BQ27421EVM-G1A: Validate BQ27421YZFR-G1A ?

Verifying SOC can be done with a constant known discharge current from a full charge. You can calculate the state of charge by integrating the passed charge. SOC = 100 - 100 * (passed charge) / (full charge capacity).

The gauge should not report 0% at 3600mV (unless there's an error in configuration). Are you able to get correct SOC readings using the EVM and bqStudio?

Dear dominik,

Thanks for suggestion regarding my first question i.e SOC validation, I have tried the same thing, Let me explain :

My total battery capacity is 900mAH , i charged it full and i have started Discharge cycle and my board , my system consuming 75mA average current and system remains running till 11H 53M.

So, if we calculate total power consumed by system than it is : 11.90 * 75mA = 892mAH.
And SOC reading decreases 100-0% gradually. you can observe the same through attached Log file.

SOCdata_bq_DischargeCycle_3.xls

So should i can say Fuel gauge reports perfect SOC ?

And regarding my second query that is regarding Cut-Off voltage :

Pardon for that i didn't get you, you said (there's an error in configuration) means i am not able to write I2C register or data i had written to register was may be wrong ?

At present i am using EVM for reading.

From you log data it looks like the SOC is ok. Please verify the capacity settings. Did you configure the gauge for approx. 892mAh? If that's the case and the coulomb counter counts up to 892mAh before the voltage reaches VTerm then you'll get SOC = 0% before VTerm. If you run several cycles (full charge to termination voltage) with relaxation of approx. 2 hours in between then the gauge will update the chemical capacity and the SOC will reach 0 closer to VTerm.

Hi Dominik,

Pardon for the late reply,

I have configured capacity settings to 900mAh.

So, You are saying that It's also possible that i will get SOC=0%, even if battery voltage never reaches to Termination Voltage value.Please correct me if i misunderstood something.

So to resolve this do we need to update Chemical capacity Or Gauge will update it automatically ?                            

Regards,                                                                                                                                                             Keval

The gauge will update the chemical capacity automatically over time (make sure you discharge/charge your battery and relax for at least 30 minutes).

Thanks Dominik for clarification,

I also wants to know about FC bit(9th bit) of flag register 0x06.

As per TRM ,slusb85 it is mentioned that FC bit will set when %soc value will reach to >= FC value(default 100%)
But in my case this bit is not being set even after soc value reach to 100%, Is there any know reason behind this ?

Regards,

Keval.

Please check the value of FC Set %. If it is -1 then FC will only be set if the Charge Termination conditions are met.

FC Set% value was -1% , but i have configured it to 100% ,and i have double check the configuration through Reading it again. Its updated , but then also FC bit is not being set even after SOC reached to 100% ?

Is there anything we missed to configure ?

Regards,
Keval.

Hi Domini
Have you got the chance to look into the case ?

Regards,
Keval