Marthaa Stewart can do six months without being charged with a CRIME other than lying to the government (technically a Constitutional obligation actually) no one in Washington State has ANY interest in this case, including the judge in a filed lawsuit who has just continued the case for another couple of months.
But we’re having it here left and right. Our PAIR of 400 watt DC-DC converters from Chennic, which they market as an 800 watt converter, made it about a week and failed. We have piles of failed components, and often the reason they are failed is mostly Jack Rickard. So we submit very few warranty claims. In this case, they had only operated for aweek. It’s true we were operating at the top of their range voltage wise, but we WERE within the published specs, and they published them, we did not. They seem to agree, but want us to pay shipping for the replacements, which is actually more expensive than the devices in this case. You already know the details of DHL’s comical 12 day express delivery. DHL informs us the refund must be applied for from the shipper. They have decided it’s too much trouble and have declined to refund our delivery on the ORIGINAL DC-DC converter.
It just comes down to people selling things, and when they go wrong, they just don’t want to do what they said they would do BEFORE you bought and paid for it, after it’s actually happened,
What’s amazing is they just don’t even blink about it. The excuses are not even creative. It’s just they don’t want to do the expense and what are you going to do about it? It has become a WAY of business.
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We contracted with Jim Husted for two controllers and two 9-inch motors at $14,000. We changed our minds and at George Hamstra’s anxious urging, given the visibility of this project, asked to change this to 11 inch motors. WE supplied both motors at our cost. Revised pricing: $14,000. ?????
Oh well, Jim’s an artiste, and kind of a starving one at that. We had kind of fumbled around on what transmission and of course changed horses, so to speak, mid stream. He HAD had a shaft made, but not much beyond that at the time. So whatever.
But the six weeks became six months, not a near miss. And last week we were assured it was going on the truck the next day, and of course please send a check. We noted we would send a check when Fedex had the item and we had a tracking number. Whoops, did we say TOMORROW. Oh, we don’t have any brushes for it. So much for Jim’s vaunted testing. He had never run the motor. Had no brushes for it, and apparently had no intention to ship it.
Finally this week they were shipping it. The freight? $1750 or thereabouts. Seems like a lot as we shipped motors and transmissions and so forth for $600 or so before. But the final result IS heavy and comes in a box five feet long. But he was REALLY REALLY going to ship it now and to prove it, he sent me the bill of lading and copy of the check to fedex – $1350 or thereabouts – forgetting that he had just invoiced me $1750 for freight.
Busted. Instead of an apology, I heard a litany of all he had to go through to build this motor, the weather being bad, losing his cat, problems with the wife, and all he’s striven to DO for this community over the years. Nothing, not even an apology, over the $400 disparity But he DID want me to know it would be ok if I also split the cost of the brushes – which somehow, someway, in his mind, never was included in the $14,000 estimate, for two motors he didn’t provide – WE did.
The ability of the human mind to rationalize all arguments in favor of their own pocketbooks is just without limit.
We also heard from Dennis at Crystalite. No the motor is not ready, and that 3-6 month estimate was perhaps optimistic. He assured me that companies do that in the United States MILLIONS of times per year. Oh, and rather than cover the cost of the controller, his boss had decided that they were spending enough on the motors, and whatever we discussed in the beginning, they had “decided” that I should pay for the controlller.
One of the things we discussed early on was the controller. At one point I actually cancelled the entire concept because they wanted to use a Kelley controller. Now we have used Kelly controllers and throttle pedals and a few other things in the past. I would not say successfully. The controller on the original speedster more or less worked, but it did have heat issues. And we had a couple of the throttles fail outright – again Kelley simply ignored their own warranty and explained they weren’t going to do that because they didn’t know how the throttle was used.
But we’ve also had a number of reports from viewers who had worse experiences with Kelley than ours. And while some of them were clearly operator error (turning on the maintenance switch with the ignition on is one way to blow any controllers input caps) there were enough of them we had decided to avoid their products generally.
So Cyrstalite was going to do their own controller or had another one in mind and wanted us to do this wheel motor thing. I was absolutely clear there would BE no Kelley in the car. They agreed. Six months later, all that has fallen through and they just HAVE to use the Kelly controller. Oh, and I have to pay for it.
We have put off a project I already had some $20,000 in, specifically to accommodate THEIR insistence that we should do it with wheel motors that were not only unproven, but had never ever been built or attempted by them. A six month delay, and THEN they want to change the game in all respects. And they’re “shocked” that I dont’ want to play anymore. I’m very happy to have not funded the motor part of this fiasco.
I have no idea what we’re to do or when with the Smart ForTwo. Mercedes Benz has since replaced Penske group, which sold all of 5200 Smarts in the U.S. last year. Mercedes Dealers are going to represent Smart and the hopes for the vehicle are actually pinned on their Smart Electric. This is actually a great move and a great car. The Smart is a fascinating vehicle with the absolute worst internal combustion engine and transmission I’ve ever seen and examined in person. By replacing it with electric drive, it becomes a great car almost by accident. It doesn’t belong on a freeway at all. But for city driving and parking it is actually a design example.
So six months later, the electric Smart ForTwo project almost doesn’t even make sense. The manufacturer is going to do what we were doing, and indeed is actually delivering cars before we got started. Thanks Crystalite.
EV’s have actually developed into a bit of a hot topic over the past two years. And everyone wants a piece of the action. That makes us, and you, a target. And not everyone is in it for the love of the game. All emerging industries attract a share of opportunists and fast buck artists. And the business ethic of even established firms has just eroded over time and economic pressure where it’s basically ok to do whatever you want to do in dealing with customers.
Its not ok. And ironically, I’ve never heard of one actually succeeding. The irony is that bottom feeders never do leave the bottom. With NO success stories to point to, it always mystifies me why the concept attracts so MANY players. But here’s the real deal. You cannot grow a business to success on the “there’s a sucker born every minute”
school of business.
This is not so Jesus will love you. Veteran entreprenuers viscerally know that the realistic margins that can be achieved on the value add of any product, never quite covers the cost of new business. What this means is that to succeed and grow, ALL businesses, and there just arent’ any exceptions, have to have a flow of cash from residual returning customers. In fact, this is so ingrained that a signficant and indeed usually central element of valuing any business is a concept called “good will”. This is an accounting attempt to value the “momentum” of a business based on a loyal customer base who return time after time for new purchases without the high costs of advertising, marketing, etc. They already have your number. And they need another one. Their friend needs one too. After awhile, they really need to keep a couple on the shelves.
This is true of ALL businesses and often MORE true of those you wouldnt’ think so. Running a hotdog stand is just selling hotdogs to random passersby. Anyone who has ever run one though can tell you that it doesn’t work at all unless you are at the SAME place at the SAME time for your regular customers whom you quickly get to know and have something to say to or ask about EVERY time they show. The new business is almost a distraction. You need it, but it isn’t where your bread comes from.
EVTV is a good, though counterintuitive example. You would naturally assume that our mission is to get more viewers. Actually not. Our mission is to make about 6 billion viewers go away. Leaving us with a handful that are intensely interested in electric cars. Not people who think electric cars are cool. People who think about electric cars all the time. That’s a market. Every time someone watches one of our videos I’m out a quarter. If they watch once and go away, I’m not out that much. If they stay, they must like two hour videos about ultracpacitors and DC-DC converters and how to implement J1772 for $300 dollars instead of $5000. Since most of the six billion don’t know J1772 from Jay Leno, they have to be “fired” as customers.
As to advertisers, we are having a hard time getting industry players onboard, and actually attracting bizarre requests for general ads. We can’t advertise weight loss on EVTV no matter how heavy you guys really are. Why? We can’t do them sufficient value add to make them “stick” as an advertiser. We would have to have a constant flow of new ones. There’s no business there. We have to find products and companies that will actually benefit getting the message to THIS group of viewers. Otherwise, we are selling too hard all the time and the cost of hte new business will ALWAYS swamp the value we can add…
Unless.. .. we MIGHT be able to pad the freight a little…..
Oh, the show. An introduction to capacitors and we build an Ultracap aux battery to smooth the 12v system. We got the motor temperature switch hooked up to the Soliton1.
OH and the best part, not really stressed in the video because we hadn’t really tested it at the time…. We now have a FULL SWEEP fuel gage, this is a beautiful little lit fuel gage whose needle goes from about 5 clock position to about 7 clock position the long way around, tied to the Zeva2 AH counter. We can easily compare this with our EVision AH counter. It appears to be QUITE accurate, quite visual, and very familiar to those who have driven a car before. It is a little counterintuitive and non obvious as to how to set this up, but if you pursue it persistently, it works MARVELOUSLY. I know it seems ordinary. BUt it is a breakthrough to me.
Finally, we give you a peak at our new showroom. We now have three porsches, two gems, a Green minivan, and a 2009 Mini Cooper in electric drive. And we’re starting our Cadillac Escalade project. Both for reasons of cost, and as importantly for reasons of space, we just can’t keep acquiring electric cars indefinitely So we’re going to open a show room, kind of phyiscally modelled after Special Editions’s new show room we saw in Bremen Indiana. And we’re going to backdoor out our completed works to make room and funding for new ones. So I guess, in an odd way, we ARE in the electric car business. Since you all are builders, you probably wont’ find it of much interest regarding a car purchase, but you might like to stop by and try our NINCO FOUR LANE slot car track. We have two Speedsters, a Spyder, and two minis on it at the moment.
27 thoughts on “Buyer Beware”
I hear the pain. It’s a sad state of affairs when “good will” means nothing any longer in this country. I have had better luck with businesses overseas vs those in the US. I have noticed exactly what you stated long ago and getting worse. It’s no wonder the country is in dire straights. For most of us it is no wonder we balk at making such a large investment out of fear we the other end will just TAKE our money with no regard and run. Hell they may not even run. Must have gotten lost in the mail. Can’t do a damn thing about it. I really hate those that pad shipping costs to sneak some extra cash. The shipping fees are for the shipping companies not me. If I find a good priced and reliable shipping company I will be a return customer. Like you said, that is business. Provide good service, quality parts and a warranty and you will get repeat customers. Don’t steal money which you pointed out is pretty much the normal way to do business these days. Really sucks.
MG is running better now. Turned down the amp rating and all batteries are cool, balanced and giving good power for such a small pack. I am pleased.
Love the show room. Those babies look real nice. Can’t wait to see the final result.
It’s difficult having to wade through bullshit, it stinks, and that stink follows you around like, uhm, a bad smell.
Sorry for you troubles.
Damn Jack, why did you cut in The Charging of the Capacitor pack?
Guess I was lucky only being screwed 2500 out of my 15k build. But I did drive 670 miles to pick up my thunder sky batteries. After reading about ev components I was a bit gun shy ordering batteries online.
We certainly don’t say it enough…”Thank you”
Hear Hear Travis
The united states’ business model is predicated on two things: apparent growth in GDP predicated on complex financial products housed on Wall St and improving profit margin by cutting cost. Service is a cost, so screw the notions of morality and community that underpin the society in which these transactions take place.
Past: Customer is king.
Present: How little can we give Jack Rickard and still keep him as a customer? How much is just enough to string him along and comply with our model of business given his needs?
For evidence of said business model, see phone companies, banks and airlines and every other company trending towards a monopoly and thus badly in need of reset. Unlike electric cars, this model does not seem sustainable, but I do wonder when and if the modern consumer can or will revolt.
But, hey! My stocks are up today so life must be good, meaningful and fulfilling.
I will know go drink.
I apologize in advance for all the honest bellylaughs you gave me from your being taken advantage of. Seriously, I thought you made me laugh in your videos, but now your blogs too! You truly have a way with words.
The new showroom is a logical next step for EVTV. And thank you so much for the segment on ultracaps; I can’t wait for more on them on the Escalade. This has to be my second favorite video after the one with Wayne Alexander.
You might give Mark Gelbien at EnerTrac a call about the motors for the Smart.
I’ve always thought that the Crystalyte motors Dennis tried to sell you were in fact copies of the MHM602 or MHM603 motors that Mark did all the design, testing and development on as a customer of Crystalyte. He has these motors in stock, and I would bet Ducats to doughnuts all Crystalyte was planning to do for you was fit the motors they are making for Enertrac to an automotive hub/brake, and pass them off as a new design. Problem is, of course, that its a lot harder to make something work than it is to make something that somebody else made work, but I digress.
Anyway, I followed the development of this motor because its about the only thing in the motor envelope of my Moonray, and Mark has now got it switching from 4-turn to 2-turn, which drops the starting amps, and he thinks with cooling he could maybe double the power from 10kW to 20kW; 60kW peak. It makes a nifty package under 50lbs each, and it can also be siamesed like your Husted “Signature” motor for double the everything (including, no doubt, the heat.) It wouldn’t be a hub motor, but you could hang two (or four) of them in back and drive the axle shafts with them. Mark hasn’t had any real trouble with the Kelly controllers, but then his motors can’t take very much power.
Of course, this whole hub motor thing is probably better forgotten, (which puts you in very good company, as you know,) except that you should do the early Smart conversion because the cars are only getting cheaper while the drivetrains get even crappier, and its just such a good idea. Why don’t you try one of the 37kW BLDC Motor/controller combos Dave Kois has, or is that just a picture on an online order blank of a product, too?
I feel for you, man. At least in the Wild West, these hustlers and charlatans would catch a branding iron or the tail of a whip from time to time.
Being crooked today is so easy and without consequences that its become the MO of the sloppy businessman, who in the old days at least TRIED to do the right things, but now just doesn’t see the benefit. Only a couple of generations ago, that would have been unthinkable.
Anyway, don’t give up on the Smart. Its cool, and at $5/gal gas, it will sell like a shovel in a gold rush.
OMG Jim’s robbing you blind!! what a burgling barsted!! $14k for 2 controllers and a machining job to graft 2 motors together that you supplied???? Rebirth Auto have a good concept for joining 2 motors together……
It pisses me off that people can’t make an honest days wages anymore….have to screw you over!
Feels like living in EV Town in the Wild Wild West. Thank you Jack and Brian for being the closest thing to EV Sheriffs. Unfortunately part of this adventure has been like gambling with a loaded deck.
But when you do get lucky, it feels really good. Full torque at zero rpm, dopamine surging EV grin had me at hello. I intend to spend more $$$ over the years refining the performance of our project. I am convinced your efforts (and losses) will help make your viewer’s projects much better, while steering honest money to the more ethical EV component proprietors.
Here is my relatively unpolished effort at chronicling my project:
We decided on components actually before I discovered your blog, so we are using a BMS. I am also struggling to get advertised capacity on a K2 pack. Months later, we are not yet receiving expected warranty replacement on at least one bad cell that was never abused. We are still troubleshooting with K2, and how they intend to support their batteries remains to be seen.
Now for the good news, aside from capacity specs, the pack does perform well in our configuration and seems to handle at least mild, inadvertent abuse so far.
The Boxster weighs more than the Redux Speedster, but seems to have stronger acceleration. Wanna race? But please, just not any farther than my 40 mile range, or you will always win! I speculate the difference in component selection may be higher torque of the Warp 11 vs Warp 9, and a bit higher pack voltage resting at 210V. However, under heavy load the K2 pack sags to 150-160V and I am seeing around 800-900A output with a full pack. That does not seem to be better than what your new pack is producing. Regardless, it seems to be enough to make the car giddy up n go, probably 0-60 less than 7 sec, and in a presumably heavier car. I will weigh the car soon and maybe even take it to a dyno once we are convinced we have maximized performance. The adventure continues!
Well, the point I suppose I was digressing to make was not primarily “Oh woe, it sucks to be me.”
Actually, it’s pretty good to be me. I sold my last company for $38 million cash.
The point, without getting too much into a condescending lecture mode into an ether of viewers that may indeed be the choir I’m preaching to, is that there is a RIGHT way to run a business and a wrong one. And it isn’t about Jesus loving you or your dog thinking you are a good guy. It’s how you build a business that grows each year, isn’t a constant test in stress management to run, and eventually builds sufficient equity that you have something for your efforts.
And the point is, you have to have a growing base of “residual” income from rewards earned previously and yes, that means a trail of customers who wish you well, want to keep you around, and know how to place a reorder without a graduate refresher course.
Here’s how that happens. Be honest. And be fair. And put yourself in their shoes. Stuff goes wrong. YOUR vendors show up with stuff late. Semiconductors are kind of “semi” in complying with their data sheet. Freight companies screw up. Etc. etc. But you’re the one offering the prodduct And you and your customer are not ON an equal footing. THey are paying and you are providing. They pay easier when they don’t have to scrutinize every invoice to find what new improved way you’ve dreamed up to screw them this month.
And if you do have a problem making a date or encounter another unusual circumstance – fall on your sword and let them know what’s going on and be honest about it. Don’t make up some bullshit story any 8 year old can tell is just pure d bullshit.
And remember that it is YOUR problem. Endeavoring to somehow make ti your customers problem or somehow wheedle them into sharing your pain isn’t the answer. If you do so, you now have TWO problems. The original one, and a very unhappy customer who USED to trust you.
Again, these principles have nothing to do with the generalized “being honest” or making Abraham Lincoln proud of you. It’s about prospering in a world where the others are struggling just to survive. And I’m not guessing. I started a business with zero capital, no investors, no bank loans, no angels, and built it into a $15 million annual cash flow with no debt and a good margin. That’s WHY somebody would want to buy it.
So price a few mistakes in, because you’re going to make them and some rain is just going to fall on your parade.
I didn’t beat Jim HUsted up on price. I accepted his first quote. And really i signed on to his second one, with ME supplying the motors. I was the one that wanted to change the game. He is an absolute artiste and has the pathological attention to detail I wanted on this project. His price was his price.
No it’s the $400 I was upset about. It’s just a little pinch off the edge of the cake and he was cocksure I would never notice. A $400 markup on freight?
His story of course is that it was for crating and “handling” . Bullshit. He crates every motor and that’s already in there.
So he instantly converted a grateful adoring fan into a “never again” ex customer. For $400.
Don’t be digging around for quarters in the carpet when there are $60,000 contracts floating around at head level. This IS derived from the “cost containment” school of management which is precisely what happens when you let “by the hour” accountants and lawyers run things. They are by nature precluded from running a company at all anywhere except into the ground. They’re hired help. HIre them. Then help them. BUt don’t let them run a company, much less run a country.
And if your an aspiring entrepreneur, aspire to be a great one, and in large fashion. Don’t think small. Don’t act small. And don’t ever let up on the details. And you can’t make money by screwing the few customers you’ve got, on the theory that no one will notice. It is absurd.
We’re all going to wind up working for the Chinese if they don’t smarten up.
I checked your EValbum and your blog. Nicely done. Looks like a great conversion.
I have one K2 “green” battery pack and box of their individual cells. Haven’t tested them yet.
One of the advantages of a BMS is all the nice data you get. You could be our poster child for the disadvantages.
The K2 cells do not appear to be nearly as consistent in capacity as we have with the CALB or TS cells. Which makes the top balancing scenario much more comical. You are showing a high of 3.213 and a low of 0.723 on your pack at full discharge.
We would count 3.213 as about half discharged and 0.723 as remove and replace. The problem is of course that the stronger cells can still drive current when the weaker ones are zeroed out – this reverses the cells and there is no recovery. And unfortunately, when driving, this isn’t all at 35 amps, but at 350 amps so it happens very quickly.
When you top balance, it is true enough that they are all “balanced” – at the top. But that exacerbates the differences in AH capacity at the bottom – a ragged edge. And at signficant currents, this eats cells.
Before our redux, we actually rolled the Speedster to a full stop – nothing left at all. No BMS to protect it or shut us down. The cells were simply so discharged they would not move the car. But we didn’t lose a single cell. They had not been top balanced, and were really pretty well matched I think. We put a charger on it, and they all came up beautifully and we drove the car another month or so. We’re actually going to use the cells in ANOTHER car project, after they had 2 years and 5000 miles on them in the first.
The only remedy for top balance is bottom balance, and I’m not sure how you would even accomplish that with your blade format. You have a beautiful car, and it is indeed a task to find places for our large prismatics, but you will simply have a much better car with an 80 mile range and none of these problems.
Again, top balancing is simply a blazing waving flag from a BMS designer trying to tell the world that he does not understand LiFePo4 cell chemistry. IF you feel you must balance, it should be done at the end of the discharge curve. And the concept of cell “drift” as a reason to balance simply has no demonstrable reality component. It appears to be a myth fostered by experience with older cell chemistries. We cannot measure it with all conceivable test equipment.
As far as I can tell, even though that cell went very low, 0.7V, miraculously it hasn’t weakened the capacity of the pack. I think it was a weak cell to begin with. So far it appears K2 cells have widely inconsistent capacities or are not amenible to our blade configuration for reaching overall rated capacity. However K2 chose the cells for our project, and welded these blades for us. The capacity seems to be gradually improving with deep discharges, and I think we are hoping they “wake up” as if they were in a long slumber in storage for two years. But months later, the biggest gain occured after replacing the weakest blade with our only backup, and we are still getting 20% less than advertised capacity overall.
Unfortunately, it may take a religious experience to convince my team to give up the BMS and bottom balance. I just hope its not my funeral with my car burning down my house. We are kinda stuck for now since K2 said they won’t warranty the cells without a BMS. So I will comply until they definitively tell me they will not replace the bad or weak blades in the pack if we fail to reach closer to advertised capacity.
If this doesn’t work out with K2, once this pack goes down below a 30 mile range I may make the switch to prismatics and bottom balance. I would like to keep the BMS as a monitoring system because I really like the data. It isn’t much more than monitoring right now anyway, since the software has not been written yet that turns off the charger once at top of charge. I am doing it manually. One of these days I will make a demo video showing the design and performance of the car for your viewers. Thanks for your advice!
Another great video. I have been waiting for you talk about the Ultracaps for a while and you made it crystal clear.
Love the show room! It gives you a better environment for taking pictures also. Very nice updated pics on EVAlbum.
While they may be slightly inconsistent, the irony of course is the BMS is probably what is causing the problems. If they require it, it will lead to early death for these cells as you have too large a disparity at the bottom end.
I have done many tests, and shared the data. That’s all I can do. Beyond that, it is truly buyer beware.
Without being a battery chemist or electrical engineer, the facts you have presented make the stronger arguments. I will talk to the team, and ultimately it is my investment and my decision. I don’t see more than an afternoon of work to drive the pack close to end of discharge and then burn off the larger capacity cells thus acheiving bottom balance. Once balanced, I can monitor the voltages with the BMS, turn off or raise the shunts voltages to maximum average voltage limits, and set the charger to a slightly lower voltage trim. The manzanita seems pretty good at turning itself off once it reaches the set maximum average voltage. And the Zilla already demonstrated its ability to shut off current at end of average discharge voltage which saved me from catastrophe.
The specs on the K2 are nominal 2.5V to 3.6V and maximum limits are 2.0V to 4.1V. What would you suggest I target for bottom balancing purposes, 2V or 2.5V or somewhere in between? I need a small manual device that I can use to gently discharge higher capacity cells while monitoring the voltages with the BMS or my hand meter. Any suggestions?
One last question: Is there any harm to cells when voltage sag under load goes below maximum spec resting voltage limits. When I overdischarged the other day, I presented the data after about 30min rest, but I know that at least some of the cells went far under 2.0V under load. Two of the blades went so low the BMS circuit boards rebooted (blades 5 and 27). However, after 30min rest, those blades went back above 2.45V without reversing or obviously damaging the blades. So, should I read the maximum specs as resting voltage limits, or maximum limits under load?
I just had an epiphany of sorts. I don’t need a device to gradually discharge the cells to a bottom balance. I already have a very expensive one: THE BMS. I can just set the BMS to 2.5V or 2.0V or whatever, and it will gradually discharge the whole pack to that level. Once happy, I reprogram the shunts back to a maximum overcharge limit. I don’t even have to drive the car anywhere. I can turn off the breaker switches to protect from DC/DC draw. Should be easy. The only other issue is setting the Manzanita to shut off the charger once I reach a good average top of charge voltage.
Well yes and no. You could do that with your BMS. IF you do, I would urge you to be in the room with it while doing it. These circuits are designed to shunt small amounts of current, and the problem is that semiconductor components tend to fail shorted and there is a bit of a hazard from the BMS catching fire. I would not do it this way if it were me.
However, if you first drove the car to a low value, it might well work that way.
I generally find it easier to bring cells up than drain them down. So we drive the car until we have most of the cells at about 2.75 volts. Then, any below 2.75 we bring UP to 2.75 with a charger. I have some cable clamps on a connector for it. So we just hook it up to a single cell or several adjacent low ones, and give it a shot for about 30 seconds or a minute to bring it up to 2.80 or 2.85. When we disconnect, it will settle to somethinbg around 2.75.
The knee of the curve is just below 3.00v. We want to be on the rapidly changing vertical wall of that discharge curve and 2.75 is a handy and safe point.
As to sag voltages, they are essentially meaningless beyond giving you an indication of cell internal resistance and maximum power capacity. The cutoff voltage provided by the manufacturer is AT the standard discharge rate, usually 0.3C or 0.5C. It will be ENTIRELY different at any other current and specifically what it will be is a function of three things:
1. Current draw (load).
So you will experience greater sag the more discharged you are, the colder you are, or the higher the current.
Likewise, with NO draw, you are tapped out at a higher voltage.
I consider the pack pretty much discharged with 2.9v x number of cells with little or no current draw – like stopped at a stoplight and maybe the car radio is the only draw or a turn signal. So if I have 36 cells, and I’m at 104 volts, it’s over. And from there to dead empty is a mile, maybe two at most – at 25 mph.
And that’s the problem with voltage. It will kind of be STUCK at 111 volts for 36 cells, 3.1 per cell, for quite some distance. Suddenly it plummets to 108 and then almost immediately 104. This is why we use AH counters as our primary SOC indicator.
But to do THAT you have to have a pretty good handle on your capacity. And it sounds like with the K2’s, you really don’t know.
I have to tell you that for what you have in those “blades” and BMS, you could have had enough prismatics for 130 mile range. I don’t know that you could easily fit them into the car, but you certainly could have bought them. And at this point, we consider them more or less bulletproof.
Hope it helps.
Very helpful. I drove the car this morning to discharge the pack before bottom balancing. I went about 35miles before the weakest blade 42 reached 2.7v at 65.1Ah. That is also the blade that went to 0.7v when I overdischarged last Sat. So, I damaged an already weak blade as you suspected.
I turned off the string containing blade 42 and went on about 5-6 more miles. I can extrapolate the additional capacity running only the rear strings to the whole pack. 10.1Ah were safely present after shutting down the front string. If I assume an additional 5Ah if we replace 42, that is 15Ah. Add that to the capacity before shutting down the front pack and we have 80Ah). The best I got before the deep discharge last Sat was about 72 (79Ah if I shut down the front pack).
So now that the pack is reasonably discharged, I reset the shunts on the BMS to 2.75v and so far no fireworks. Since so many of the cells have a much larger capacity, it may take a long time. The shunts burn about 0.5Ah. So this will be another way to see which cells are weakest. Glad I can work from home today!
One thing to consider with bottom balancing. If your cells vary in capacity enough then when charging the smaller ones will fill up first and the Manzanita may not notice the voltage rise on those cells and keep charging. You’ll have to watch carefully at first and set the end of charge voltage low enough to catch when your smallest cells approach full. If you have some damaged cells with reduced capacity you may have a difficult time getting the charger to shut off. I’m not sure the Manzanita will notice a 0.5 volt increase across the pack when one cell starts to go from say 3.5 to 4.0 V if the rest of the pack is still at 3.40V.
Jack could you discuss replacing a bad battery in a string. What do you have to do for the new battery? Does it have to be “matched” to the old batteries? A new one would have very different performance than the old ones. Would that cause a problem?
If it had to be matched that would pose a problem for maintenance.
As I’ve said a number of times, the cells come reasonably well matched from the factory. We neither top nor bottom balance. IF we have difficulties we bottom balance.
But occasionally, we do have to replace cells. This has come almost entirely from overlooking parasitic long term loads of a very low drain – usually from test instruments and other well intended strategies to prove we don’t need a BMS. Ironic.
We DO have a current GEM project that stems from it just being left to sit for 7 months with nobody looking at it and with the battery still connected. It drained the whole pack to zero, albeit quite gently and it looks like we’ll lose a couple there.
To replace a cell, drain it to 2.75 volts using a load or 0.25 ohm 50 watt resistor. When you remove the load, it will bounce back slightly but keep after it until it is stable at 2.75 volts.
Next you do your car the same way. I like to do this by driving it until all cells are below 3 volts, and then using the PTC heater or water heater to gently drain it down where the cells are grouped around 2.75 volts.
Strap in your new cell, and then thoroughly charge the pack. I always measure the voltage of the new cell right AT THE END OF THE CHARGE SEQUENCE to make sure it isn’t going too high. Usually, as a nwer cell, it iwll be low compared to the others at that point.
Good point. I am almost bottom balanced after about 36hrs. The BMS is set to text me when any cell reaches greater than 3.6V, and then I will try to set the Manzanita. If it doesn’t work out with the trim, I will need to charge manually until I get replacement blades for the really weak ones. I may decide to just take a blade out of each string rather than spend more for replacement blades. They are about $350 a piece for what amounts to a 13v 25Ah battery.
Rob the other danger is some BMS boards quit working at low voltage, but will continue to draw some current, potentially killing a cell. You should watch the pack like a hawk if you are going to bottom balance with a BMS, manually checking cell voltages constantly.
Jack, your way of how to make friends and influence people has not gone over big here in the NW. I find it all very comical. Many EE’s that don’t watch your show say you have got the BMS thing wrong. I tell them you only know that a BMS is not necessary with the battery chemistry you are familiar with which is the Winston and CALIB battery Lipo4’s. Correct me if I am wrong on this. Kokam, A123,Saft and others you have not studied long enough but what you have studied of A123 you did not like. Not to mention many batteries are not made available to you to study and there is only so much time in a day.
You refer to a gentleman, that posted 30 times in the Thundersky forum, to a past video but I noticed I can no longer view “Alex Smith battery horror” and many other shows that are further in the past that I need to review. Do you sell DVD’s yet of past shows? I need them. Bubba has conversed with you. He lives close, he told you he would be willing to pay for a “premium sight”. I better send you some money as I have cost you many quarters by watching your shows over and over again. Bubba and I are going to build a street drag car similar to the Whitezombie. On the side of it will be “This car powered by Jack Rickard BMS” Of course the only version of BMS will be your version of the Lee Hart Batt. Bridge. This will not make me popular during the Wayland Invitational I would not contemplate building a EV without your shows. Bubba’s going to help with the engineering and he already contributed 500 dollars towards a glider, I have my eye on a 1959 Anglia built by Ford for England with Bubba’s money I will only have 2500 dollars into the glider. It has a new purple or plum paint job. Thanks for all the testing and info, my build will copy parts of the Wayland and Rickard builds. Bubba and I won’t be able to catch Wayland now with his new Kokam pack but Bubba thinks we might do something with ultra caps. Thanks again for everything and please advise what is the best way for me to get all your past shows. Ray. Current EV here. http://www.evalbum.com/1892
Hey Wayland’s on the same page now that he got his Kokam’s