LiPo Battery question

[TurnNBurn]

I'm building an electric motorcycle (see my other post(s)) and I'm just curious about LiPo batteries. I'm still leaning towards LiFePo4, but LiPo has my curiosity since I like to know how things work. I see LiPo batteries have 2 power terminals and then there's some sort of data connection. What is this data connection for?

[Smurf]

I quickly checked a few R/C websites for LiPo information, and it seems it's the "Balancer Wire". Check out this site: R/C Calculations and then change the "Series Connections" to 2S.

Hope that helps.

[TurnNBurn]

Originally Posted by Smurf

I quickly checked a few R/C websites for LiPo information, and it seems it's the "Balancer Wire". Check out this site: R/C Calculations and then change the "Series Connections" to 2S.

Hope that helps.

Thanks. That clears up what it is. Now I have more questions.

I was previously (as in a year ago) considering getting some LiPos and running 4 batteries in a series and then parallel them in a group of 4. So 16 batteries total. Would I have needed 4 balance boards for those 4 series batteries?

[Daox]

Really, a 16 cell balancer would be best. If you get 4 4 cell balancers, and the 4 balancers don't 'talk', you would have 4 different balance levels.

Also, I would suggest sticking with LiFePo4. Their life in traditional applications is way longer than LiPos. RC battery packs aren't meant to handle thousands of cycles.

[TurnNBurn]

Originally Posted by Daox

Really, a 16 cell balancer would be best. If you get 4 4 cell balancers, and the 4 balancers don't 'talk', you would have 4 different balance levels.

Also, I would suggest sticking with LiFePo4. Their life in traditional applications is way longer than LiPos. RC battery packs aren't meant to handle thousands of cycles.

I do plan on sticking with LifePo4, but i was just trying to wrap my head around this whole Lipo thing. I was just curious. It's my nature.

[NeilBlanchard]

I'm a neophyte on this, but I recently heard about do bottom balancing instead of BMS, as a way to keep it simple, and lower the stress on the cells. Maybe with a smaller pack, getting all the energy possible stored is more important? Kevin Smith was the referring to the 99 cell pack of the Thundersky/CALB 100Ah cells.

[puddleglum]

A lot of the ebike racers run lipo because they are light and have really high C rates, but they are also more volatile (read prone to thermal run away and spectacular fires if pushed beyond their limits) and have much shorter cycle life. Even the strong advocates of lipo on ES say to use caution when charging.

[oil pan 4]

My LiFePO4 batteries have been good to me.
With only 4 in series no need to fret over charge balance.

What C rate do you want to run?