Tonight Is The Night: A Deep Dive into Energy Storage

Lithium Batteries are inherently humbling. The energy storage component of our electric vehicles is THE central issue to successful builds, so it comes as no surprise that we get a lot of questions about batteries. And every time I try to answer one, I think to myself "I hope that is more or less correct."

You see, I'm not exactly sure. And it may well be that I don't know.

This is a bit hard to admit in a world so replete with so very many online battery experts who are so absolutely certain regarding their beliefs regarding the cells, connections, battery management systems and so forth. I often ask myself "how did they get SO smart, while I struggle along trying to understand these cells."

There are two complicating factors. First, nobody, and by that I mean no humanoids currently in context on terra firma, actually KNOWS how these cells work. There are some hypothesis that are working along pretty well. And some theories that are more of the "working" version. But the people who INVENTED them don't really know precisely what is going on inside the battery. It's kind of alchemy. If we use THIS material here, and THIS material here, and add this magic lotion in the middle, we can measure THIS. Which is a good thing.

Along the way, we can actually IMPROVE the battery without really knowing much about it. If we add THIS magic sauce to the cathode, it does nothing. But if we add THIS OTHER magic sauce, it improves things. If we use THIS magic lotion electrolyte, we get THIS and if we use this OTHER magic lotion electrolyte, we get THAT.

And there are basically four things they seek to improve:

1. Energy density - how much total power can be stored in a given volume (volumetric density) or weight (gravimetric density).

2. Power density - how much instantaneous current (power) can this battery deliver into a load.

3. Cycle life - how many times can we discharge and recharge this cell.

4. Safety - how soon before it burns our car and house to the ground.

We have some measurable indications of things like the formation of the Solid Electrolyte Interphase (SEI) layer on the anode. We can take a used cell apart and actually see it. How it forms is a bit of a mystery. What it does is a matter of controversy. It's an advantage in one sense, and a huge disadvantage in another.

The second complicating factor is that a thing can be VERY true about these cells, and that can matter a great deal, somewhat, or not at all. And this is all about context. Compared to what? And for practical purposes, does it matter?

For example, do Lithium ionic cells self discharge.

Lead acid cells readily self discharge. An internal shuttle mechanism causes the battery to discharge with both terminals connected to nothing. No load whatsoever. The internal discharge rate is a function of the equivalent series resistance (ESR) exhibited by the cell. And so each cell in a lead acid battery self discharges at a different rate. This is what leads us to the concept of cell equalization and the necessity for having it. This is so ingrained in the battery "expert" community that they simply cannot mentally grasp a battery world where it is not so.

With regards to lithium cells, do THEY self discharge. The answer is I don't know. But if they do I don't care. Why? Well, in the first place, there is no similar internal shuttle mechanism to explain it THAT WE KNOW OF. Second, in this week's episode, the measurements IF we accept the values provided by the manufacturer, and IF we assume that both their equipment and our equipment are identically calibrated, which is a near enough sure bet NOT, then it would appear they do self discharge. About 6 millivolts over a 31 month period or 0.19 millivolts (0.00019 volts) per YEAR.

In BRAND NEW fully charged lead acid cells you can easily see 2 volts PER MONTH in truly excellent cells and I've owned batteries that fully discharged to zero in 45 days.

In that context, if you get the question "do Lithium ion cells self discharge" what is the correct answer? As a practical matter it is absurd. No, they do not self discharge. As a technical matter, PERHAPS they do. But we are talking about 0.19 millivolts per year. What action would be effective to counteract this? Why would we want to? It just isn't a factor.

Examine the three specification sheets on this page. Note that NONE of them list a self discharge rate. I can tell you that two years ago ALL of them DID. They listed it as "less than 3% per month". Do you know how they derived that data? I don't. But I made mirth of the fact that Chinese battery suppliers were trying to comply with American battery buyers demand that they indicate the self discharge rate on their spec sheets and so in a spirit of accommodation, they did. They copied the best self discharge rate they could find on existing battery specs which were of course lead cells. And sported it proudly on their spec sheet.

Of course it IS "less than" 3% per month and so it was absolutely, demonstrably, and empirically true. I mentioned this a couple of times in our videos and magically the self discharge spec disappeared from almost all Chinese lithium battery specifications. It would be heroically immodest of me, and astounding to you, to learn how much the information coming from Chinese manufacturers about their batteries has changed in the last four years, and from whence it came.

Which rather increases the pressure to "be right" on our battery information. But given that nobody really knows, and indeed it may not matter, that's kind of hard to do. And I question it constantly.

This past week I prayed to the battery gods and did my penance - standing for hours and hours in the battery lab, carefully measuring and remeasuring. And it is humbling to admit at the end of it that I don't know.

The topic that comes up is Calendar fade. Do the cells actually lose capacity over time. It is a given that they do. I've long maintained that they do not. We've pulled up cells from a 2008 Thundersky purchase every six months for four years, noting that the open circuit voltage (OCV) is identical each time.

But that's not really a capacity test. Voltage does INDEED indicate state of charge. But it does not indicate capacity.

And that brings us to the technology merry go round. I had an e-mail from a viewer very happy with his original Ford Ranger factory electric truck. But he was down to about 30 mile range on the truck and wanted to upgrade to lithium batteries from the long suffering Nickle Metal Hydride cells that had been in the vehicle. He didn't know whether to spring for obsolete SE100AHA cells or wait 18 months for obsolete CA100FI cells. He had already determined the merry go round time cycle, and just wanted to be on the ass end of it so the cells would be the least expensive.

The answer is you get on when you need to. There will always be two generation old cells available, the last generation still available, a good generation just coming out and the really GREAT battery is of course on the horizon. This will not cease in lithium batteries during my remaining life expectancy.

We have been having the conversation with CALB about how to dispose of a quantity of remaining SE cells while introducing some vastly superior new CAM series cells.

Your unceasing demonstration of thrift to the point of beggary, most recently demonstrated powerfully by the shocking flight of Better Place battery packs off my concrete floor, persuades me we could probably dispose of these somewhat gracefully IF the price was right.

And so began the strangest negotiation I've ever heard of. Between two honest men, who are so rare in today's world of commerce that they almost never encounter each other so this doesn't come up very much.

The one seeks the HIGHEST price he can get for the cells, but feels obligated to disclose that these batteries are really no good at all for any purpose. The other, seeking the LOWEST possible price to purchase, but reassuring the seller that there is nothing wrong with the cells at all and they are as good as the day they were manufactured. How to resolve this at all? It is actually too bizarre to contemplate.

But we agreed to test the cells carefully and let the hammer fall where it fell. As it turns out, and predictably enough, somewhere in between.

We tested the cells in the blind. And then we obtained the factory measurements on the SAME cells by serial number. The results were surprising to me. I have no difficulty admitting I was wrong. They are NOT as good as the day they left the factory. But they are good enough I don't think it matters at all. And pretty much I mean AT ALL.

We charged and discharged the three cells several times and at several different rates. One of the rates was C/3 which is why the testing was so boringly gruesome. That means a full 3 hours to charge, and 3 hours to discharge. In the end, the WORST case cell was measured at a discharge capacity of 103.298 Ampere hours. Two others were only slightly better up to about 105 amphours.

The factory data indicated the shipping voltage and the measured capacity at 111 amp hours. And data from the rest of the cells indicate a more common 103-105 Ampere hour initial capacity.

And so it would appear that calendar fade is real with these cells loosing just under 7% of their original capacity over 31 months or about 0.22% per month and a little over 2% per year.

The proviso is that the test site, the test equipment, and most likely the test procedure were all different. This COULD cause the apparent calendar fade itself. But my best sense is that those variables would account for 1%, not 6.75% difference. I've been fondling these kind of cells a long time. I don't think there's a 6% error in here.

Typing myself smart, and not indicated in the episode, is that my sense is also that this type of calendar fade is nonlinear. That is, it doesn't really fade at 0.22% per month, but more likely 3% the first month, and 1% the second year, and 0.5% every year after that. But that is a guess, no data supporting it at this point.

In any event, I would posit it doesn't much matter. The 103 Ah cells are probably going to come in at 96-97 AH. The 103Ah measured in the test is 3% ABOVE the advertised spec. And so as a value proposition, I still claim there is no such thing as calendar fade and these cells are perfectly good for EV applications.

Indeed, our Escalade, Mini Cooper, Speedster, and Spyder all run on cells of this chemistry today, and indeed cells that are OLDER by calendar than these cells are, which were manufactured on September 21, 2011.

We have also arrived at a price point that is much higher than I would have liked, and much lower than he would have liked. It remains to be seen whether or not you like it. But for a limited time, until the quantity runs out, we are making them available at $0.95 cents per ampere hour or $95 per cell, however you like to look at it. Your sense of urgency is advised by your sense of the lust of your peers for the cells AT that price.

A 36 cell pack for an HPEVS AC50 system then would run $3420. It would be a 12kWh pack which is not going to get you very far - perhaps 48 miles in most small vehicles where the AC50 would be appropriate. But that is further than you would go with 750 lbs of lead acid cells at $2500 which would likely last 2 years. Better, it would weigh 252 lbs. You could of course run two parallel strings of these for 90+ miles and 504 lbs of batteries.

Are they as good as the CA series. Not. That's next generation. And indeed, the CA series are simply not what the new CAM series is going to be which we should have in hand in early May - at a much higher price than either the CA or SE series. You still get what you pay for in lithium batteries. And where you belong on the lithium ionic battery technology merry go round is entirely up to you. I see some magic boat builds in my future using very physically small CAM cells with AC drive systems at 330volts or more. Speedster lite would undoubtedly have to use those as well.

The VW DOKA pickup will get a Better Place pack. Not actually my choice at all in chemistry, but the mechanics and packaging of these cells have grown on me immeasurably. We don't need great range or life with the DOKA. It is destined to be a local delivery and errand vehicle for us. And those modules should slide right into the treasure chest with very little fabrication. Some slides. Maybe some boxes. Maybe no boxes.

I am including some brand new fresh ink Specification sheets for the new CAM72F and CAM80F cells we will be carrying, and a sheet on the SE100AHA cells as well for your consideration.

We also had an occurrence that would be comical but it caused such an inundation from our viewers noting that there were Nissan Leaf battery packs - brand new ones - available from a Nissan Leaf parts warehouse online at $4100 and indeed one set for less than $2000. I found it curious of our position in that out of about 12 of these e-mail messages, not a SINGLE ONE had actually ordered and received a pack, they just wanted us to know about it. For what? Well of course they wanted US to once again determine whether this was unobtainium, a scam, or whatever before they actually entered an order. I don't know whether to be offended by this or flattered. But in any event, we did get online and ordered an entire battery pack and they did indeed charge our credit card the $4300 indicated with shipping.

My first inkling that things were off was when I received a tracking number and FEDEX listed the shipment at 143 pounds. That would be great news if a full Nissan Leaf battery pack WAS 143 pounds and I would put it in the same category as a full Nissan Leaf battery pack being available at $4100.

What we did receive was even MORE surprising. In a powerfully striking demonstration of corporate ineptitude, Peoria Nissan of Phoenix, claiming to be the largest Nissan Leaf dealership in the world, sent us a Nissan Leaf traction motor. Indeed these DO appear to be available brand new at about the same price - $4100.

As to the batteries, when we telephoned the online sales manager at Peoria Nissan, he told us he wasn't quite sure what happened. But they had no Leaf batteries in stock and probably never would. Indeed he relates that they had a customer with an ailing pack who brought the car in. Nissan sent in a team of engineers and technicians and actually demanded that all Peoria Nissan personel vacate the room before they would remove the pack and open it. They were not even allowed to SEE inside the pack. So he said it was unlikely they would ever be able to sell modules or packs. He didnt really know why or how it got up on the website other than they were putting the entire catalog up there and would have to work these things out over time.

In any event, they agreed to provide a will call tag to pickup the motor and issue a refund. That was last Thursday. Of course they have done neither as of MOnday morning.

Ironically, ultimately I see a day, after the cross-eyed myopic clench of proprietary paranoia releases its grip, when you will of course be able to order any part for any electric car online and from the authorized dealers. But it may be awhile. Meantime, there are plenty of wrecked leaf's available online for bottom feeders and dumpster divers to paw through for parts - yes even batteries. We may bid on a few ourselves. Given what I know of AC motors, it would be unlikely I would spring for a new Nissan motor in favor of one out of a wreck with 2500 miles on it.

In fact I think this will be a cornucopia of future parts. It would be unlikely to have a car with a front end collision that did not have some serious motor damage, at least to some of the ancilliary parts. It would be also exceedingly unlikely to get a Nissan Leaf in ANY kind of collision not involving fire or flood that DID put as much as a scratch on the electric motor. I just can't imagine what you'd have to do to damage one beyond fire or flood. Similarly the inverter, the charger, and the DC-DC converter.

I have had another epiphany you might find interesting. I've had two people from Cape Girardeau who have moved to other cities in the U.S. Both report that on their first conversation with anyone in the new town, when they advised them they were from Cape Girardeau the locals responded - "oh yes. That's where Jack Rickard is from." Flattering in that that used to be Rush Limbaugh's position.

But I couple it with the startling realization that after 3 months, we have but 86 custom electric vehicles listed in the database. Now its true that it is a bit of a gruesome process, and no I haven't myself gotten around to entering the THING or the Escalade or the MiniCooper. So there is some latency. But it would appear from these two bits of information that we have an almost global and universal dispersal footprint, into a community so small that when you let the air out of the electric bicycles, motorcyles, lawn mowers, and the odd divan, the community of people who have actually successfully built a custom lithium ion powered car is very very small - indeed select. You guys are not a minority. You are a total outlier that statistically does not exist.

As this May marks five years that I have devoted nearly every waking moment to doing a weekly video for such a small group why am I so happy?

It kind of reminds me of the story of the guy giving a seminar on marital relationships to ask everyone in the audience who had had sex with their spouse to stand. He then asked those who had sex more than three times a day to sit down. A few couples sat down promptly and of course began eyeing each other. He then asked those who had sex at least once per day to sit down. A few more couples did.

He then asked those couples who had sex once per week or more to sit down. The vast majority of those standing took the dive on that one. He then followed with those who had sex at least once every two weeks to sit down and most of those standing sat down. He then asked for those who had sex once per month or more frequently to sit down and almost all the rest sat down.

He then asked for those who had sex at least once every six months to sit down. This left one couple still standing and the husband was waving his hands wildly and grinning. How often? the presenter asked. "Once per year" the guy shouted out exuberantly.

"Well you certainly seem happy about it for some reason. Why are you so excited to be here having sex but once per year?"

"Well," the guy looked down shyly. "You see TONIGHT IS THE NIGHT!"

I spend several hours each morning dealing with 150 e-mails daily. We have numerous viewers claiming to have watched every single episode. And we are now the largest purveyor of EV components in the world. It LOOKS from our webstat analysis tools as if we have between 22,000 and 25,000 viewers worldwide who essentially download the video at least twice per month. And I regularly hear from viewers I know have excellent results such as Dale Friedhoff in St. Louis and Ed Pezant in Louisiana that report it is one of the most satisfying projects or things they have every done. And have essentially become local celebrities because they did it.

Now how is this going to turn out? What do you imagine it would look like to ME if this thing actually caught on and a couple of HUNDRED people worldwide started building these cars, instead of just 86? Or dare we imagine? 1000? I would have to have 10 people answering e-mail for me and Amazon's bandwidth would not likely be able to handle all the video downloads.

And as better drive train components become available less expensively, and most notably batteries, maybe....just maybe.... TONIGHT IS THE NIGHT!

On the other hand, one camel sneeze and the world goes to shit in front of us, with a mad scramble for electric cars.... that would actually be unpleasant.

Jack Rickard