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BQ27421YZFT-G1A state of charge and state of help

Hardik Madhu
Prodigy 195 points

Hello all,

We are using BQ27421YZFT-G1A with a 95mAh Li-ion battery. We are reading the following things:

Temperature is 3043
voltage is 3854
Flag is 0
Nominal Available capacity is 95
Full Available capacity is 95
Remaining capacity is 45
Full Charge capacity is 45
Avarage current is 50
Standby current is -3
Max load current capacity is -200
Available power is 189
State of Charge is 100
Internel temperature is 3043
State of Health is 0


Our Problem is that State of Charge is always 100 and State of Health is always 0.

Can anyone point out the problem??

Thanx in advance.

Hardik

  • 0
    TI__Mastermind 24870 points

    Hi Hardik,

    Can you log using EVSW or GaugeStudio the following registers?

    1. Voltage()

    2. Current()

    3. Temperature

    4. State of Charge

    5. Remaining Capacity

    6. Flags

    7. Full Charge Capacity

    8. Control Status

    9. Nominal Available Capacity

    Start logging before you apply current, and log for one hour once you discharged at your 50 mA rate.

    Can you also send us a copy of your GG file?

    From initial observation, your Flags should not be zero. I think there is something wrong with your setup. Can you please explain how you are getting your data?

    Thanks,

    Kang Kang

  • 0 in reply to Kang Kang
    Prodigy 195 points

    Hello Kang Kang,

    Thanx for replying. 

    We will log readings according to your instructions.

    But before that can you tell me what do you think can be wrong with our setup??

    And I found out that because of Taper Rate,  We are getting same values of Remaining capacity,
    Full Charge capacity and because of that State of Charge is always hundred. 

    Can you please tell me how to calculate Taper Rate??

    Thanks,

    Hardik Madhu

  • 0 in reply to Hardik Madhu
    TI__Mastermind 24870 points

    Hello Hardik,

    Normally this is based on your charger tolerance.

    Say you have a 2000 mAh battery. As a rule of thumb, we would need to taper at C/20 or 100 mA in order for the battery to be fully charged at room temperature.

    In the gas gauge, we will use taper rate to detect Full Charge. So if you want a taper rate of 100 mA for a 2000 mAh battery. That means you should set your taper rate to 200, the units are in 0.1 Hr Rate.

    Hope this helps!

    Thanks,

    Kang Kang