HELP! battery won't turn on or charge

Hi EPFMs,

I just had a battery failure and I don't know what's going on.

Last night I set up my watt meter with expression wires sho that I can finally know my amp draw under load.

Today, it was going well but then it just stopped dead. At first, I thought it was one of my phase wires. My green pass wire did come loose. I was about to change to a new controller anyway. I packed it with me for emergency situations like this.

Only problem was that my battery wasn't even talking to my watt meter.

I tried connecting directly to the controller with no response. I changed the connector on red wire of the battery.

After several hours, the system won't turn on not will it charge.

Is this a bms issue?

I'm currently on my way home where I'll be pulling the thing apart to see if I can figure it out.

Alright. Update on the situation. After arriving home, I immediately opened up the battery and the first I checked was the continuity of both discharge leads.

Turned out that while the black was solid, the red wasn't. The new connector wasn't making contact. So I pulled this guy off and put on a fresh one after stripping the wire a couple of mm more so the strands can reach the metal plates of the connector.

Easy fix but it didn't explain why it wasn't taking charge earlier.

I then tested the charger and worked perfectly.

After using a multi meter to make sure it was solid, I proceeded to seal up the casing. And just when I'd finished tapping up every seem, I checked the voltage again to make sure but this time it showed something like 19 volts.

I plugged it in to the watt meter and it wouldn't respond again. So I had to open it up again and started checking the bms and the voltage of each pairing seemed okay. Around 3.7-3.9 volts. (Though I didn't do a thorough check because I kept accidentally sparking a couple of them and I know I can ruin some cells like that)

For a while, it kept toggling between having full voltage (51.7 on a 48v battery) to showing 19v or sometimes 9v.

Eventually, it got steady again and proceeded to put the battery back on the bike. Took it a 12 km test ride (with a new controller. Quite pleased with it ) and everything seems back to normal.

I wish I could say it was just a bad connector but the truth is that I have no idea. It started with one phase wire coming loose. I've had phases come loose on me in the past and it's never been enough to shut down my battery like this.

But I have had it shut down momentarily in the past when I was struggling with bullet connectors and power poles. Usually, the battery comes back to life in a few minutes.

Has any of you had similar experience? Is there a cause I'm not seeing? Because I don't want run into this issue again. I'm really scratching my head.