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bq24192 measure battery capacity

Giovanni Nervi
Prodigy 60 points
Other Parts Discussed in Thread: BQ24192, BQ27541-G1

Hi,

I have a smarphone Nexus 5 which use a BQ24192 for charge the lion battery. Can I use this chip for measure the capacity of battery?

I can't find a direct mode implemented in chip, but if I use the parameter INLIM from REG00 and monitoring CHRG_STAT from REG08 with an efficiency of 92% I can estimate how many current is in battery and which is the actual capacity

For example at charge of 900mA if the value of CHRG_STAT pass from 10 to 11 in 1 hour, the capacity of the battery should be 828mAh, for a while I ignore the fase pre-charge for battery low voltage.

Is it a good way for measure the capacity or is all wrong?

Thank you for your suggestions.

  • 0
    TI__Expert 8690 points

    Hi Giovanni,

    This chip is used for charging and does not have capacity measurements on the battery. If you want to accurately measure capacity, I suggest looking into the bq27541-g1 gauge.

    ++ I suggest looking into the datasheet of the battery to find its specifications.

    If you only want a really rough estimate of the battery capacity, you can use the charge curve and measure how much time it takes from CC to CV (not CC to charge termination). In the charge cycle, CV mode takes time to complete, so measuring time when in fast charge to charge termination may involve more complicated calculations.

    You can limit the current going into the battery with ICHG, have IINLIM a bit higher than ICHG just in case, and measure the time it takes from 3V to VREG-20mV. Then Capacity = ICHG * time(hours). Be careful not to overcharge the battery, make sure you are charging to a reasonable voltage.

    What is your setup to make this test if I may ask? Also, if you are not sure how to do this, I don't recommend it. Either look for the datasheet or don't do this procedure, you might damage the battery and/or have an unpleasant result.

    Thanks,
    StevenB

  • 0 in reply to Steven Bangdiwala
    Prodigy 60 points

    Hi Steven,


    thank you for your reply. This chip is used in my smartphone Nexus5, so I can't change nothing, I can't add none chip, also registers are setuped by Android, so I can only read. Today thank you post, I discovered there is another chip not TI which can help me to understand the actual capacity of battery.


    Giovanni