• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 63 subscribers
  • Views 651 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ27410 SOC/RM values

Eugene Gavrilov
Prodigy 50 points


Hello,

Our device uses BQ27410 for measuring battery capacity. We've recently faced one issue: when battery is charging, sometimes BQ27410's SOC ("State of Charge") and RM ("Remaining Capacity") values suddenly become either 0, or SOC=100%, RM=0. So, for example:

ITEMP=37C; VOLT=3626 mV; RM=293 mAH; AI=-616 mA; SOC=8% (battery is charging)

(after some time):

ITEMP=37 C; VOLT=3625 mV; RM=0 mAH; AI=-624 mA; SOC=0%

After such event, RM starts increasing again. At a later stage, RM/SOC might "restore" their normal values.


Another problem, probably related: during charging, SOC immediately becomes 100%, RM becomes 0, and BQ27410 signals "Full Charge" bit.

What could be wrong?

I suspect it might be related to some current fluctuations which cause BQ to think "full charge" has been reached. (Taper current? Taper voltage?)

Any hints are welcome!


  • 0
    TI__Mastermind 24870 points

    Hi Eugene,

     

    Have you looked at the Flags() register to check to see if BAT_DET is set? The gauge will report always report 100% SOC if this bit is not set when you insert the battery.

     

    Also, can you check the capacity of your battery? Also, check the value of Qmax in dataflash. Are they the same?

     

    Thanks,

    Kang Kang

  • 0 in reply to Kang Kang
    Prodigy 50 points

    Hello Kang Kang,

    Thanks for the hint - yes, BAT_DET is set. Our current observation show that this bug seems to be closely related to this bug: http://e2e.ti.com/support/power_management/battery_management/f/180/t/269283.aspx

    We had to decrease I2C speed in order to fix both issues: I'm still very curious to know, why only register 0x41 was affected by I2C speed (and all other registers were read correctly). It is also strange that any delays introduced -between- I2C reads did not fix the problem, but delays between each I2C bit fixed them. Looks like this is some kind of very deep BQ feature, which is causing specific register read failures and subsequent SOC/RM resets.

  • 0 in reply to Eugene Gavrilov
    Prodigy 150 points

    Hi all.

    We are also using the BQ27410 circuit and have seen the SOC and RM values suddenly go to zero. If we can fix this with lowering the I2C speed it would be great.

    Can You tell me which colck speed You are using when it is running correct?

    Thanks,

    Knud Erik