BQ28Z610-R1: SOC display problem when temperature resume from -20 degree to 20 degree

Hello, 

Is there a protection event that is occurring?

Can you also please describe the test procedure in detail? 

Have you successfully completed a learning cycle? 

Regards, 

Jonny. 

Our SOC 0% is 3.4V and 100% is 4.2V. the attachment is the gg file.

We thought that the SOC jumped to 0%, because the battery voltage once dropped under 3.4V .

The battery have been completed a learning cycle by chem ID which was replied by our battery manufacturer.

The test procedure is that device is booted up at -20 degree.

We charge the SOC of device to 100% at room temperature. Then, we will let device to discharge to the target SOC.

When SOC reaches the target SOC, we will shutdown the device and put it into the chamber which is -20 degree.

After heat balance(about 4 hours in the chamber), we boot up the device at -20 degree, and observe that if the each target SOC could be booted up into the android  desk.

According to the experiment, the device could be booted up into android  desk at -20 degree when the SOC is above 70% at room temperature.

When SOC is below 70%, the device couldn't be booted up into android  desk at -20 degree. During boot up process, SOC will jump to 0%, because the battery voltage drop under 3.4V. Then, our system will shutdown due to SOC 0%.

After then, because the SOC is 0% already, device will not be booted up even if the temperature goes up 20 degree and battery voltage is above 3.8V. 

Does it have any way(set some registers) to let SOC value to return to normal value when the temperature become warm except full charging?

Does anyone else have a similar issue? How was it resolved?

Thanks.MP70HH1_Rev_A5_V1.02 2025.01.16.gg.csv

Ian Lee.