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BQ25505: Is BQ25505 compatible with NiMH batteries ?

Sebastien Boisseau
Prodigy 20 points
Part Number: BQ25505

Hello. 

It seemed obvious but this is not mentioned anywhere in the datasheets :

 Is BQ25505 compatible with the recharge of NiMH batteries ? Is there a way to handle NiMH batteries in series or in parallel with BQ25505 ?

With many thanks.

  • 0
    TI__Genius 10385 points

    Sebastien,

     

    Because of the fixed VBAT_UV of 1.95V, the NiMH batteries would have be in a 2S (two cells in series) configuration to be used with this device.

     

    Thanks,

    Ricardo

  • 0 in reply to Ricardo
    TI__Mastermind 30150 points

    Hi Ricardo,

    About the difference in charging profile between NiMH and Lion:
    -Is the charging curve of the BQ25505 ok for 2S NiMH serie?
    -It seems that the termination detection is different for NiMH (temperature or voltage sensing) compared to LiOn (current sensing).
    Will the BQ25505 termination detection work for NiMh? Any tip to implement and check the termination detection work for NiMh?

    Anything else to take into account?

    Thanks in advance!

    A.

  • 0 in reply to AnBer
    TI__Genius 10385 points

    Anber,

    bq25505 charges the battery in pulses as power is available from the source. This should be fine for the NiMH battery. The bq25505 terminates based on the voltage seen at VSTOR. Charging will stop when VSTOR reaches VBAT_OV. VBAT_OV can be programmed by the resistor network. This termination process is shown in Figure 12 of the datasheet.

    Thanks,

    Ricardo