Yeah the issue is as I described above
The Swappable Storage battery is |.
Maybe when it was in the vehicle you took it out of, it wasn’t draining, but usually when you reinstall a battery in that condition, the game assumes it is, just like the fuel tanks. 
Sadly, storage batteries (40k variant) are not repairable, so you will have to remove it and discard it entirely, as it will never charge in that vehicle otherwise.
Good news is, it’s very easy to find more of those, and there’s always a chance you can find a specific vehicle that has an 80k version of it