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Old 09-01-13, 06:16 AM   #1
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Charging two packs in parallel

Soon I will have 2 LiFePO4 (48V) packs on one of my bikes with the discharge ports connected in parallel. One pack is 14ah and the 2nd is 10ah.

Is there any problem with having the charge ports on these connected in parallel and charging these packs together simultaneously with one charger?

Someone told me I shouldn't because they have different ah ratings, but it seems to me the BMS on each pack will manage the charge going to each, and the charger will just continue until the "average" voltage of the 2 packs reaches the cut-off point (i.e. both are fully charged).

Anyone have any experience or even theoretical feedback on this?
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Old 09-01-13, 08:27 AM   #2
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Take a look at the PDF from Ping at

I would charge each separately due to the fact you have two different Ah ratings as your previous source recommended. Send Ping an email if the PDF doesn't answer your questions.
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Old 09-10-13, 04:53 PM   #3
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Different Ah is not an issue in parallel (it can be a serious issue when connected in series) but it is just not an issue connecting different capacity batteries in parallel to charge as long as they are same voltage. in fact any bike that has a battery that's made up of several strings of cells is already doing it as the charger doesn't know if its for example 3 x 2Ah batteries or 1x4Ah +1 x 2Ah.

BUT .....i think to have two BMS boards in the circuit fighting each other to control the chargers on/off switching is just asking for trouble, i wouldn't do it if only because i think charging might take forever because the charger would be trying to do almost all the work on trickle (green light on).
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