Split charge relay fuse blowing

[meggles]

As title. Can't find answer in the WIKI. I replaced a blown fuse a couple of weeks ago. The earth on the relay was loose so I thought that was probably the cause. Anyway, my son borrowed the van last night and, as I was showing him how everything worked, I found no power in the van. The fuse had blown again I replaced the fuse again but nothing is working still and the fuse did not blow this time . Question: Is there something that could blow the fuse even when everything is switched off and the van isn't being used? BTW, I've replaced the fuse with a lower rated one to err on the side of caution.

[MidLifeCrisis]

Which fuse has blown?

The circuit between the two batteries should be;
starter battery ---> wire ---> fuse#1 ---> wire(a) ---> relay ---> wire(b) ---> fuse#2 ---> wire ---> leisure battery

If one of those fuses is blowing (when the relay is not 'on') then I would assume that the wire on that section of the circuit is shorting to ground somewhere.
So, if fuse#1 is blowing then wire(a) is shorting to ground somewhere.
If fuse#2 is blowing then wire(b) is shorting to ground somewhere.

This may be further complicated by how you have your lights/pumps etc connected to the leisure battery i.e. hopefully these loads are protected by a separate fuse ....

[meggles]

Hi MLC. Thanks for reply. It's a proper autosleeper conversion and not been altered (or I don't think it has). It's the fuse on the relay under the drivers seat. There are seperate fuses for the water pump, fridge, lights etc.

[meggles]

Replaced relay and all is good. (Up to now anyway, I'll see what transpires after a good run out tomorrow).

[CovKid]

If its a simple relay and possibly came with a split charge kit, the relay may be poor quality. The case may be flimsy causing the guts to distort or even short internally. Good solid ones, preferably sealed, are a better bet.

[meggles]

If its a simple relay and possibly came with a split charge kit, the relay may be poor quality. The case may be flimsy causing the guts to distort or even short internally. Good solid ones, preferably sealed, are a better bet.

Plastic, see through, sort of blue in colour if you see what I mean. Been on van since I got it. Replacement is identical.

[California Dreamin]

Did you note down it's power handling (30 amps etc) what fuse are you using?

In theory, down sizing the fuse is prudent, however, as the original split charge systems tend to be a little on the weak side, shall we say, any lower rated fuse may just continuously blow on a partially discharged leisure battery.

Martin

[meggles]

All seems ok now, or it did til I took the engine out. I reckon it was a duff relay. I'll keep an eye on things and if it turns out to be anything else I'll post on here in case it helps someone else.