diffcamp wrote: ↑
Nov 08 2018 8:19pm
The battery is 36v and 20 Ah.
The charger is 42V and 2A. It doesn't have a voltage selector switch
It doesn't need one. 42v is the full charge voltage of a typical 36v pack.
When I took the battery out of the box, the indicated had only 1 flashing red light. This means it's not charging and it has 0% - 10% charge. I plugged in the charger, but the charger has a light that means "Disconnected or full charge." I left the charger plugged in for an hour and a half, nothing changed.
The battery won't stay on for more than a few seconds unplugged.
I tested the charger with a multimeter, I measured 42V which matches the spec, and It put out brief spikes of 2A. The rest of the time it's 0A. I'm guessing those spikes are how it determines if it should charge or not.
It sounds like the battery has a problem internally--the most likely thing is that at least one cell is so low that it is causing the BMS to shutoff pack output.
The charger turning on and off could indicate the BMS is trying to allow charge, but that a cell (or several groups) is hitting the HVC (full) point very quickly, and shutting off charge until it is drained a bit by the BMS balancers. This commonly happens to unbalanced packs where most cells are very full, but one group has a problem and is very low or empty.
You could leave the pack on the charger until it begins charging normally; this could take days to weeks depending on how badly imbalanced the pack is.
But since its a new pack, it shouldnt' have this problem, so I'd recommend first contacting EM3EV to see if they have specific things they want you to check first, but it sounds like you've done everything you can without opening it up.
If you open it up you can measure all the individual cell groups (at the balance wires to the BMS), but I don't know how this affects their warranty.