I am re-submitting this issue, as the issue has been closed before resolution has been reached.
**** To recap the problem:
Our medical product suffers from a small proportion of deployed Li-poly batteries swelling up, which generates too many returns.
Changing to a more robust battery technology is a long term aim, but the short term strategy is to minimise the issue. I have been trying to derate the charge termination voltage from 4.2V to 4.1V and to reduce by half the maximum rate of charging. This is possible because the charger is programmable.
However the battery gauge does not cope well with the change. It is important that the gauge reads 100% charge level when the charger terminates at the lower 4.1V level. Initially I hand edited the .gg file and reduced the design capacity, CC Threshold and qmax values by about 15% (wrote it into the gauge, performed a reset, allowed an OCV measurement), but at charge termination the gauge still reads a charge level in the mid eighties percentage. Perhaps it would eventually self-adjust the qmax etc after repeated cycles?
My next effort was to perform the bqEasy process of the bqEVSW software. However in the learning cycle it gets stuck because at the end of the charge phase, the gauge refuses to set the full (FC) bit and that prevents the software progressing to the discharge phase.
**** The following advice was posted by Onyx Ahiakwo
Hi Jeremy,
You did not need to make those changes you made. If you are reducing your charge voltage, all you need to do is charge the cells to that voltage and ensure you reach primary charge termination based on taper current and have the FC flag get set. If that happens, the gauge will adjust the cell chg DOD at EOC and adjust 100% to that charge voltage. You may have to run a full discharge and charge cycle to get it to update properly.
