I have a Sony VGP-BPS21A battery that I use to power my laptop. It is really old, like 5-6 years now and its cells have lost more than 50% of their capacity. As a new OEM is very expensive, hard to find and probably not recently manufactured, I decided to keep my battery controller and replace its 18650 cells.
So everything went fairly well, except I have broken the temperature sensor (a thermistor). Anyway, I have succeeded in fixing it and now my laptop powers on. However, it refuses to charge the battery.
I have checked some parameters my OS retrieves from the battery, and apparently it shows a capacity of 0.0Wh (previously 52.4Wh). I suspect important data was erased from the controller when I disconnected the old cells. I have googled some solutions to reprogram the controller, but only commercial solutions were found. Is there an easy solution to get the controller to charge the battery cells?
I have attached photos of the controller PCB.
IC1 is the MCU (R2J240 reference).