MP2759 for multiple battery packs?

Hi, I’m trying to design a backup battery solution that will fit into an existing space within our product. I believe that 3 x protected 21700 cells in series will give me 11.1V nominal at approximately half the capacity I need and there is room for two such packs in the available space.

I would like to use the MP2759 for charging and power path management - can I charge both 3S packs in parallel from one MP2759, or should I use one charge controller for each battery pack and combine the outputs downstream? Charging time is not critical and the current available for battery charging is limited by the input power supply, so the current drawn by two packs in parallel would not over-stress a single MP2759

I’d be grateful for any advice you could offer

Hello rml,

You could charge the two parallel packs with one MP2759. You recognize that there will be a slower charging time and that are current limitations.

However, I am worried about cell/pack balancing. With the parallel connection, there is no guarantee that the packs will be charged equally. It may be fine if you are using the same battery.

I would recommend using the 2 MP2759 and combining the outputs downstream.

Vinh Tran