BQ27542EVM: SOH Drop Issue

Tom Tsao

Part Number: BQ27542EVM

Tool/software:

Dear TI support team,

I am using the BQ27542 for a discharge test and found that the SOH suddenly drops.

Why did the SOH suddenly drop from 100 to 97 and then further decrease to 93? After starting charging, it increased back to 97.

Please provide the reason for this sudden SOH drop. Additionally, how is SOH calculated and when does it update?

Attached are the log file and gg file.

Thanks!

12.gg.csv

3755.log.xlsx

6 months ago

0 Tom Tsao 6 months ago

Expert 1840 points

Dear TI support team,

Do you have any updates?

Thanks!

0 Alan Frias 6 months ago

TI__Mastermind 25225 points

Hello Tom,

this question has been assigned, and we will get back to you soon

Regards,
Alan

0 Tom Tsao 6 months ago in reply to Alan Frias

Expert 1840 points

Hi Alan,

Do you have any updates?

Thanks!

0 Tom Tsao 6 months ago in reply to Tom Tsao

Expert 1840 points

Hi Alan,

It has been more than 4 days. Is there any new update regarding this issue?

0 Adrian 6 months ago in reply to Tom Tsao

TI__Mastermind 37761 points

Hello Tom,

SOH is usually updated when Qmax or Ra tables update. Now, the main parameters that affect SOH reading are SOH Load rate and design capacity. Design capacity should be set to the value stated in the datasheet. SOH load Rate should be set to the typical load that the application will see. Based on the log file, I would set this to -3500. SOH load rate is currently set to -7000 which could be the cause of SOH to change erratically.

Regards,

Adrian

0 Tom Tsao 5 months ago in reply to Adrian

Expert 1840 points

Hi Adrian,

Thank you for your reply. I now understand that this is caused by the SOH_LOAD I setting. Could you please explain in detail why it is set to -3500mA? In the future, I will have different load conditions, so I need to know how to set it accordingly.

Thanks!

+1 Adrian 5 months ago in reply to Tom Tsao

TI__Mastermind 37761 points

Hello Tom,

The SOH_LOAD_I should be set to the typical current draw that the gauge will see. I told you to set it to -3500mA since this is the value I saw in the log file you sent originally. If the final application will have a different load current, then that register will need to be changed.

Regards,

Adrian

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BQ27542EVM: SOH Drop Issue