BQ41Z90-FW: Learning Cycle and SOC

Hi Tobias,

Looking at the log file, I believe you never reach learn status 6 is because your voltage reading is not completely stable after discharge. For larger packs it is not uncommon for this to take over 5 hours for the cells to fully relax.

Regards,

Diego

Hi Diego,

the log file was not from the learning cycle, it should just show that the SOC doesn't change. Because of this my question from above "Is it possible to perform a successful Learning Cycle with the FW Version 0x0002?"

Regards,

Tobias

Hi Tobias,

Tobias Jung said:

the log file was not from the learning cycle, it should just show that the SOC doesn't change

That could be due to a variety of reasons, including a poor chemid match. We can diagnose SOC performance after the learning cycle is complete.

Tobias Jung said:

s it possible to perform a successful Learning Cycle with the FW Version 0x0002?"

Yes

Regards,

Diego

Hi Diego,

I tried again to perform a learning cycle; I changed the SOC Flag Config A to 0x0c33 and the SOC Flag Config B to 0x0033 so that the [FC] [TC] [TD] and [FD] get set by voltage.

It seems that after the charging the Rest bit doesn’t set although the voltage change is at about 2,17 µV/s what’s below the stated 4 µV/s from the SLUA848.

Here are some screenshots

After the first discharge

Rest over night

End of first charge

End of log before letting it rest overnight

Rest over night

Rest and log over day with 2.17 µV/s in the log

Rest over second night

• [REST] doesn’t set

I attached the log files from charge discharge and rest?

What must I change to get the rest bit set after charging?

Regards,

Tobias

LC_Rest_after_First_CHG_0C5.logLC_First_DSG_2C.logLC_First_CHG_0C5.log

Hi,

After discharging, your batteries are not fully relaxed. the rest bit will set once an OCV measurement is taken.

Regards,

Diego

Hi Diego,

what is missing after the discharge? I let the battery rest over night after the discharge and as show in the second picutre the rest bit was set

Regards,

Tobias

Hi Diego,

after two more cycles the LStatus changed to 0x06 so the BQ learned:

But unfortunately, the SOC just jumps from 100% to 0%. Any suggestions on how to improve the fuel gauging?

LStatus_0x06.xlsx

Regards,
Tobias

Hi Diego,

this is Nick, a colleague of Tobias.

Please find attached the gg.file.

Best regards and thank you.

Nick

Read_8S_0_07_LStatus_0x06.gg.csv