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BQ34Z100-G1: charging NiMH

Rafael Zamacola
Prodigy 20 points
Part Number: BQ34Z100-G1
Other Parts Discussed in Thread: BQ2000,

Hello,

We want to improve a prototype by adding the bq34z100-g1. The prototype in question has 6S NiMH cells with a bq2000 smart charger IC embedded in it, if we use the bq34z100-g1 do we have to change the smart charger (bq2000) to a constant switch current regulator? I ask this because my understanding is that with a smart charge IC, the charge could end before the bq34z100-g1 detects a full charge so the fuel gauge would never equal RemainingCapacity() to FullChargeCapacity()-

Thanks.

  • 0
    TI__Guru 73830 points

    The bq34z100-G1 does not support broadcast mode to control a smart charger. If will detect charge termination and set a flag in the Flags register. The host can read this register and command the charger to stop. The gague also has the Charging Current and Charging Voltage parameters that can be read by the host. They are update per the JEITA charging profile stored in the device.

  • 0 in reply to ThomasCosby
    Prodigy 20 points
    If I have undestood you ok, the bq34z100-G1 and a smart charger are incompatible and the way to go is to implement a dumb source current controlled by the host (with the help of the charge termination flag). Is this correct?

    PD: I didn't mention in the first post, but the bq34z100-G1 will be in the system side (not inside the battery pack).

    Thank you for your help!
  • 0 in reply to Rafael Zamacola
    TI__Guru 73830 points
    That would be one solution for the charger. This gauge does not support broadcast mode to communicate with a smart charger.

    The gauge can be used in a host side system. It will run a capacity simulation and update RM, FCC and SOC when the cells are attached. The accuracy of the simulation will be dependent the accuracy of the ChemID match and how well the cells have relaxed. The gauge can also update the Ra tables and Qmax after a new set of cells have been attached. It may take a few charge and discharge cycles to fully optimize these parameters for the best accuracy.