Ebike amps

[Parsons]

Hi guys a friend at work won't to build a ebike from new new bike and conversion kit. I know a bit about batterys and controllers does the amps of the battery have to match the controller etc or does the battery or controller have to be higher

 

[Benjahmin]

Controller will have a maximum rating. The battery should have the ability to deliver at least this amperage (ideally plus 10-20%) as a continuous rating - not as a peak rating.

 

[Parsons]

So if his battery bms is 40 amp what is the maximum controller amps

 

[Nealh]

So if his battery bms is 40 amp what is the maximum controller amps

30a would be ideal.

 

[Parsons]

Thanks for the info I will pass it on to him what would happen if he got a 35 to 40

 

[Nealh]

It depends on the cells used and how many in parallel, if the cells were 20a rated cells then one could use a 40a rated controller. But if the cells are only 10a rated or less then they would be operating at their max current rating and at the max or above temperature rating for them.
So for safety 30a, but as I mentioned depends on the cell rating and how many in parallel.

 

[Parsons]

I've just text him he's looking at 52v nominal 20ah with 40amp bms from unit pack power not Samsung etc I think it's just grade A cells