BATTERY JUMP SHIFT

Of all the lithium chemistries available, we’ve found the LiFePo4 based lithium cells to offer the best combination of safety, stability, cycle life, power, and energy density. Though slightly less capable in terms of energy density per kilogram, the trade offs of much more stable and safe operation, and the very much longer life expectancy of these cells have made them a favorite.

Of the LiFePo4 cells, the A123 cells are often offered as the mark to beat. We have not found it so. We early on identified the Sky Energy large format prismatics in 100Ah and 180Ah sizes as much more convenient to build into an electric vehicle and offering a flatter discharge curve and long life when compared to all other cells on the market.

Sky Energy received a large investment from the China Aviation Missile Academy, a government entity, and became the China Aviation Lithium Battery Company (CALB). They continued production of the Sky Energy design as the SE series of cells which we have used successfully in a number of builds.

In June, 2012, CALB is introducing their new CA series of cell, notable by its newly designed grey case. Commonly referred to as the “grey cell” this introduction has been eagerly awaited since its announcement well over a year ago.

EVTV has developed a reputation for ruining the party at Lithium battery celebrations by actually performing direct first party testing on cells – often to destruction.

In this comparison, we do NOT perform any direct testing but provide a comparison of the SE and CA series cells based entirely on data provided by CALB, which we’ve found in the past to be quite reliable. Indeed, if we have a criticism, it is that CALB tends to hide their light under a bushel, seeming almost hesitant to make claims for their product.

In this fashion, they have very modestly provided us a spreadsheet of almost puzzling data that on further examination, would seem to hide a stunning advance in LiFePo4 cell quality. We are not at liberty to share the spreadsheet, but rather here present our best take on it, with excerpted graphics.

We do of course plan an entire series of episodes presenting EVTV test data to support or refute these claims. But if past experience holds true, we look forward to discovering performance quite beyond their claims, and we are genuinely excited to examine this new incremental advance in cell chemistry.

It should be noted that it is our intention to begin distribution of these cells through the EVTV online store at our web site. And so we may be viewed as something more than a disinterested party in the matter.

That said, note that we chose the battery, the battery didn’t chose us. Indeed, subsequent to our rejection of the head of their marketing groups desire to establish a U.S. marketing slogan – CALB – Cost A Less Bill, we have never successfully had a relationship with CALB for advertising or sponsorship at all. Indeed, our humorous response to this suggestion must have lost something in translation as he was pretty seriously offended by it. None intended of course.

Despite this, we’ve remained enthusiastic over their SE series and have sent many conversions their way. With the advent of this new CA series, and the ongoing difficulty our viewers have in finding reliable trusted sources to purchase lithium cells from generally, we have painfully arrived at the conclusion that we not only have to sell the batteries ourselves, but stock them in our facility at a somewhat enormous capital expense.

We intend that the immediate impact of these cells will simply be better cars, better conversions, and better results for our viewers. As they demonstrate these very desireable vehicles to their friends, neighbors, and relatives, we believe the demand for electric vehicles will be accelerated and the adoption of electric vehicles in America will within a few short years comprise over half of all vehicle sales.

In the short and the long of it, the story of DIY conversions in America since 2008 has been all about one thing – the enabling power of the batteries. We believe we enjoy SUPERIOR batteries to those used by Tesla, Nissan, and General Motors in every respect. These cells have allowed electric cars to cross the threshold of viability, moving DIY conversions from semi-interesting science projects, to actual drivable useable automobiles, in one smooth move.

The introduction of the CA series represents an incremental, but quite important advance in these cells, and consequently the cars that use them. They really do NOT offer any particular advance in energy density and thus range. But we believe they will provide greater power, longer life, more consistent capacities, better thermal characteristics, and much improved cold weather performance. This represents a kind of maturation of the chemistry, and we find these kinds of improvements really more important than range. Our cars go further than we do now. But longer life, better power output, less heat, better performance in cold weather are all extremely valuable characteristics at this point.

One feature we expect is not provided in the test data, but we intend to test it. Part of the process, and the delay, in introducing the new grey cells was some pretty serious behind the scenes advances in the scale of cell manufacture through the building of newer, larger, and more automated production lines for these cells, enabled by the financial backing received from the government.

This would appear at first glance to hold nothing for the end user/purchaser of the cells.

But one generally overlooked aspect to cell management is the fact that we don’t use cells in cars at all. We use STRINGS of cells in our cars. And our range, and our performance, and our power output can never exceed, to even the slightest degree, the abilities of the LEAST capable cell in the string. You can have 35 cells capable of 10,000 amps of power and a 1000 mile range. If you have one cell limited to 200 amps and 30 miles, your car will never travel more than 30 miles, nor accelerate at a rate greater than 200 amperes can deliver.

I would much rather have a string of cells rated at 180 Ah where each and every cell showed exactly 170Ah capacity, than to have a string where all the cells actually tested at 200Ah, except for two at 165Ah. A more consistent string is easier to charge and discharge safely and effectively and will provide better range and performance simply by being consistent.

So one of the less obvious aspects of the CA cell is CONSISTENCY – what do we actually get out of the box in terms of capacity from one cell to the next. And with these larger, more automated, more efficient assembly facilities, we would expect to see a more consistent product – leading to much improved cell strings in our cars. We intend to actually test this against a box of undisturbed SE cells we have on hand.

And now the bad news. At this point, the erosion in cell prices appears to have not only stopped, but reversed in some ways. CALB, now well financed, has been very stuck on pricing and we are seeing some firming in the other companies as well. Some second tier cells were going as low as $1 per Ah for a few months, but that appears to be over and if anything cell prices appear to be rising slightly.

While we don’t see this trend holding long term, in the immediate future we seem to have formed a “bumpy bottom” in LiFePo4 cell prices. We would love to see a dramatic decrease to half the price in the near future. But it appears to be wishful thinking at this point. In increasing capacity to meet demand, the expenses incurred appear to have put battery manufacturers in a kind of lithium vise. They face ever increasing over capacity and competition, with an inability to deliver cells at any price lower. And so we see their marketing efforts turn hopefully and expectantly to large purchasers for Wind farm and grid power applications. It remains to be seen if this works out for them, but the DIY EV market appears to not offer sufficient clout to drive discounting. We face more likely abandonment than price decline.

Again, we intend further direct testing in the future. But this should provide a peek at what is claimed for these cells on introduction.

HIGH RATE DISCHARGE PERFORMANCE

All LiFePo4 cells have a stated capacity usually in ampere-hours (AH). We currently carry the CA180FI and CA100FI cells that feature a stated capacity of 180 Ah and 100Ah respectively.

This amp hour rating is measured at a defined rate of discharge of 0.3C. The 100Ah cell would provide 100 ampere hours at a rate of 30 amps. The 180 Ah cell would provide 180 Ah at 54 amps.

At higher discharge rates, the capacity available is decreased. In the SE series of cells, you could expect at a discharge rate of 3C or 300 amps for the 100 amp cell, a capacity of 94% or 94Ah. In the CA series, this is much improved at 97.7% capacity at 3C. Your 100Ah cell will still have nearly 98 Ah at 3C compared to 0.3C.

The charts below compare the CA60FI and the SE60AH cells for high rate discharge performance.

THERMAL INCREASE

All LiFePo4 cells exhibit a rise in temperature when discharging. The internal process of intercalating lithium ions has certain inefficiencies that show up as heat. At low discharge rates this is of course minor but as the discharge rate increases, so does the heat gain.

At 3C, the SE cell series shows an increase in temperature of 22.6C.

This is actually pretty good. The cells have proven to need no particular cooling at all. They are quite hardy up to about 65C where one of the electrolytic solvents begins to deteriorate.

So at ambient temperatures of 30C for example, an increase of even $25C leaves us at the 55C level. And they cool rather quickly under lower discharge rates. So even under heavy acceleration, we’ve found cooling of these cells just not necessary. Indeed, they perform better up around 45-50C.

But thermal gain is a sign of an efficiency loss. For the CA series, this is dramatically decreased to a temperature increase of 8.6C. Internally, the CA series is just much more efficient than the SE series. And this points to even more durability and likely longer life under high accelerations and power demands.

POWER DENSITY

One of the more important factors in LiFePo4 cells is their ability to deliver power (current) on demand. We usually relate the number of amperes a cell can deliver with the corresponding decrease (sag) in voltage. More properly, this is measured as POWER DENSITY in Watts per kilogram at various levels of state of charge (SOC)

This chart compares the power density of the SE40AHA, the SE60AHA and the CA60FI cells.

At a 50% state of charge, the SE40AHA shows a power density of 890 W/kg while the SE60AHA shows 779 W/kg. The CA60FI shows 1322 W/kg – a 70% increase over the SE series.

We were able, for example, to discharge the SE180Ah cells 1000Amps with about a 22% voltage sag when testing the Speedster Redux with a Soliton1 controller. This would imply that the CA series cells could deliver 1700 amps in the same situation.

The spec sheets on the new CA series cells have thus far been spotty, conflicting, and incomplete. The SE cells we used to rate at 8C at EVTV. We would conservatively claim 12C on the CA series from this data, and we will attempt some sort of testing as soon as practicable. This is a little difficult on these large format cells. Even the 100 Ah cell would thn require a 1200 amp load to prove this.

COLD TEMPERATURE CAPACITY

One of the disadvantages of LiFePo4 cells compared to other lithium chemistries is a rather sorry performance in cold weather. While not nearly as debilitating as it was in the old lead acid battery era, the decrease in capacity of LiFePo4 cells is very much a factor.

At a temperature of -20C, and a discharge rate of 0.3C, the SE series of cells will provide 71.9% of capacity. Your 100Ah cell will provide a discouraging 72 amp-hours at that temperature. This is of course even worse at higher discharge rates.

The CA series cells provide a dramatic improvement in cold weather performance with 87.49 % of the original capacity. Your 100 Ah cell now provides a little better than 87 Ah at -20C or -4 degrees Fahrenheit at a 0.3C discharge rate.

CYCLE LIFE

One of the most important advantages of LiFePo4 cells compared to other lithium chemistries and certainly with Pb chemistry cells is their very long life. We measure this life in the number of expected charge/discharge cycles to 80% discharge and until the cell exhibits 80% of its original capacity..

This is projected by doing several hundred charge/discharge cycles at 1C and to 100% depth of discharge and extrapolating the data to the point where the cell exhibits 80% of its original capacity. This calculation is also improved by assuming an 80% depth of discharge instead of the tested 100%.

At 290 cycles to 100% at 1C, the SE series cells show about 85% of original capacity. The CA series has upped that to about 91%. This represents a huge increase in cycle life for the CA series cell.


Assuming that this had extrapolated to a 2000 cycle life at 80% DOD, the new cells would imply 3300 cycles. For 3000 cycles at 70% DOD, the CA cells should see 5000 cycles

The result appears to be a bit of a huge leap in battery performance at a very minimal increase in price. So while prices have not really come down, we’re getting more battery per ducat in a number of very interesting ways.

After a period of relatively static lack of movement in battery cells over the past year, we are enormously excited by this new introduction. After seeing this data, we are attempting to triple our investment in stock on hand on the assumption that these cells will be very much in demand for the foreseeable future.

We intend to ship all cells with our braided cell strap with Nordlock washers

Jack Rickard

http://EVTV.me

41 thoughts on “BATTERY JUMP SHIFT”

  1. I am truly sorry, but we are going to have to go back to moderated comments. Dan Friedricksen has gone off his meds again and is on a positive tear. He’s just become insufferable and I can more easily review and approve comments than I can deal with him on a 24 x7 basis.

    It is unfortunate that in every swimming pool there is one little kid with that Baby Roth floater. I have done everything I could to make this spoiled brat go away. I’m running out of ideas. We are probably going to WordPress soon with the blog just so I can eliminate him from our public discussions,.

    Again, please bear with us.

    Jack Rickard

  2. Thanks for the info on the new CALB’s Jack! Any plans to do any hot weather testing? The LEAF batteries are in the news this week for (allegedly) losing considerable capacity in very hot climates like Arizona. Most places don’t get 110F as often as Phoenix does – but many spots in the US hit that on occasion. Should we be worried about leaving our cars outside on very warm days?

    1. The Leaf uses a Lithium Manganese Spinel chemistry. Completely different animal. All these LiFePo4 cells thrive in the heat and in fact I’ve been getting phenomenal performance this week from the Speedster as it is 95F here now.

      That said, the thermal gain on the CA cells looks quite impressive. I don’t think they’ll have a problem even in Arizona.

      Jack Rickard

    2. Chris,

      From what I am reading some may be loosing some capacity but I am not so sure that it is an official claim. As you know the Leaf has a super great Guess O Meter. About as good at guessing as my anyone with no knowledge of SOC. My Leaf is still providing me the same distances a year later and 14,200 miles on the clock. I charge to 100% according to the meter which is actually not FULL. So I have no problem charging to full each time I drive back into the driveway from a drive even if it was for just 10 miles. I charge right after my drives and so far no noticeable differences. I am taking mine in for its health check up either this week or next. I park in the full sun of the summer and the car gets hot. It does get to 106 often when we reach triple digits. The car gets hotter than that but the batteries being in the chassis the battery box temp never got past the middle line for temps, which is well within the safe zone of the pack.

      I assume it is not an official claim but someone not reading the Guess O Meter very well. Even among the Leaf owners there is lots of miss information. That really sucks.

      Pete 🙂

  3. Much time is wasted on the web forums/blogs dealing with the negative aspects of personal assaults when members would rather learn new and interesting information. “The weight of emotional tension ranges from feelings to things…from more to less on the scale…talk to me of things, not feelings.

  4. Hey Jack,
    I applaud you on fooling the Engine Control Module on your Cadillac Escalade. I can not wait until you take it for a test run. Regarding the Manifold Pressure Circuit, could you see modifying the r.p.m. range so that 4.84 vdc is at 8000 r.p.m.
    Why you ask? Because 3-phase AC induction and Permanent Magnet DC motors can achieve their maximum horsepower @ 2 times the r.p.m. in comparison to a series wound DC motor.
    Maybe this is something you can sell through your on-line store??
    Regards,
    Mark Yormark

    1. We don’t have it all “fooled” yet. We have it idling and we can run it up in Park. I fear this thing is going to fight me every step of the way.

      We’re playing battery this week. Then I’m going to hook up the HP Tuners rig and see just what level of DTC storm we have brewing in there.

      jack Rickard

  5. Awesome. I want them. I was trying to decide between 100 Ah or 180 Ah Calb SE cells (with cell count to get me near 32 kWh for either). Scrap that. I want CA grey cells. You are so correct that reliable suppliers is a big deal. I feel like I’m rolling the dice every time I place an order. I will be checking your store often to see what you will be asking for them. Thank you for the valuable service you are providing to the community.

    1. You’re welcome Joey. Yes, since we started dabbling in components, I’ve been inundated with people explaining the trust issue in gory detail. I had no idea there was so much sleaze at play in this community. Apparently, everyone gets embarassed at being taken and so doesn’t mention it. Silence is complicit.

      I had five daughters. You couldn’t embarass me if you parked me in the street buck naked with my soap on a rope and a wash rag – even with my rubber duckey.

      So we’ve had kind of a silent killer in the EV industry – fear of fraud. As I’ve been taken a couple of times myself, once for $10K and a second time by the group purporting to fix it, I don’t know why I was so unaware.

      Oblivious. But yes, I’ve heard from about four dozen with exactly the same story – they don’t want to risk $20k on parts with vendors who may or may not ship.

      Duh….

      Jack Rickard

    2. What is amazing to me is the numbers of American Companies that are doing the fraud vs the others out of this country. Got screwed with my EVSE. I finally got it 9 months later and it failed within a week and never got a response back for a replacement. Trust is a HUGE deal. I would have loved to been one to provide parts but capitol is small and no one knows me and I’d hate to have supplies on hand that now one will buy because no one trusts who they don’t know.

      Yes Trust and Honesty is a HUGE deal.

      Thank you Jack and Brian for stepping up. I am glad I can now buy without fear. That is HUGE.

  6. Jack,
    A very nice treatise on the CALB SE vs CA cells. I waited for the new cells for many months but was forced to buy SE cells in April. Maybe the next conversion…

    Looking forward to EVTV style testing of the CA cells,

    Roger

    1. They appear to have little notches all around for some sort of wrench. But we received our cells today and I was relieved to find they are perfect matches for the SE cells with regards to the terminal bolt and strap dimensions. So our 70 mm strap kit works great on them.

      Jack Rickard

  7. Jack,
    With your acumen at researching and finding stuff on the Internet, is it possible for you to find a source for chrome vehicle badges that say “Electric”? I have been looking and so far I have not been able to find a source. It would really be “cool” if it was script. This might be a good product to carry in the store.

    I thoroughly enjoy your show and appreciate your’s and Brian’s efforts.

    Reagrds,
    Larry

    1. Larry:

      Found a company that would do them. A couple of grand up front, but we have wanted to do this actually.

      Now it’s a matter of coming up with a size and design.

      If anybody is any good at designing graphics?

      If not, I may go look up my old Magazine Graphics Goddess and see if she’ll do something.

      Jack Rickard

    2. Jack,

      I am not all that good with design, but I can machine the logo out of aluminum for a pattern (or make a Die Cast mold)….

      I have be working on a VW type logo for the Thing (Kind of like the Karmman Giha angled logo)

      Would be happy to help out if I can….

      P.S. I was a tool and die designer for several years in the injection mold industry…

    3. I am working on a logo for the VW thing. I want it to look like the old Angled Logo on the Karmma Giha…

      I am going to machine it out of Billet Aluminum. I can make a few extras if anyone is interested…. I will polish mine a clear coat it….

  8. We had quite a discussion today. Apparently we are the only ones stocking cells. Everyone else just has them drop shipped from Pomona. It looks on their web site like they hate them of course. And of course, if they are out of them in Pomona, delays.

    This is expensive. But it does open up an opportunity. We get a manifest with the batteries listing the capacities. I’m checking one now but it looks pretty close to what they put on the paper.

    This opens up the concept that if we went ahead and bought four or five hundred, we could basically do a select.

    I was disapponted to see they are no more consistent than the SE’s and delighted to see that UNLIKE A123, the 180Ah cells from CALB ranged from a low of 194 Ah to a high of 201 Ah.

    It would take a lot of work. But if we unpacked all crates, and matched up each cell by serial number with the manifest, we could conceivably tag each cell with the AH capacity.

    THAT leads to more work. We could conceivably line up the cells by capacity. In this way, we could do a 194 select, a 195 select, a 196 select, etc.

    It complicates things horribly in ordering. And I would actually have to hire a couple of people to make this happen. But the end result would be battery packs +/- 1 AH. As you only go as far as your least capacity cell anyway, most of the balancing headaches and reasons for BMS’s etc, kind of go away.

    The question is, how much extra would you pay for “select” cells.

    Right now we are priced at 252 per cell. I’m thinking something like:

    265 – 194 select
    270 – 195 select
    275 – 196 select
    280 – 197 select
    285 – 198 select
    290 – 199 select
    295 – 200 select
    300 – 201 select.

    We’d probably have to order in 1000 cells to make this work. That’s a quarter million dollars. And your car basically works with the run of the press mix. I can see huge advantages to doing selects, but then if 92% of our sales are “run of delivery”, having a quarter million in selects sitting here won’t do much good. So I really don’t know how to gage this.

    Jack Rickard

    1. If you take the AC-50 as a base line car…

      180Ahr Bulk Sales = $9,072, 200Ahr = $10,620

      so basically you spend $1,548 for 20 Ahr…

      I guess if I was always pushing my range, it would be well worth it, but if I rarely get below 20% on the pack, not so much….

      Sound like the same argument of the 150 mile range Tesla Model S vs the 265 range Model S. Most people DO NOT need the extra range, but most will buy the one with the max range for bragging rights.

      Bottom line, I would pay the extra to get the 200Ahr cells. Another way to look at this is that the Extra $1,548 is less than 1% of the cost of building the car….

      P.S. I ordered 36 cells yesterday so unless you have 36 matched cells in your 100 I guess I am out of luck….

  9. When I want to order 180ah cells, I expect 180ah cells. If they were selected as pictured, it would only give a 7ah difference, and as far as I’m concerned not worth hiring someone to match them, not to mention the extra costs.

    As for balancing headaches ….not sure about that. It comes down to who I want to pay to get a balance, me or you (or whomever you hire).

    Roy

  10. I think that instead of fixing the prices for “selects” you could set up an automatic auction system. It would solve the supply/demand disparity.
    And Internet is great for such things (look at eBay).
    Second option: selling the cells as they are but picking up the best ones – like 199+ and selling them for premium price.

  11. Sorry about my doubled post before. The first gave no indication of message sent.

    Jack I can almost feel your palpable excitement. I’m sure you know the odd trustworthy dealer/engineer with a bottom balancer who might like to come aboard with the workload.

    Pricing to capacity can lead to a minefield of mental juggling over that $7/3.5% as people decide on sizes/price. You could offer one higher price and refund down as good will depending what is delivered/available. The higher capacities will go first as soon as the numbers are made up so early orders!

    My mind mindlessly minding.

  12. You guys have kind of answered my question. You immediately go to longer range and capacity. The advantage of selects is that they are the SAME capacity, not that they are of a higher capacity.

    We would naturally price the higher capacity selects higher than the lower capacity, but the big jump is from random to select, not from 194 to 201.

    It would appear after three years of doing these videos that has not been adequantely communicated, largely because there was no way to do it anyway. But MOST of the problems people have with serial cell strings are the result of simply having different capacities in the first place.

    But I think you’ve probably saved me a quarter million dollars here. It’s much easier to deal with them by the crate than by the cell.

    Thanks.

    Jack Rickard

  13. Here is the breakdown of the first shipment of 100 cells:

    201 Ah 1
    200 Ah 3
    199 Ah 6
    198 Ah 23
    197 Ah 17
    196 Ah 24
    195 Ah 10
    194 Ah 8
    193 Ah 2

    To get a set of 36 2OO Ah cells would require an order of 1200 cells. That’s about $300,000 worth of cells to get one set of 36 200Ah cells.

    Then too, 67% of the cells are 196-198. That’s actually pretty consistent. That’s pretty good. But one 193 Ah cell pretty much defines your pack then.

    As you say, they are ALL over 180Ah. And indeed they will go UP in capacity for the first 50 charge cycles. Then they start to go down.

  14. As to the logo, this is easier than you guys are making it. I need a PHOTOSHOP design. They’ll do the 3D and chrome and all that. But it needs to be sized right, the right font, something really cool or I’m disinclined to spring for the tooling.

    Jack Rickard

  15. Maury Markowitz

    Can someone suggest a good reason why the battery industry continues to use Ah for capacity measurement? No one cares about how many Amp-hours it can deliver, all we want to know is Watt-hours. Right? Or am I wrong?

    Anyway, my real question… I’m trying to better understand the BMS’s role in stringing batteries in parallel and series. Jack notes above that a string is only as good as the worst battery, but isn’t the BMS supposed to prevent exactly that problem?

    As you might guess, I’m still noobish to the ways of BMSs, but I am quite technical otherwise, so if anyone has some reading material they might point me to, I would be forever grateful.

    1. You are limited to the lowest capacity cell in the pack. BMS or NOT. Top or Bottom balanced. It is the safer bet to bottom balance the cells. As you all know you really never drive with a full pack anyway. It is always going to be less than full once you hit the road. I much prefer to bottom balance and I know first had what happens with a pack that is not well balanced at the bottom. You WILL loose cells. Once well balanced you won’t. B(M)S free one day at a time. 🙂

  16. If I was going to pay extra for selected CALB cells it would be based upon a matched IR rather than capacity. I spent over two weeks balancing a set of 100 AH SE’s with a Powerlab8 and they all could do the capacity listed on the CALB tech sheet. How efficiently they did it was revealed in the IR. That IR spread was pretty small but noticeable to the touch in a temperature controlled room (72F). All the cells were in the room for the duration. They went into the car bottom balanced and were charged to 85%. Not even my multimeter can find a useful difference among them after 450 miles. They just work great and are a joy to drive.

  17. Anyone know of a connector I can purchase that will handle a solid 200 plus DC amps? The anderson connector gets too hot at 100 amps. It’s only rated for 50 amps. I am connecting a stationary battery pack to my vehicle that I will be using to charge my cars pack. I need something that can be unplugged yet be durable and able to handle a solid 200 DC amps or more.

      1. I thought for sure Jack would have commented on the LiAir, Prussian Blue, LiS presentations listed here. Lots of interesting information, along with some BS in some of the presentations, but it is pretty easy to weed through the BS/marketing stuff from the science.

  18. Pingback: Electric Car Conversion By Zelectric Motors: Why the VW Beetle? | EV News Report

Leave a Comment