Hello,
I am working on completing a learning cycle on a BQ27Z561-R1 fuel gauge with a 260mAh single cell battery (Chem ID 0x2817). It looks to me like the learning cycle has failed because the resistance tables are not updating during the discharge cycle. At the end of the learning cycle procedure the update status is stuck at 5 and is not updating to 6.
For this learning cycle my procedure was as follows:
- Send GAUGE_EN command.
- Send RESET command
- Discharge cell to empty - update status at 4.
- Relax until VOK and RDIS are clear, REST is set.
- Charge cell to full (~4.34V) - FC bit is set.
- Relax until VOK and RDIS clear, REST is set, update status at 5.
- Discharge at 31mA until empty (3.0V).
- Relax for 5 hours.
At the end of step 8, VOK is cleared and REST is set, but update status is not updated to 6 (still at 5). Do you know what we might have done wrong?
We chose the discharge rate to be at 31mA since the capacity of the cell is 260mAh, so this is above C/10 minimum discharge rate. The average discharge rate of our application is well below C/10, so we wanted to choose a lower discharge rate than the recommended C/5.
I've listed some key parameters below, and I've attached the .log and auto exported .gg.csv files from before and after.
| Design Capacity | 260 mAh |
| Design Capacity | 99 cWh |
| Charge Term Taper Current | 31 mA |
| Dsg Current Threshold | 3 mA |
| Chg Current Threshold | 24 mA |
| Quit Current | 1 mA |
| Term Voltage | 3000 mV |
| Design Voltage | 3800 |
| FC set voltage | 4300 |
| FC clear voltage | 4200 |
| TC set voltage | 4300 |
| TC clear voltage | 4200 |
| cell 1 chg@EOC | 4290 |
| Qmax Cell 1 | 260 |
| current at EOC | 31 |
| low temp charge voltage | 3800 |
| standard temp charge voltage | 3800 |
| high temp charge voltage | 3800 |
| rec temp charge voltage | 3800 |
