[coryrc]

Anybody know of a small LiFePO4 cell, maybe 1Ah or even less?

Preferably actually available.

Testing BMS on 40Ah cells is starting to get a little old...

 

[JRoque]

Sure! Here's one: http://www.batteryspace.com/lifepo4-rechargeable-14430-cell-3.2v-400-mah-0.4a-rate-1.28wh.aspx

Hopefully you'll be able to adjust the current resolution for your testing from the now 40Ah to 400mAh.

JR

 

[Yabert]

You can purchase a lot of A123 1.1 Ah 18650 on ebay.

 

[coryrc]

Sure! Here's one: http://www.batteryspace.com/lifepo4-rechargeable-14430-cell-3.2v-400-mah-0.4a-rate-1.28wh.aspx

Hopefully you'll be able to adjust the current resolution for your testing from the now 40Ah to 400mAh.

JR

Have you tried them? Do you think it is 1C/400mA or 0.1C/40mA, as they say "0.4A/0.1C"...

 

[coryrc]

You can purchase a lot of A123 1.1 Ah 18650 on ebay.

I hadn't thought of that, thank you. And only $2/Ah!

Too bad they're so damn hard to connect together. Any suggestions?
Packs are really expensive and mostly the 2.3Ah cell.

 

[frodus]

well, why does the design require small cells? if you went larger format, they'd be easier to assemble

I would NOT solder them, you should weld those style cells.

 

[coryrc]

well, why does the design require small cells? if you went larger format, they'd be easier to assemble

I would NOT solder them, you should weld those style cells.

Just for BMS testing. Sure, I have several hundred running around in cars, but I'd like to do more bench testing for future designs, including full cycle tests, which is where the 40Ah cells get really annoying...

 

[vpoppv]

Just for BMS testing. Sure, I have several hundred running around in cars, but I'd like to do more bench testing for future designs, including full cycle tests, which is where the 40Ah cells get really annoying...

Do what I did and open up laptop batteries. Super cheap and readily available....

 

[MN Driver]

Do what I did and open up laptop batteries. Super cheap and readily available....

Careful these are Lithium Cobalt and not LiFePO4, there are additional considerations to using these cells. You aren't going be able to draw high rates from laptop cells either, they do sag a bit and get hot quickly with high discharge rates. Going outside of their voltage range isn't forgiving for LiCo like it is with LiFePO4. Drop below 2.8 volts and you may be in for a serious surprise the next time you charge.

 

[coryrc]

Do what I did and open up laptop batteries. Super cheap and readily available....

In addition to what MN Driver said, I would like to test with the actual chemistry the BMS will be used with.

It looks like one of the sellers on EBay will weld tabs on for me! I'll see how it goes...