Victron BAT5214130410
my goto next step is to buy one of the new victron ip65 chargers @ 5a, and try giving that a bunch of time. I have another BAT5214120410 from the same batch that’s been in use and still going strong, so I wouldn’t mind picking up one of the ip65 chargers anyway, if there’s any chance this might bring this just-uncrated-yet-already-old battery back
Worth a try
0,5V at the terminals are 0,12V at the cells.
You may be able to get the battery back to "life" but you will never can use the full power of the battery. The cells are damaged.
Only charge the battery under supervision and as soon as possible connect a BMS to the battery.
