PLUS and V1 have LiFePo4 battery, that's known for its long life. But if it fails for some reason (water damage?) - visit this section.
V1/PLUS BATTERY
If your PLUS battery died (and you're 100% sure it's not the BMS, which takes care of the battery pack and keeps it balanced and running), here you have a perfect replacement.
Availability: only a few left!