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Original question:

BQ34Z100-G1: Can I use this part for 2S, 3P cell configuration

BQ34Z100-G1: Multiple Battery Packs

Paul_Marco
Prodigy 165 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQ25713,

Hi there,

Our product has 3 battery packs. Each battery pack is 2s2p and has three wires that connect onto the main board, see image below.

We plan on using the BQ25713 for charging, but cannot decide on a fuel gauge.

1. Will the BQ34Z100-G1 work system side with 3 separate packs connected together at the main board?

2. We notice there is only a single thermistor input, how do we handle the case of having 3? (one for each pack)

  • 0
    TI__Mastermind 24870 points
    No, I suggest separate gas gauges for each pack in this situation. The bq34z100-G1 is designed to assume packs are perfectly balanced based on the simple voltage division. If you want accuracy, you should consider pack side gas gauges for each pack.
  • 0 in reply to Kang Kang
    Prodigy 165 points

    Hi Kang Kang,

    I'm not sure if we have the budget or footprint space for 3 of these circuits.  What if we make sure the packs are at equal charge levels before connecting them?

    Are there any other system side chips that could work with this?

    If we can find packs that have a pack-side fuel gauge, I assume they have i2c wires as well?  Can we still use the BQ25713 and just communicate to each of the packs for their charge levels?

    Edit: Also, let me clarify that we don't plan on hot-swapping batteries. The 3 packs will be connected once during assembly and will stay that way for the lifetime of the product.

  • 0 in reply to Paul_Marco
    TI__Mastermind 24870 points
    The system side solutions may work, but I just worry about cells coming disconnected from your system.

    Unfortunately, the gas gauges from TI all have the same I2C address. We don't have any gas gauges with programmable I2C addresses at this moment. I've highlighted this to the systems team.