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Solar Powered Parallel Li-Ion Cells Charging

George Ioakimedes
Genius 4950 points
Other Parts Discussed in Thread: BQ24210, BQ25504

I must be missing something because I can't seem to find any products or reference designs which show the charging of a system that has cells configured in parallel. Because of the end product's shape we were thinking of making a pack that might consist of maybe 3 in series and then running 2 or 3 strings in parallel. All of the chargers and gas gauges I've looked at only talk about cells/batteries configured in series.

  • 0
    TI__Guru* 76230 points
    Hi George,

    You aren't seeing anything because cells in parallel can just be considered as 1 single cell unit so there isn't any specific consideration to take unlike with regards to charging or gauging unlike when you have cells in series where the voltage will increase as the number of cells in series increases. From a gauging perspective, as the number of cells in parallel increases the capacity increases and that is accounted for in the gauge in the design capacity register.

    Let me know if you have further questions

    thanks
    Onyx
  • 0 in reply to Onyx Ahiakwo
    Genius 4950 points
    Hi Onyx,

    Thanks for the quick reply. But if you have the cells in parallel, what happens when 1 cell doesn't charge or charges differently? I thought at the beginning of the charge cycle a CC method is used and then it switches to CV?

    I was thinking of using the BQ24210 but that doesn't boost and we want to use a single solar cell (0.5V/2A) so maybe I need to use BQ25504?

    Thanks,
    George
  • 0 in reply to George Ioakimedes
    TI__Guru* 76230 points
    Hi George,
    You will need to post your charger related question to the charger forums. Yes, charging is CC/CV so your cells will be at the same voltages if they are parrallel. that is why you need to make sure you are using the same type of cells that are in a balanced state
    thanks
    Onyx