BQ27426: State of Health setting (0x20,0x21)

Feng bin Su

Expert 8670 points

Part Number: BQ27426
Other Parts Discussed in Thread: BQSTUDIO

Hi team,

My customer is evaluating our BQ27426 for their battery system.

They read the state of health value of 0x20,0x21 by BQstudio ass below figure.

The read back value is 64 and 00. According to document, customer think that 0x21 value is invalid if it is 0.

Hence, they would to confirm with you whether their understand is correct. If it is correct, is there reason to induce this invalid value? Calibration file?

Sorry I am not very familiar with our gauge and need your kindly comment about it.

Best &Regards,

Ben

over 2 years ago

0 Shirish over 2 years ago

TI__Guru 57697 points

Hello Ben,

The value in register 0x21 is the SOH status.

SOH 0x20 returned 0x64 = 100%

SOG status 0x21 returned 0 (not valid, initialization). This means that the SOH value of 100% is not valid because the gauge is still being initialized. You can only get valid SOH value after learning cycle is completed

0 Feng bin Su over 2 years ago in reply to Shirish

TI__Expert 8670 points

Hi Sirish,

Could you help to check the log as attached? They don't know why does 0x21 is still 0 when they have finished the learning cycle.

They are doing the preproduction for this. It may stop the production schedule.

data memory_20221103.gg.csv 5861.Registers.log

0 Shirish over 2 years ago in reply to Feng bin Su

TI__Guru 57697 points

Hello Ben,

What is the design capacity?

0 Beginner over 2 years ago in reply to Shirish

TI__Intellectual 2381 points

Hi Shirish,

The design capacity is 5000mAh. As customer mentioned, they did set update status to 0x3 before learning cycle starts and the status is changed to 0x0 after learn cycle is done. Qmax and Ra is updated too. Thus, supposedly the symptom is not relative to learn cycle.

Meanwhile, I found another E2E thread to mentioned same case. Steven Yao mentioned the SOH_Status code is removed. Could you double confirm?

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/852595/bq27426-state-of-health-function-enable/3179969?tisearch=e2e-sitesearch&keymatch=bq27426%252525252520SOH%252525252520Status#3179969

The only concern for customers currently whether the SOH is still updated even if SOH status is 0. May I have your comment?

0 Shirish over 2 years ago in reply to Beginner

TI__Guru 57697 points

Hello Ben,

The SOH was updated in the log and was reported correctly (with design capacity set at 5000mAh).

The SOH status byte is normally not used. I would have suggested to ignore it. Since Steven confirmed that it was removed, you must ignore it.

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BQ27426: State of Health setting (0x20,0x21)