Which battery cells are better - cylindrical or...?

[alex_h]

Thinking about building my first battery pack myself and I wonder what type of cells to use. I thought actually about Lithium Polymer but I noticed that there are two types.

1. Cylindrical

2. Flat ones.

I suspect with the flat ones I could get more amps hours fitted in the case but I wonder are there any benefits from cylindrical over flat ones?

Anyone, any help much appreciated.

regards

Alex

 

[flecc]

One of the most touted advantages of lithium cells is that they can be made any shape, so much more flexible for designers.

Based on that I'd guess it doesn't matter, and in an case many today are soft pouch cells like those in this pack:

 

[eddieo]

Sounds interesting......So come on Alex spill the beans what is the plan

 

[alex_h]

thinking about problem logically it seems to me that the cylindrical cells should better distribute the heat since these have an empty gaps between cells so the heat can easily run away?

On the other hand the question is how much of this heat actually there is and if the cells really get hot. Assuming that the discharge rates on the ebike are rougly 0.5C with 250W motor than the amount of heat should not be as significant, is it or is it not and how hot get the cells?

Was it Daniel Weck that has built his own battery pack with A123 cells or someone else? He should now more about it.

Still looking for a better option

regs

Alex

 

[NRG]

Well it's not that important, the RC flat lipo cells are capable of 30c discharge rates and they survive well despite being soft plastic packaged. In a typical e-bike you would be hard pressed to reach 3c discharge rate.