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What is the proper way to use 1 cell lipo batteries in parallel?

Discussion in 'Power Electronics' started by Farukh Khan, Sep 8, 2019.

  1. Farukh Khan

    Farukh Khan

    154
    2
    Jun 12, 2015
    Hello Guys,

    I am trying to use three 1 cell 12,000 mah batteries in parallel to get an effective 36,000 mah of capacity from them. But I only have a lipo charging and discharging controller circuit which supports one cell lipo only. So, what can be the proper way to use this 3 lipos together in parallel for high capacity and also, use the the same charging and discharging circuitry? Is there any BMS module or something which can allow me to do that?

    The battery I want to use is: https://uk.pi-supply.com/products/pijuice-12000mah-battery
    The charging and discharging module which I need to use is: https://uk.pi-supply.com/products/pijuice-zero - https://github.com/PiSupply/PiJuice/blob/master/Documentation/PiJuice_Schematic.PDF

    Please let me know how to proceed for achieving this goal.
     
  2. BobK

    BobK

    7,608
    1,648
    Jan 5, 2010
    3 12Ah batteries in parallel can be treated just like one 36Ah battery for the purpose of charging. Use a BMS suitable for a single cell of that capacity.

    Bob
     
  3. Farukh Khan

    Farukh Khan

    154
    2
    Jun 12, 2015
    @BobK If three 12Ah battery in parallel can be treated like one 36Ah battery, then why can't the same BMS for (battery charging and discharging) circuitry which works with one 12Ah 3.7V battery can be used for this parallel connected 36Ah 3.7V battery pack? Can you please explain?
     
  4. Audioguru

    Audioguru

    2,571
    580
    Sep 24, 2016
    A BMS designed for a 12Ah battery will charge at 6A and a BMS designed for a 36Ah battery will charge at 18A.
    But your little solar panels cannot charge at such a high current anyway so either BMS will take weeks to charge the battery.
     
  5. Farukh Khan

    Farukh Khan

    154
    2
    Jun 12, 2015
    @Audioguru the charging current is the only difference? My panels could not do a 6A charge anyway. So, does that mean I can do away with connecting parallel batteries on the 1 cell lipo charger? BTW, the charger I am going to use is mentioned in the top of this post.
     
  6. Audioguru

    Audioguru

    2,571
    580
    Sep 24, 2016
    Battery Management System ICs are designed to charge a high quality Lithium battery fairly quickly at a reasonable current of 0.5C. The Li-PO batteries I buy can be charged 10 times faster at 5C.
    Since the current from your solar panel is weak then it can charge parallel batteries fine but a full charge will take a long time.
     
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