BQ28Z620EVM-071: BQ28Z620-LEARNING CYCLE

puppala naresh

Part Number: BQ28Z620EVM-071
Other Parts Discussed in Thread: BQ28Z620

Tool/software:

Hi Team,

I am currently working on completing the learning cycle to achieve accurate State of Charge (SOC) estimation on BQ28Z620 EVM BOARD. I have enabled the fuel gauge and am using a 2S1P battery configuration.

Here are the key configuration details:

Cell Over-Voltage (COV): 4200 mV
Cell Under-Voltage (CUV): 2500 mV
Design Capacity: 3000 mAh
Design Energy: 2220CWh
Charge Termination Taper Current: 250 mA (default)
Discharge Current Threshold: 45 mA
Charge Current Threshold: 40 mA
Quit Current: 10 mA
Termination Voltage: 6V

During the learning cycle:

After charging, the Update Status changed from 0x00 to 0x04.
After a full discharge, it updated to 0x05.
The device is now in relaxed mode, but the Update Status remains 0x05 and is not transitioning to 0x06.

Additionally:

During charging, the reported battery percentage increases gradually from 1% to 100%.
However, during discharging, it always shows 100%, and does not decrease.

I have attached the log files for reference.

Could you please help me understand what steps I should take next to successfully complete the learning cycle and resolve the SOC reporting issue?

Charging_Discharging_Cycle.log

4 months ago

0 Alan Frias 4 months ago

TI__Mastermind 27405 points

Hello Puppala,

If you update status is stuck at 0x05 and can't update to 0x06 status than reference the FAQ attached below.

[FAQ] Why is the Update Status register not updating from 5 to 6?:
https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1263623/faq-why-is-the-update-status-register-not-updating-from-5-to-6

Thank you,
Alan

0 puppala naresh 3 months ago in reply to Alan Frias

Prodigy 100 points

Hello Alan Frias,

I've completed the learning cycle, and the update status is now 0x06. All flags are working as expected.

However, the battery percentage displayed is still incorrect. It reaches 100% when the battery voltage is around 3.7V or 3.8V, even though my Cell Overvoltage (COV) threshold is set to 4200mV (4.2V). Conversely, the percentage drops to zero when the battery voltage is 3.3V or 3.2V my CUV is 2800mv.

I've attached my log files for your review. Could you please examine them and let me know what the issue might beCharging_discharging_LOGS_UPDATED.log 0407.roomtemp_rel_dis_rel.csv

0 Alan Frias 3 months ago in reply to puppala naresh

TI__Mastermind 27405 points

Hello Puppala,

I've received your update and working throughs a response.

Thank you,
Alan

0 puppala naresh 3 months ago in reply to Alan Frias

Prodigy 100 points

Hello Alan,
Can i get any update?

0 Alan Frias 3 months ago in reply to puppala naresh

TI__Mastermind 27405 points

Hello Puppala,

Did you do the learning cycle with an aged cell? Based on the .log file you sent it shows the SOH to be 62% which is pretty fairly aged in terms of battery. Please try to use a new cell.

Thank you,
Alan

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BQ28Z620EVM-071: BQ28Z620-LEARNING CYCLE