Running Parallel batteries

[Brendon1128]

Right now Im running a 48v 10ah battery which Im commuting to work on (25 km or so each way)  the problem is for the first 15-20 km it runs great, but towards the end of my journey theres a noticable drop in power. Ive put about 5500 kms on the battery so over the past year so its probably lost some of its capacity.

I recently ordered a new 48v 15ah pack from the same seller I worked with on ebay last year. Its the same type of batteries (18650 li-ion cells) Im wondering if its possible to connect these two packs to make a super long range 25ah pack. Is it bad to hook up a used pack to a new one? Also, how would it work with the bms system?

[Bikemad]

As long as the packs are the same voltage it shouldn't cause any problems connecting them in parallel. If one pack is weaker than the other it simply means that the stronger pack will be doing more of the work but they should still discharge evenly together.

It shouldn't affect the BMS of either battery as each BMS will only be monitoring the cells within its own battery.

The only thing you need to be careful about is not connecting the batteries together in parallel while they are at different voltages (one partly discharged and the other fully charged etc..)

Alan
 

[Scooter]

I would ask the battery manufacturer--or company from which you purchased the batteries--how the BMS would be affected. Just to be sure...