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I happen to have a set of these on order. From everything I could dig up, the 4C rating is correct.

Most EV designs that I have looked at tend to size the pack for 1C constant discharge without issues. No one really knows the true life of the pack at a given C discharge. I looked at AGMs and lead and quickly came to the conclusion that even at a 1000 cycle life, Lithium beats lead all day long. A 100 AH cell is about equivalent to the most popular AGM capacity when figuring in the relative voltage sag of lead.

We will see soon enough!
 

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Discussion Starter #5
I couldent agree more Tim, im buying Batteries in the next 30 days (Need to get over the shock of spending 2500 on the rest of the drive system first) :)

But is is sort of disturbing to see the "mother ship" revising C rates..
 

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If you want to get long life out of them you need to size the pack appropriately. High discharge rates=short life or so I've read. Thus the recommendation of 0.3C discharge. I'm sizing my pack to operate normally on flat ground at 0.3-0.4C, with hills and acceleration going to 1, maybe 1.5C for a few seconds.

My truck will weigh about 3450Lbs with the new pack and use about 350wh/mile or so. The voltage I'm increasing to about 168V for extra range AND to lower the C because higher voltage = less current for a given Kw.
 

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8C for up to 10 seconds? I was going to set my controller for 4C max. I'm going to be at 1600 to 1800 lb total weight so I shouldn't need more than 4C except for going up and down to mountain passes. I live in a bowl at the lake and the only way out is over a mountain pass in any direction.

Are any of you guys aware of a cheat sheet of EV formulas. I should have written them down as I went along. How about a list of EV formulas in the FAQ?
 

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Never mind. I went back to the posted wiki and made a quick cheat sheet. I rewrote the battery sizing formulas backwards to allow me to plug in different wh/mi numbers and solve for range for a given battery rating.

I am using 1C instead of .4C for my battery amps. It seems to be pretty conservative. Agree?
 

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1C is much better than a lot of folks are using. I think most of that is probably due to people buying a smaller pack to save money, which is an issue no doubt, but prismatic batteries really aren't capable of doing hi C discharges without deteriorating the cell somewhat.

Calb, regarded as the best cell on this board I think, recommends discharging at 0.3C. If it were ok to run at 2C or more continuously don't you think they would post that? They don't because they want you to conserve the battery for longer life so they don't have to warranty cells I imagine.

I suspect 1C is fine as they probably have a built in cushion above the 0.3C for added measure but how much is anyone's guess.
 

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OK, I'm confused a bit. I was looking into getting a CALIB 180AH pack for my truck, 48 for a nominal voltage of 144V. The recommended discharge rate is .3C? That's only 54 amps. The spec sheet does say it can do 1000A for 10 seconds. My lead acid truck weighs in at 4000 pounds right now, it'll lose about 1300 pounds if I switch, but 54 amps isn't going to be moving me around fast enough to be useful. I had my limit set to 250 amps on the lead and it had OK performance, I was under the impression it would get allot better with lithium. What is a "reasonable" discharge limit for these cells that will still make them last?
Thanks,
TiM
 

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They will do 500A easily BUT if you want to maximize live for your $11000 investment you would want to keep it as low as possible.

Just an FYI, I'm ordering their 200Ah and they are just a tad shorter (180 I think) on the long side than the 180's (185?) so they will fit in the space of a lead battery easier.

My existing rack is made for 7.25" X 10.25" batteries. In each space left by a lead battery I'll be able to squeeze in two 200's with space left over. I think it's about 5 in place of two lead batteries. In any event I'm able to get 50 in my existing racks that now hold 22 US2200XC batteries.

I think they aren't selling so many 200's because they don't push them but they do fit better in existing racks than 180's.
 

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The general rule often heard for "prismatic" or "large format" cells (in contrast to smaller Ah cylindrical cells like Headway or A123) is no more than 1C for cruising, no more than 3-4C briefly during acceleration. This is not based on many years of data on cell lifetime versus discharge rate (we all wish!), but just what people think seems reasonable based on the manufacturer's spec's and some very spotty anecdotal data. So by this guideline, if you want to pull 250A in normal cruising you should use about 260Ah cells or larger. But 200 Ah cells would likely work without much hit on lifetime, but who knows?
 

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Tim,
Besides following all the li cell powered cars, I actually based my cell size on lead cars out there. I ran the calcs on the best AGM including all the derating factors in the FAQ. It showed that a typical lead cell was really about 100AH of usable capacity. That's why I am using 100's.

For your heavy lead truck, a set of 100's will give you equal performance, anything bigger will improve range or will improve acceleration if your controller can take the extra amps.

I also picked 100's because it's my first build and I consider it half of the pack I really want. Once I get it running, I may double it up with another set of 100's.
 

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Once I get it running, I may double it up with another set of 100's.
That was my thinking about a month ago when I was really mulling this thing over. After considering lifetime issues I decided to take the plunge and go for the 200. My cruise will be about 20-50A I suspect on nearly level roads. For hills I have seen nearly 300 trying to maintain 50mph. However losing 18% of my total curb weight after ditching the lead, upping the voltage & lowering sag, I'm hopeful to see a decline to maybe 200A or less on those hills.

My operating voltage will go from maybe 110-120V due to sag at 300A to maybe 150-160V with the 50 new Calb batteries at 150-200A.
 
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