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BQ24193: Charging 2 Li-Po cells in parallel, with this chip

Erick Minnie
Prodigy 80 points
Part Number: BQ24193

Support Path: /Product/Development and troubleshooting/

Hi All

We are using the bq24193 in industrialised product (thus not possible to change chip now) and have run into problems with our battery manufacturer.

The battery we have used up to now is a single cell 7200mAh 3.7V Li-Po.

The closest replacement I can find with very short lead time, is a battery pack consisting of 2 x 3000mAh Li-Po batteries in parallel giving me 6000mAh.

Will I be able to charge them reliably with the bq24193?

They do not have balancing circuits on either, only over-under voltage-current protection.

  • 0
    TI__Expert 8230 points
    Hello Erick,

    A 1s2p configuration such as the one you are describing is still considered a single-cell application and would work with the bq24193, as long as the charge current and regulation voltage thresholds are still within the bq24193 operation range.

    I would make sure the 1s2p pack is made with well-matched cells to avoid issues such as impedance mismatching that can affect run-time as the cells age. Cell balancing is mandatory for cells in series configuration.
  • 0 in reply to Fernando Lopez
    Prodigy 80 points
    Thank you Fernando.
    If anything should go wrong with one cell then the over-voltage/current or under-voltage protection PCB that is on the battery terminals should protect that battery from excessive discharge as well as overcharging, right?

    We have set up the bq to charge at either 512mA or 1A when device is powered, and allow 2A charge when device is off.
    The 2-cell pack allows a 0.2C normal or 0.5C fast charge, which should then be OK at 1.2A dn 3A respectively.

    When on, our maximum continuous current is about 3.5A which should be enough for the 2-cell pack they specify as 1C discharge (ie. 6A)
    And maksimum peak spikes are about 5A, still OK with their 6A.

    Any problem with my reasoning?

    Many thanks in advance.
  • 0 in reply to Erick Minnie
    TI__Expert 8230 points
    Hello Erick,

    Your reasoning is correct.

    The battery pack should have primary protection ICs built into it, you would need to verify with the pack's datasheet to see the specifics, but yes, there should be at least 2 FETs, one for charge and one for discharge control that would control when the pack can charge/discharge safely and would take care of over-voltage and under-voltage as well.

    The bq24193 has secondary protection: BATOVP, over-current protection, and thermal protection as well. The 5A discharge spikes shouldn't trip the bq24193's BATFET OCP, but I would verify the discharge thresholds on the pack's protection to make sure it's within its spec.
  • 0 in reply to Fernando Lopez
    Prodigy 80 points
    Thanks Fernando, this will then work for us.