Melted battery connector

[WibbleWobbleWoo]

Hi,

Just thought I'd post here about a worrying development with my solar setup that happened on Sunday 20th October. As Octopus were offering free electricity that afternoon between 1pm-2pm I'd confirgured the presets to charge my battery up during the free hour. I was away at the time but got home shortly after 2pm to find a burning plastic smell in the room where the inverter and batteries are installed. I immediately powered down the whole system.

First thing Monday morning I called my installer and he said he'd come out the next day to have a look. When he got here he immediately spotted the problem, the battery connector on the underside of the inverter had partially melted (see photo). I guess it had been arcing while charging and got rather hot. Who knows how long this had been happening. I have a FireAngel connected smoke alarm above the inverter but it hadn't gone off, obviously wasn't enough to trigger it.

My installer is hoping to replace the battery connector if Fox can supply him the part. Otherwise I guess the inverter would need swapping out under warranty. Once it is fixed though, I'll be visually checking everything frequently as it wasn't something I'd even thought about, and if my setup was up in the loft where they'd wanted to install it I wouldn't have even known it was happening.

Cheers,
Russ.

[Dave Foster]

You are lucky that you noticed it, and looking at the picture it appears that the front battery connector hadn't been pushed all the way home as it would have been held by the clips like the rear connector - if the connection was then loose, there would have been arcing when high loads switch in or out which would make the problem worse over time and it sounds like your force charge was the last straw.

This goes to show that it is always worth a quick visual inspection to make sure the PV and battery connectors are pushed in and locked with their clips... i'll just go and check mine now.

Best of luck getting this resolved quickly.

[WibbleWobbleWoo]

Quick update: Had a brand new H1-3.7-E-G2 inverter fitted on Tuesday and everything is up and running again. After my installer left I double checked all the connectors are fully seated and clicked in, which they are.

Incidentally, does anyone know what the latest firmware versions are for it please? It has Master 1.23, Slave 1.02, Comm 1.38 on it right now. If that isn't latest, are there any new features/enhancements to be had by requesting an upgrade?

Cheers,
Russ.

[Dave Foster]

The latest are Master 1.29, Manager (Comm) 1.44 - not a lot behind but as it is a relatively new inverter they will mostly be operational fixes (some to the way it handles solar power when force charging) I would recommend that you upgrade at your earliest - your installer can do it remotely, or email Fox service with your inverter serial number and they can update for you.

[SolarMonkey7]

I found the same issue today. Positive terminal to my battery completely melted through to expose the cores. Same issue found on the battery positive terminal connector also!!!
I have a 7kW KH7 inverter and 12.44kW of ECS battery (1x master, 2x slaves). The charging current is rated to 50A, but the 6mm connection cable might be too wimpy to handle this kind of energy. I think the connection on the battery is now unrepairable, we may need a replacement.
It's only come to light as the winter has arrived and I've opted to charge the battery overnight.
Installer has been contacted, but battery is now isolated. A near miss (luckily) but this could have been far more serious.
From these two cases, it would infer that the manufacturers cable/connection choice is inappropriate for the power/amp rating. I have operated this system in accordance with the manufacturer's guidelines and installers guidance. I wonder how many others are about to expose this hazard during the 'heavy battery charging' winter season?

Chris

[Will]

Very concerning to see your photos of the melted connector. Clearly if not an install mistake, it's a manufacturing issue for a batch of cables.

[WibbleWobbleWoo]

Wow, yeah, so not an isolated issue then. On a possibly related note, I was reading the user manual for my new inverter and noticed this section regarding wiring:

Now I'm unsure which part the warning is for, PV above it or battery below it, but all the wires that go into my inverter are bent close to the inverter. Could this be the actual problem?

[Will]

Wow, yeah, so not an isolated issue then. On a possibly related note, I was reading the user manual for my new inverter and noticed this section regarding wiring:

Screenshot 2024-11-24 202457.png

Now I'm unsure which part the warning is for, PV above it or battery below it, but all the wires that go into my inverter are bent close to the inverter. Could this be the actual problem?

Correct, they added that warning in the latest version of all the inverters. I wonder if overbent cables which is known to increase resistance is causing this issue.