MP2672A in a 2S2P charger configuration

Battery Management
1

Greetings

I am building a custom charger board and to double my system’s capacity, I’m considering switching from a basic 2S 18650 battery configuration to 2S2P (so adding 2 more batteries in a parallel). I’m wondering if this is possible with the MP2672A charging chip. Something like what I added to the Standalone Mode schematic from the datasheet:

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I’m aware of the recommendations to have the batteries from the same manufacturer and around the same voltage level to start with. On the MID line, I have a 100R resistor and I have the system configured to charge the batteries up to 4.2V per cell. The balance option is enabled and the system runs in Standalone Mode.

Are there any other recommendations I should add to my design when doing a 2S2P configuration? Is it possible to do? I feel like it is, but let me know if there’s a critical flaw in my thinking.

2

Hi Antun,

Your new parallel configuration should work with the MP2672A. However, the parallel batteries will be balanced as though they are one cell (i.e., your new cells cannot be actively balanced independently of the cells they are in parallel with, as the active balancing is measured at the MID line). The parallel cells will passively balance each other. As you mentioned, please ensure that the cells are as close to each other in charge (within ~10mV, if possible) before connecting them in parallel.

Please also ensure that the new battery quiescent current meets the spec provided in the datasheet. It may also be recommended to add an external charging circuit, as described in figure 15 of the datasheet:

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3

I can confirm that it does work.

Thank you.