Melted cables/fire when charging leisure battery from zig

[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

 

[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 ?

[Oldiebut goodie]

Battery connections were reversed somehow?

[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 
 

[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.

[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

[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 ) 

[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.

[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.

[nicklee]

[font]Sounds tricky. Luckily it didn't cause too much damage.[/font]