Third day as daily and Battery Alarm sounds

On was on my way home last night and stopped at a major intersection to turn right. When I got the green arrow and moved off, the battery alarm alert started. I pulled over as soon as practical and popped the bonnet. (I do not yet have my controller keypad in the cabin which tells me which of three regions in the car the alert came from). All the blue lights were still lit on the engine bay packs. I moved around to the boot - and it was LOCKED. So I turned the car off, unlocked the boot (I needed the key from the ignition) and got back in and started driving again. The alert started within 10 seconds. I stopped again and checked the boot packs. Pack #4's light was off.

At this point I should have bypassed pack #4 which would have taken all of two minutes but for some foggy reason I decided to limp the 3 km home.
I got home OK (annoyed a bit of traffic) and checked voltages on all packs. Most packs were 52.4 VDC. Pack #4 was 36 VDC. In my mind I had clearly ruined some cells.

I placed the car on charge and within a few seconds the charger light for pack #4 showed it was fully charged. Hmmm. To cut to the chase, the inline fuse from the charger to the pack was very hot and the fuse holder was melted and at a strange angle.

The diode isolator and inline fuse assemblies for the chargers.

This is the second fuse holder that has melted - I replaced the one on pack #12 about three weeks ago. These fuses only take 3 Amps but it appears to be too much for the el-cheapo fuse holder.

I pulled the diode/fuse assembly out and soldered in a fuse directly and heatshrunk it with a couple of layers. I then placed pack #4 back on charge. It didn't get hot at all after that. Pack #4 took a full 3 Amps for more than 6 hours so it clearly survived and I learnt some helpful clues.

Clue #1
According to the smart meter online monitor, the night after my 60 km day, the house drew 3 kW for an hour then 2.7 kW for 3 hours. The clue was that one charger had dropped out after the first hour (smartmeter resolution is 0.1 kW).

Clue #2
On the drive home, several kilometers before the alarm, the full pack voltage was dropping under 600 VDC regularly. I had not even seen that on the 60 km run, except under really heavy load. Now I know to pay attention.

Clue #3
No so much a clue as observation. Don't skimp on parts - especially cheap ones. I'll replace all the fuse holders as time permits and solder the fuses directly into the assemblies.

There are obviously down sides to the one-charger-per-pack system but the alert system obviously works fine. I need a reliable wireless mains power monitor for the EV outlet - the one I have is rubbish due to the non-linear power factor issue with the chargers (I think I'll crack the sender open and see what I can change/fudge).

The battery alarm drives you insane - it's very loud. I was originally concerned that you wouldn't hear it because it's up under the dash somewhere. The alarm also locks in and can't be cancelled without turning the car off - not hard to change but I'll see how it goes - It normally shouldn't go off anyway..

I am now carrying a short bypass cable and the tools to bypass a pack (and a multimeter) - the Vogue can run on as little as nine packs (I have twelve).
Yesterday's battery to wheel was 7.22 AH for 32.06 km => 132 wh/km
I drove the Vogue in again today.