BQ27426: BQstudio CHG/Discharge cycle error

JoFu10

Part Number: BQ27426
Other Parts Discussed in Thread: EV2400, BQSTUDIO,

Hi,

I am trying to cycle the battery around 100 times to see the fuel gauge accuracy performance.

I am currently using BQstudio+EV2400+BQ27426EVM. However, I keep getting some charge or discharge errors if I try to cycle more than 1 time. 1 charge+1 discharge seem to be fine. Could you please point me to some possible cause?

Thanks,

Josh

over 7 years ago

0 Onyx Ahiakwo over 7 years ago

TI__Guru* 76230 points

hi Josh,
What is the capacity of your battery? Can you try using a smaller taper current , eg 50mA and a 200mA charge current to see if the problem occurs.

thanks
Onyx

0 JoFu10 over 7 years ago in reply to Onyx Ahiakwo

TI__Intellectual 2385 points

Hi Onyx,

The battery is 520mAh. We have tried with different lower taper currents and we are still getting the same error.

Thanks,
Josh

0 Damian Lewis over 7 years ago in reply to JoFu10

TI__Mastermind 34775 points

Hi Josh,

A reasonable taper is < C/40, so for 520mAh cell that's < 13mA. Also try a longer relax time after charge and discharge.

0 JoFu10 over 7 years ago in reply to Damian Lewis

TI__Intellectual 2385 points

Hi Damian,

Sure I will try this. I've seen somewhere that the guide for taper current is fast charge current/10. Is <C/40 a better rule?

Thanks,
Josh

0 Damian Lewis over 7 years ago in reply to JoFu10

TI__Mastermind 34775 points

Hi Josh,

Yes <C/40 is better and will help charge to full capacity the lower the taper current is. We use C/100, but it depends on the charger's current resolution capability.

0 JoFu10 over 7 years ago in reply to Damian Lewis

TI__Intellectual 2385 points

Hi Damian,

We are still seeing errors when discharging with 10mA taper current and 10min relax time for Charge/Discharge. See below:

Wed Nov 29 18:46:24 EST 2017: Start Task: Discharge ( Terminate when TerminateVoltage = 3300 )

Wed Nov 29 19:41:34 EST 2017: End Task: Discharge completed in 00:55:09 - Termination Voltage Reached

Wed Nov 29 19:41:34 EST 2017: Start Task: Relax ( Terminate when Duration = 10 )

Wed Nov 29 19:51:34 EST 2017: End Task: Relax completed in 00:10:00

Wed Nov 29 19:51:34 EST 2017: Start Task: Charge ( Terminate when TaperCurrent = 10 )

Wed Nov 29 22:13:35 EST 2017: End Task: Charge completed in 02:22:01 - Taper Current Reached

Wed Nov 29 22:13:35 EST 2017: Start Task: Relax ( Terminate when Duration = 10 )

Wed Nov 29 22:23:35 EST 2017: End Task: Relax completed in 00:10:00

Wed Nov 29 22:23:36 EST 2017: End Task (Unexpected): Discharge - false

Wed Nov 29 22:23:36 EST 2017: Start Task: Discharge ( Terminate when TerminateVoltage = 3300 )

Wed Nov 29 22:23:38 EST 2017: Complete!

Thanks,

Josh

0 Damian Lewis over 7 years ago in reply to JoFu10

TI__Mastermind 34775 points

Hi Josh,

Can you provide a log, gg and srec file for me to review? What is your taper rate and taper voltage set to in bq27426 data flash? What's your dsg, chg and quit current threshold set to?

0 JoFu10 over 7 years ago in reply to Damian Lewis

TI__Intellectual 2385 points

Hi Damian,

Sent it to your email.

Thanks,
Josh

0 Damian Lewis over 7 years ago in reply to JoFu10

TI__Mastermind 34775 points

Hi Josh,

This might be a GDK issue. Can you try upgrading to the latest GDK EV2400 firmware from BQ27GDK000EVM?

www.ti.com/.../BQ27GDK000EVM

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BQ27426: BQstudio CHG/Discharge cycle error