[da.2022]

Hello, the plastic melts between the battery and the battery lead positive underfloor.
It's happened twice already. I have to repair it for the 3rd time now.

1. there has been a fire in the back area of the battery

2. I repaired the damage but it happened again

What do I have to do to stop this from happening again? what am I doing wrong?

many thanks for your help.

[Unspec]

Sounds like something is drawing far too much power. That said, the fuses should have popped before anything started to melt or catch fire. Is the car fully stock?

Edit: What year car is it?

[Node]

If that happens just while car is standing, you have really heavy short somewhere... In this case battery should be drained within minutes. I DON'T think any fuses could pop, because there are none on this cable... Even if they were, they would be sized for starting currents (like 1000A) and this could be like 20A short...

If that happens only while you are trying to start a car, then it could also be that cable is damaged and just has too high resistance...

[da.2022]

It is the 1st generation F80 M3 2014.

I drove the car normally, it smelled of fire.

Error message
Battery resistance too high

After the first repair I drove about 60km with it.

All fuses are intact.

I was still lucky. But what do you think I did wrong? I plan to replace the cable next week. but it scares me?

[Node]

And how it happened second time?

I would definitely suggest to properly check charging system. Just to make sure it's not pumping 18V+ into battery (like when alternator regulator is shorted).

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Also check battery if some cells are not shorted inside so even proper charging voltage causes hundreds of amps charging current...

P.S. You need proper knowledge AND specialist equipment for such checks so unless you are electrician or want to invest - find someone who knows what he is doing.

[Unspec]

I'd also double check to make sure battery is properly coded to the car, including correct battery size.

[da.2022]

I took a wiring harness from the M3 accident car. I also took over the positive terminal to the battery from the accident victim.
Therefore I had the error message restraint system

Could this be because the positive terminal of the battery cable was bridged?

Battery has 13.9V
Auto voltage delay on diagnostic delay at 13.2V

I am an electrician. I have to repair my M3 myself. I'll be replacing both cables next week.

I think I used a wrong adhesive that is conductive. is just a guess.

I'll observe the area with a thermal imaging camera.

[Node]

I'd also double check to make sure battery is properly coded to the car, including correct battery size.

And WHAT would that change exactly??? Unless someone recoded it to normal battery while it still has Li.

[da.2022]

Hallo

I'd also double check to make sure battery is properly coded to the car, including correct battery size.

It is the lithium battery for M3 M4
I took it from my other M4. I only took a positive pole cable from the accident car for the 60km test drive, or maybe from the epoxy glue? the screw was stuck and burned. I didn't code the battery to the car

[Node]

Wrong AH coding or "not coding battery to a car" CAN'T melt wires!!!