Battery wiring on Autohomes camper.

[Tweedledubble-U]

My wife has an '84 1.9l water-cooled Autohomes camper.
Yesterday it wouldn't start, it hasn't been used much recently as I've just got it MOT'd for the "summer", so charged battery and all seemed OK.
My wife then went to get petrol 3 miles away and it wouldn't start again. Checked battery and 2 cells dry, changed battery to good charged one then ran engine to make sure there was a charge coming from alternator, voltage was actually less with engine running than with the battery on it's own.
Decided to check all wiring/connections. Removed leisure battery as terminals not in best nick. Then tried to start engine with starter battery, nothing, not even a click although battery fully charged. After reconnecting leisure battery it started fine, disconnected leisure battery while engine was running and it cut out. Reconnected it while ignition was on and the relay next to starter battery clicked into life. So reconnected both batteries, started engine, then disconnected starter battery, engine kept running on leisure battery. It only cuts out when leisure battery is disconnected even though the starter battery is still connected.
The switch to change between the leisure battery and starter battery has no effect on which battery is giving power to engine. So it appears that it is the leisure battery that is acting as the starter battery instead of the actual starter battery under driver's seat.
This cannot be right, the starter battery should be running the engine electrics not the leisure battery. Why does disconnecting the leisure battery stop the engine but doing same with starter battery has no effect.

Puzzled to say the least or am I being a thicko?

[1664]

Oh dear, this might take some sorting

Might as well start with the bleeding obvious. Starter battery under driver's seat, leisure under passenger seat?

I find it hard to believe the leisure battery actually turns the engine over as the size of the cables from the leisure battery are nowhere near big enough (unless the split charge system has been greatly upgraded?).
I think this may provide a clue...

Reconnected it while ignition was on and the relay next to starter battery clicked into life.

This might mean that the relay needs to be energised in order for 12v to supply the ignition system to provide the spark etc that keeps the engine running. It also appears that it has to be energised in order for the engine to be cranked. It may be that the relay is interrupting (directly or indirectly) the 12v to the ignition system and the 12v to the starter solenoid. I doubt it interrupts the 12v to the starter motor itself as it'd have to be a bluddy big relay. I'd trace what wires go to that relay and how they're connected.

Fill in your user profile with your location so we know whereabouts in the country you are.

[Tweedledubble-U]

OK, thanks for reply. Have updated my profile giving location.
Until now all the work I've done on my wife's camper has been the normal mechanical stuff that I'd do on any car I've had.
Just MOT'd it after changing all the springs, replaced front pads and freed off the caliper pistons, changed top ball-joints, replaced rubbers on bottom ball-joints (joints themselves were dirt free), changed exhaust. No problem.
When it comes to the mysteries of the charging/electrical system on the camper I'm heading into the unknown.

To answer your queries, the starter battery is under driver's seat and leisure battery under passenger seat.
The cables connecting the leisure battery are the same thick ones that are on starter battery, they look like the original ones from conversion. So up to the job of starting engine.
On the leisure battery there's the earth cable and the connection to the +ve from starter battery which connects via the switch for changing between leisure and starter batteries when on sites. There is one other less thick (red) wire that is connected to the leisure battery +ve. It is when connecting these 2 wires to leisure battery that the relay clicks when ignition is on. Does the same when they are connected together but not to battery.
The relay itself is a normal headlight type and is connected to +ve on starter battery with earth to chassis. Disconnecting any/all of wires on relay while engine is running has no effect.

Time passes.......................slowly, like my thought process.

I've been writing this reply for hours now as I've been working on the alternator as well. Remedied 2 faults, dud starter battery and an alternator that wasn't charging. Nicked battery from my old Corrado and the regulator from Corrado's alternator. Now have functioning charging/starting system.

Think I have now sussed out what the wiring does on the battery system that has been fitted to this Autohomes camper. Thick cables on leisure battery should have been a clue.
The reason there are thick cables connected to leisure battery is because it is used in parallel along with the supposed starter battery to start engine but the leisure battery should be used on it's own as the leisure battery.
The thinner red wire on +ve terminal of leisure battery could possibly be better connected to +ve terminal of starter battery to avoid non-starting if leisure battery is disconnected. Having a dud battery and a faulty alternator confused the issue (and me ) but now I see how it all works, I think.

Thanks for your help, you made me think of the situation from another angle. If there are any obvious flaws that you can see , but I can't, in what I've written please let me know.

[1664]

Someone had fiddled with / upgraded your leisure battery wiring for a start. Autohomes will have wired it in small cable with about about a 20amp sized fuse. That in itself is not a problem, in fact it's good as a 20amp split charge system is pretty feeble given how discharged the leisure battery gets in this modern day of DVD's, TV's ipads and the like.
The leisure battery should only be connected to the starter battery (and by default the alternator) when the engine is running. This can be achieved either manually with a switch or automatically with a suitably rated relay which switches the connection once the signal wire tells it the engine is running. The leisure battery should not be connected while the engine is cranking to prevent too much strain on the starter battery due to a discharged leisure battery sucking current in tandem with the starter motor. Details in the club wiki here https://club8090.co.uk/wiki/Ca ... it_charger" onclick="window.open(this.href);return false;

You'll probably need to fit a larger rated relay to do justice to the heavier wiring someone has installed and of course fuse it as shown but this will get rid of your current problem and leave you with a more robust split charge system and ensure your camper electrics will only use the leisure battery when the engine is not running without the need for a manual changeover switch. You may find your current relay signal comes straight from your ignition switch. You're just going to have to trace things out or start again as per the wiki diagram. Once you do it though you can label the wires and you'll know where everything goes and exactly how it's wired

[Tweedledubble-U]

Right, thanks for your additional info, much appreciated.

The wiring to the leisure battery does look original to me but maybe someone used proper cables/connectors to alter it, if as you think, it has been altered.

"The leisure battery should only be connected to the starter battery (and by default the alternator) when the engine is running. ......The leisure battery should not be connected while the engine is cranking to prevent too much strain on the starter battery due to a discharged leisure battery sucking current in tandem with the starter motor."

That's what I thought as well, only in the case of my wife's camper it was the dud starter battery that was putting the strain on the leisure battery.
Thanks for the link to wiki page, I had read it when I was looking for info but didn't think it was relevant at the time. Now see that it would be a good idea to do this on wife's camper.

Hopefully get this all fixed and I won't need to do anymore work on it for a while. Wishful thinking, methinks.

In the past few months I've had to remove the interior so that new rear wings could be fitted, repaired all the damage/wear and tear, done to interior since it was new, replaced the interior, plus all the work to MOT it, too. I've done no work recently on rebuilding my Corrado as the campervan was first in queue.

Just remembered what's next on to do list, the Autohomes roof. It has to be one of the worst designed/constructed I've seen.
The standard of workmanship, materials used in the interior and roof are abysmal. Hole in floor for fitting socket for table leg has been done so badly. Hole drilled through plywood (cheapest crap) on floor then larger circular hole, cut right through the metal of body, using a jigsaw with metal-cutting blade. The hole just misses a structural part of chassis, in fact underseal and paint scraped off by blade as it cut hole can clearly be seen on chassis. And breathe, rant over.

[BOXY]

This won't be much help but, my van is an Autohomes Kamper MkII. It will start on either battery and I'm pretty certain all the wiring is as it was fitted in 1982. Maybe a sparkie can check out the circuit diagram below for you?

[Tweedledubble-U]

Thanks for the circuit diagram, will check out to see if it's the same as my wife's Autohomes Kamper from '83/'84.
Although my wife's camper uses both batteries to start, if the leisure battery is disconnected it won't start on starter battery as the thinner red wire needs to be connected to +ve of starter battery by the connecting cable. Will trace all the wires before I do any modifying to rectify what I think, at the moment, is a wrong connection with thinner red wire.

[1664]

Right, according to that diagram the relay is for the 12v operation of the fridge. The relay signal wire comes from the ignition switch so when the ignition is on the fridge is connected to the starter battery (and alternator) which generally is when the engine is running so the alternator supplies the necessary juice for the fridge.

There is no automatic split charge to the leisure battery via a relay however. The 'control unit' (is it the Zig CF6 BOXY?) has a switch which gives you a choice between charging the leisure battery from the 'Mains' ('Mains' sometimes labelled as 'On Site') or 'Car' ('Car' sometimes labelled as 'Touring') or 'OFF'. So if you want the leisure to charge from the alternator when the engine is running the switch has to be in the 'Car' or 'Touring' position. Trouble is if you leave the switch in that position with the engine off both batteries remain connected together and both are running the camper electrics.)

Anyway, I have my starter battery disconnected from the Zig; there's little point having it connected if you have a relay split charge system.

Zig CF6 and CF8 wiring schematic

[BOXY]

The 'control unit' (is it the Zig CF6 BOXY?)

The Zig in my van has got a CF8 sticker on the front but is engraved CF6 under the sticker. I'm not sure what the difference between the two models is.

[1664]

The Zig in my van has got a CF8 sticker on the front but is engraved CF6 under the sticker. I'm not sure what the difference between the two models is.

None as far as I'm aware. I think the CF8 is just the CF6 with a facelift for want of a better description

[brander]

Wiring's a bit of a mystery too but I don't know if the wiring diagrams on p19-21 of this Owners Manual might help?

http://www.autohomes.vwt25camper.info/A ... ismaWM.pdf

Helped me to sort out why my fridge wasn't running on 12v. It was my own fault for not bothering to secure the starter battery clamp which caused the 12v to fridge wire to pull away inside its connector.