Hello all,
I have issues to complete the learning cycle for a 2p LiFePo4 battery pack (A123 APR18650M1A, 1100mAh). The gauge was programmed with ChemID 404 and data flash parameters configured to match LiFePo4 voltage range.
When performing the learning cycle, update status successfully updates from 0x02 to 0x04 and 0x05. Qmax also updates as expected. FC was set after charging. But after the final discharge cycle and relaxing for more than 9 hours, update status still did not change from 0x05 to 0x06. RUP_DIS and VOK both were clear at this point, only OCVTAKEN was set.
When looking at the diagram below, I wonder if the relax times after charging / discharging even need to be increased further (currently around 8 hours) since there is still some change in cell voltage noticable.
There are some remarks I need to add. Can you please comment, wether one of these items might be the reason for the failed learning cycle and what needs to be changed?
- I did not change the "Flash Update OK Cell Voltage", still at 2800 mV
- Not charging with strict CC/CV profile; charging circuit goes into thermal foldback, so charging current starts at 2000 mA but is significantly reduced, as the charger chip heats up (clearly visible in diagram)
- Although the battery is rated for cut-off and charge voltages of 2V and 3.6V, it is only discharged to 2500mV and charged to 3530mV. For the learning cycle, is it required that the full voltage range as given by the cell datasheet is crossed?
Do you have any hints how to continue, before starting the next learning cycle?
See Learning Cycle log and dataflash export files for reference below.
Thank you and best regards,
Daniel
Learning cycle log:
2019-08-16 Learning Cycle 1.zip
Data Flash Auto Export Files: