[somanywelps]

Originally Posted by winzeracer

Do you think pack will last at least 250 cycles with a max 10C draw and 3C continous? ( with a decent algorithm style charger)

It's the heat that kills the cells, not the draw....

[frodus]

Keep that 10C draw less than 10 seconds and keep the continuous as low as possible. Try not to stay in the 3-10C range a lot.

I think you could get 250 cycles out of them, but it sounds like you might be wanting to hammer them hard.

Put it together, try it out, and dial the controller to about 200A to start, then slowly go up. Invest in a clamp on current meter (or a shunt meter) with a PEAK HOLD function so you can see what you hit while riding.

What do you intend to use to charge 26 cells?

[winzeracer]

Originally Posted by frodus

Keep that 10C draw less than 10 seconds and keep the continuous as low as possible. Try not to stay in the 3-10C range a lot.

I think you could get 250 cycles out of them, but it sounds like you might be wanting to hammer them hard.

Put it together, try it out, and dial the controller to about 200A to start, then slowly go up. Invest in a clamp on current meter (or a shunt meter) with a PEAK HOLD function so you can see what you hit while riding.

What do you intend to use to charge 26 cells?

I would like to find a diy charger kit, or use a elcon pfc-5000 so I could charge quickly( .5-.7C). I know that you are very knowledgeable in this area. Is this ok to do in your opinion?

Thanks,
Brock
Www.winzeracer.com

[frodus]

But realize a PFC running full bore on a discharged pack at 5000W is going to be charging those cells at almost 1.5-2C. A bit much for those cells if you want to keep them healthy. Also, 5000W won't work out of a normal 120VAC outlet, it'll blow the fuse. I'd suggest getting a 1500W version.

DIY charger kits could be done (not sure what you're considering), but I think you'd spend more and put more time in assembly than is worth for a smaller project like this.

Consider getting something like an Elcon/TCCharger (from me) or DeltaQ from here: http://www.diyelectriccar.com/forums...ghlight=deltaq
I can reprogram the DeltaQ for your voltage.

[winzeracer]

Originally Posted by frodus

But realize a PFC running full bore on a discharged pack at 5000W is going to be charging those cells at almost 1.5-2C. A bit much for those cells if you want to keep them healthy. Also, 5000W won't work out of a normal 120VAC outlet, it'll blow the fuse. I'd suggest getting a 1500W version.

DIY charger kits could be done (not sure what you're considering), but I think you'd spend more and put more time in assembly than is worth for a smaller project like this.

Consider getting something like an Elcon/TCCharger (from me) or DeltaQ from here: http://www.diyelectriccar.com/forums...ghlight=deltaq
I can reprogram the DeltaQ for your voltage.

I am ok with 220V input, I would like to be able to quick charge at the track in ~2hrs. Any recomendation?

Brock

[frodus]

I'd aproach it in reverse. The datasheets for CALB 40Ah cells say 12A recommended charge. I wouldn't charge over that, so do a 0.3C charge. So 12A on a 72V pack is about 7-900W. So just about anything over 800W.

I wouldn't try to quickly charge these cells, especially without a BMS. One cell can (and will) charge quicker and overvoltage.... if it does that, while the others are slowly charging, the cell WILL go thermal. These cells are meant for low current charge and a 3-4C discharge continuous. Don't go outside of those specs or you'll really risk losing cells, either all at once, or one at a time. Keep it at 0.3C or close to it. No need to go 220V input, just get a 120V 1000-1500W charger and call it good. I've got several models available if you want, both 120/240V (they autoswitch) programmed for your pack.


If you go the other way around, and want a full charge in 2 hours, you need to put about 3328Watts (approx size of your 26s1p 40Ah pack) into the pack if you discharge to 100%, which you shouldn't. At that much energy, you'd want to do about 1600W per hour. But the first hour needs to be more because as the voltage increases, the current decreases once you hit CV. So I'd size to something like a 2000W charger. Now, 2000W at ~72V lets say, is going to be about 28A, or about 0.7C, over twice the recommended charge current.

Risky, but it's all your decision. I'd keep it under 1000W. You underdesigned your system, I wouldn't push it!

[winzeracer]

Originally Posted by frodus

I'd aproach it in reverse. The datasheets for CALB 40Ah cells say 12A recommended charge. I wouldn't charge over that, so do a 0.3C charge. So 12A on a 72V pack is about 7-900W. So just about anything over 800W.

I wouldn't try to quickly charge these cells, especially without a BMS. One cell can (and will) charge quicker and overvoltage.... if it does that, while the others are slowly charging, the cell WILL go thermal. These cells are meant for low current charge and a 3-4C discharge continuous. Don't go outside of those specs or you'll really risk losing cells, either all at once, or one at a time. Keep it at 0.3C or close to it. No need to go 220V input, just get a 120V 1000-1500W charger and call it good. I've got several models available if you want, both 120/240V (they autoswitch) programmed for your pack.


If you go the other way around, and want a full charge in 2 hours, you need to put about 3328Watts (approx size of your 26s1p 40Ah pack) into the pack if you discharge to 100%, which you shouldn't. At that much energy, you'd want to do about 1600W per hour. But the first hour needs to be more because as the voltage increases, the current decreases once you hit CV. So I'd size to something like a 2000W charger. Now, 2000W at ~72V lets say, is going to be about 28A, or about 0.7C, over twice the recommended charge current.

Risky, but it's all your decision. I'd keep it under 1000W. You underdesigned your system, I wouldn't push it!

Frodus,

I realize now that I totally under designed this. I work with people in my line of work that want to push the specs too. It is a pain so I appolgize for all the hypothetical questions. And realize that this is not a great way to design a system. But now that I am locked into what I already bought I kinda need to reach a bit. So I will heed all warnings and not go too extreme.

Can you get me a price on a 1500 watt Elcon or Delta-Q, programed for 26 cells to charge at 16 amps? In compromise for the .4C charge I will run a Mini-BMS, unless you have another option I should look into?

Again, thanks for all you help,

Brock
www.winzeracer.com

[frodus]

I'm not saying you can't get it working, sorry if I came off abrasive. Just wanted to make sure you had all the data first so you can decide if you want a pack to last 1500 cycles, or if 10 was ok

I'll PM you

[winzeracer]

Hey all please see new post here
http://www.diyelectriccar.com/forums...ion-74588.html

Thanks,
Brock

[winzeracer]

Yabert found this motor only 26lbs and 50kw Agni 111rdr
http://endless-sphere.com/forums/vie...440&hilit=agnI

Brock
Www.winzeracer.com