I bought a used Oset at the weekend for my son. Its a 12.5 model. I put it on charge and let him have a bit of a go out the front of our house as its very quiet. After a few minutes the bike would barely pull him up a small hill in the road. I put it on charge when we got in and it was on for about 8 hours but the red LED on the charger never turned green to say it was fully charged. I took it off charge and lifted the back wheel whilst I turned the throttle. I held it for about 30 seconds and you could hear the wheel gradually turning slower. The following day I left it on charge over night and still no green light. Do you recon the battery needs replacing?
When I lifted the back wheel and gave it some throttle whilst the bike was still on charge there was no signs of the wheel slowing down.