Wiring woes

G'day all,
I have installed a Redarc DCBC and got it all working!

But from time to time the circuit breaker near the feeder battery is tripping. When reset everything works fine and the tub battery is getting charge.

I assume that the issue is in the wiring from the main battery to the redarc, or the redarc itself.
Is it likely to be a rub-through somewhere?
I used the heavy wiring 4awg or something, thick as your finger, and it's in the corro plastic except where it comes through into the tub behind the tail-light through the panel gap.

I have partially removed that and it looked intact.

Looks like I will have to drill and grommet the tub and re-run the power cable.
Hopefully it's not the charger- it threw codes once but stopped before I could decipher it and hasn't repeated.

Redarc is earthed to the tub- could that be the issue? Might change that first?

Suggestions needed please

If u have a multimeter disconnect both positive terminals, check if there is any resistance in the line. If that's ok put the red probe on your earth and the black to a good chassis earth, you should have 0v there. If they both check out ok it's time to have a really good look at the wiring, even if there is a small nick in the wiring insulation it will cause an intermittent short. Try those and see how u go
Cheers Deano

What rating is the circuit breaker?

The earth shouldn't cause that issue, but I'd be moving it to the chassis. Alternatively, put a nice fat cable or 2 on the underside of the tub to the chassis and that will fix any earthing problems.

As for the problem, it could be the wiring through the tail light area. It probably wouldn't hurt to drill it and either put a grommet or cable gland in there, just to avoid any problems of it rubbing through.

It's a 40 amp breaker.

I will be adding an earth from the tub frame to the chassis this weekend.

I know I have to do the tail light drill through, but it means pulling out all the fridge slide and battery box and I am trying to avoid it.
Ah well, see what Saturday brings.
Thanks to all

Thermal breakers work by heat. When current passes through a bimetal strip, the strip heats up. When it heats up enough - usually somewhere around (or marginally over) the rating of the breaker - the strip flexes and the breaker "trips". When it cools, it resets itself.

The problem with thermal breakers in an engine bay is extra heat. Particularly on the exhaust side, but the majority of the engine bay is going to be quite warm anyway. A 40A breaker can handle 40A at a set temperature (I think the standard is 25C when it's measured). If yours is sitting in 80C air, it will trip that much sooner. How about shielding it?

I'd also check the resistance after disconnecting the cable - you might find that it's snagged something underneath and it's always worth being careful.

Earthing to the tub? I doubt it'll trip the breaker, because if there's a dodgy connection it will stop the power from flowing, not increase it. That said, it's something that I don't (won't) do myself. I have a pair of 8Ga cables heading to the rear for a total of 112A capacity. Those cables are twins - I run both positive and negative. This avoids issues.

I had run the cable to the tub from the left battery just to share the burden since everything else hangs off the driver side battery.
So the breaker is in the engine bay between the air box and the fuel filter, then the cabling runs across the firewall and down the right side to avoid exhaust exposure.

Looks like I might disconnect and attach to drivers side battery as that side will be cooler?

Edit- what would you suggest I shield the breaker with?

I used all the foil for my hat to keep the aliens away

Aluminium isn't bad, but simply mounting it behind the headlight will help. The battery will help shield it.

See how it goes after adding the earth. It may solve your problems. I do prefer the method of positive and negative wire to the charger.

As Tony mentioned they are a bi-metallic strip and once they do get hot several times, it does have an effect on them and can trip out at less than the rated current.

Tappet said:

See how it goes after adding the earth. It may solve your problems. I do prefer the method of positive and negative wire to the charger. As Tony mentioned they are a bi-metallic strip and once they do get hot several times, it does have an effect on them and can trip out at less than the rated current.

Click to expand...

Thanks Tappet, I have an identical one in the tub between the redarc and tub battery, so will swap them over when I move it and see if that has an impact.
Thanks Tony and others as well!

G'day

I have removed the entire power line between batteries, and there is not a mark on it. Bugger.

Had to cut the anderson plug off to get the line out of the tub, but have now drilled through and grommets are in.

So it's either
The 40amp breaker is cooked (it was behind the air box)
The earthing is a problem (which I doubt)
The redarc has shit itself.

So question time!
I have to earth the redarc and the tub battery - can I attach them to a bus bar and run a single cable out of the tub?
The 40 amp breaker is for car audio systems with a manual reset and matches up to the cabling 4awg I think- but it's plastic - is that an issue?

I am going to get more 4awg cable and run the earth back to the feeder battery just to eliminate that altogether.

I must get there eventually!
Bernie