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Melted cables/fire when charging leisure battery from zig
Posted: 16 Jul 2023, 15:49
by Brockybwoy
Help
I've just had my van engine rebuilt after years sitting on the drive and getting it ready for it's 1st camping trip .
I bought new batteries and wired up the new DAB radio, lighter socket and clock to the leisure battery to bottom fuse connector (position3 in fusebox ) with an in line 5 amp fuse.
This morning I connected the mains hookup turned on the fridge and switched the ZIG to on -site to top up the the battery (I'd had the radio running for several hours over last couple of days ) . The fridge quickly got cold and multi meter confirmed that the battery was charging at a steady 13v I left it on whilst I went inside to make a cuppa and when I came back could smell burning . I saw that there was smoke coming from battery box . A hole had melted in the side of battery (which was leaking acid ) and cables were burned I disconnected everything and found that live and earth cables had burned all the way back to main battery box and that edge of carpet had burned along with edge of wood flooring underneath . The RCD circuit breakers which I tested this morning hadn't tripped
I'm now wondering if it was my redirection of radio from main to leisure battery , damaged wiring or faulty zig unit that caused the fire ?
Feeling very gutted but at least happy whole van didn't go up in flames any suggestions ?
Thanks
Re: Melted cables/fire when charging leisure battery from zig
Posted: 16 Jul 2023, 16:15
by Mocki
So the wires between the main battery and the leisure battery melted ?
That wouldnt be anything to do with the radio rewiring , or that would be where the melting would be
Split charge relay would be the first place i would look , or charger ?
Re: Melted cables/fire when charging leisure battery from zig
Posted: 16 Jul 2023, 17:17
by Oldiebut goodie
Battery connections were reversed somehow?
Re: Melted cables/fire when charging leisure battery from zig
Posted: 16 Jul 2023, 18:13
by Brockybwoy
Thanks for quick replies
split charge relay is little green box in main battery compartment ? It looks ok but of course I'll find out how to test it . The battery definitely wired right way round . I've been running radio ,interior lights and usb charging through lighter socket adapter for 3 days . In the 20 years we have had the van I have only tried using mains hookup once. It didn't work, I blamed the cable and put it on "to fix" shelf in garage This morning I pulled it out ,cleaned all the terminals with switch cleaner /wet and dry paper and did continuity test . Everything was ok so plugged it in . It still didn't work so i had a nose in cupboards under sink and saw that the RCD switch was off . I didn't even know there was one in there

.
I flipped the switch and for a couple of hours ran the fridge, a 240v spotlight and the radio thinking the battery charging circuit was fine too . It's possible that the charger in the Zig and / or the cables from Zig to leisure battery damaged .Looks like a "bar-steward" to rewire so I'll take it to electrical specialist . If it's the charger I'll have it disconnected and charge the battery with smart charger I use for the car through mains plug
Re: Melted cables/fire when charging leisure battery from zig
Posted: 16 Jul 2023, 18:47
by Stesaw
Personally I'd dump the zig and get new victron or similar 240 -12v battery charger and a switch panel. I would have thought the RCDs should have tripped so perhaps they are also faulty? How old are they? Maybe the cables used were not rated for the amps being put through them as well. But to put a hole in the battery, defo something up with the charging.
Re: Melted cables/fire when charging leisure battery from zig
Posted: 16 Jul 2023, 19:17
by Mocki
I agree, the old zigs are not good, nor reliable, and definitely not good for charging lead acid batteries . I would bin it too., but there must be some doubt that it was at fault or it’s internal fuse would have blown, assuming it was correctly fitted
Re: Melted cables/fire when charging leisure battery from zig
Posted: 17 Jul 2023, 18:11
by Brockybwoy
I tried phoning few local auto electricians this morning They 1:said they were really busy 2: don't do campers 3: I'm on holiday (for 3 weeks) and 4: we only do starters and alternators but spent a good 15 minutes giving me some sound advice to troubleshoot fault the to the point where I now feel confident enough to test unit and rewire myself ( and remember go over and buy him a drink) .
I read the zig manual ,referenced wiring diagram ,and visually inspected the unit .Externally everything looks OK no burned components or blown fuses . 240-12v transformer on my cheapo multi meter 25.4 ohms input .6ohms output (Googled to find factory spec but no joy)
I'm going to disconnect burned out battery connections 1-4 and connect old leisure battery direct to terminals 3 &4 with 4mm wire (up from 3.0mm) stock) replace inline fuse (stock 35amp ) with lower 10-15 amp ? and test charge outside of the van .
If everything goes OK I'm planning to rewire with 4mm single core wire , rather than try to find original spec cable that looked a lot like 13A ring main domestic .
Any advice /handy tips regarding routing new cable from behind drivers seat through conduit back to Zig unit would be most most appreciated ( I suspect that a twisted connection around old cable and pulling through (domestic rewiring style) is going to be a lot harder than it sounds with the thick wire )

Re: Melted cables/fire when charging leisure battery from zig
Posted: 25 Jul 2023, 06:13
by SurfT25
Sorry to hear about the wiring but glad you caught it in time
I want to charge my leisure on site but am concerned that doing so would put 240v through my 12v control pannel
I have a high top Caravelle and manage to put my wiring up the B pillar and through roof edge to new control.
Is yours a tin top or pop/high top ?
There are rectangular holes along my roof edge for cab lighting, easier to thread through. But don't know if this is standard or just for Caravelles.
Good luck
As l read my own post it dawned on me that chargers only give out( or supposed to ) enough power to charge 12v not ful 240v .
I take it they are reducers otherwise the thin wires from charger to battery would melt.

Re: Melted cables/fire when charging leisure battery from zig
Posted: 25 Jul 2023, 08:17
by Stesaw
Just to save your sanity, with the wiring make sure it's automotive wiring rather than the stuff youd use in a house. House stuff is a lot less flexible.

Re: Melted cables/fire when charging leisure battery from zig
Posted: 26 Jul 2023, 11:03
by nicklee
[font]Sounds tricky. Luckily it didn't cause too much damage.[/font]