Club 80-90 Forums

I have an '88 Autohomes kamper which has a leisure battery fitted under the front passenger seat. It does not have a Zig unit fitted but is wired into a cigarette sized black box also under the passenger seat. This box has 11 inputs but only 6 are wired and run to to both batteries and into the van's electrics. The is a spade type fuse in line with the positive of 15 amps but this keeps blowing. Is this the correct rating as fitted by the previous owner? Does anyone have a wiring diagram with the colours correct or did Autohomes vary the wiring dependent on what they had available?
Many thanks in advance.

Doesn't sound vey 'Autohomesey' to me. Any chance of some pictures? Can you gain access to the internals of your 'black box'?

As Bren says^^^^ a picture would be good.
Best guess at this stage would be some sort of split charge relay.
Devices like this usually have a scematic diagram or wiring 'key' etched onto the casing or at least....wires that have labels? perhaps you could post back with this info....
If it is a split charge relay then 15 amps as a fuse is very low but then, at this point we don't know the rating of the device.
Typically, basic split charge wiring is fused around 25 - 30 amps but be aware that you never rate the fuse above the capabilities of the wiring.
If you were doing this from scratch I would suggest looking at something even heavier duty than this (70 amp relay...50 amp wiring, 40 amp fuse) as a start.

Martin

Sounds like a twin relay with only one bank used to me. As Martin says, a meaty relay a good idea although who knows, that one could be more than man enough. See what markings are on it and we'll guide you a bit more.

Is it similar to this?

I agree, it doesn't look very Autohomes-ish and doesn't agree with any of the wiring diagrams that I have found. I've attached a photo. Ignore the in-line fuse as I have added that for a cigarette lighter to charge phones etc. The 15A one is top left on the green wire (I know it is the wrong colour for 15A but now have a 20A as run out of 15A ones). There are no markings on the black box top left.
Thanks

Looks like a relay..... I can't see what wires go where, are there any markings on the terminals? Measure your leisure battery voltage; could be the battery is drained to a point the recharging current is more than the fuse can handle.

Does the 20amp fuse blow or is it hanging on in there (with engine running)? I wouldn't chance going bigger than 20 amp mind.

That looks like a W4 combi master split charge relay. They do or did two types a voltage sensing and a normal one, can't see from the pics which one it is but you need to check it's wired correctly and a 15A fuse between the two batteries will blow if the leisure battery is flat.

Voltage sensing
http://www.w4limited.com/pdf/10005_Instruction.pdf" onclick="window.open(this.href);return false;

Normal
http://www.w4limited.com/pdf/10004_Instruction.pdf" onclick="window.open(this.href);return false;

bigherb wrote: a 15A fuse between the two batteries will blow if the leisure battery is flat.

Agreed with Herb and the others, a flat leisure battery can take 45 Amps or more for the first couple of minutes.

In my opinion the wires that links the batteries, via the relay, should be heavier then what yours appear to be (in the pics) and a 45 Amp fuse (In a suitable rated holder) can then safely be used (mine is 60 Amp by the way).

p.s. - I note there is a green wire from the +ve going directly to the relay (no fuse) - I wonder where that goes (after the relay contacts) ?

p.p.s. = Which is the wire that comes from the main battery in that pic ?

Was wondering that myself