Did you check the cell voltages under load? Quite often the very poor BMS/balancing system allows a cell to get either very over voltage charged or dragged below 0v wrecking the cell. A replacement out of something else gets the battery back to useful again. Best to add a Junsi cell logger across the cells so you know if a cell is getting thrashed.Peter and Sandra wrote: ↑Sun Oct 07, 2018 6:18 pm I've had similar experience to NP.
I bought a lithium battery for my quaddie a couple of years ago and after 12 months or so it would not crank it over quick enough when the engine was cold unless it had just come off charge and then only for about 30 seconds, if it didn't start then it had to go back on the charger.
I went through everything, cleaned and checked the starter, all battery connections etc etc to no avail, pulled the same size LA out of the mates quaddie and it started first push of the button. The lithium battery now runs the electric fence and the battery out of it (same size) now starts the quaddie every time on the first go.
T1 Terry