Unknown switch

Hello,
On the outside lower panel of the passenger seat there is a switch. (1994 Clubman GL). Can someone tell me what it is for?

It may be for the battery charger for the 12v habitation battery. That is housed under the passenger seat. 

By the way, Croeso / Welcome to the Forum. There are half a dozen or so of us in Cardiff.

Cymro

Thanks, Cymro, and thanks for the welcome.
That seems very likely. I have usually used a hook-up, and have never looked into the functionality of the leisure battery and its circuitry. I'll get my meter out and look into it tomorrow (when it stops raining!!). Thanks again.
Moel

My 1998 Clubman had the leisure battery charger under the passenger seat; it had an illuminated on / off button, facing forwards, visible from the footwell.

Maybe someone re-wired yours to move the switch to the side. Or it could be a master switch for the 12v - though mine was on the panel forward of the drinks cupboard and fridge I think, just above the bench. Useful for turning off the 12v lights without getting out of bed.

Cymro

Yes, it is simply the Zig X-3 battery charger switch. I assume this should be off when not connected to the mains, or the battery could be discharged through the charger circuit.
I hope it's OK to ask another question. I have replaced the internal halogen lamps with LEDs. I would like to extend the 12v run time when not hooked up, and am thinking of buying some extra leisure batteries. Would the Zig be able to cope with extra batteries in parallel, or should I install an extra charger on a completely different circuit, with a suitable switch over.
I would imagine this has been discussed many times. A link to this topic would be much appreciated.
Moel

moel wrote:I assume this should be off when not connected to the mains, or the battery could be discharged through the charger circuit.

Provided the Zig charger is working Ok, there will be a small discharge back through the charging circuit while it is unpowered, but the effect should be tiny. We have owned several vans with Zig chargers and leaving it switched on never caused us any issues.

Hi

Roopert wrote:Provided the Zig charger is working Ok, there will be a small discharge back through the charging circuit while it is unpowered, but the effect should be tiny. We have owned several vans with Zig chargers and leaving it switched on never caused us any issues.

Agreed, the back current into the Zig is so small you can ignore it. I just leave mine on all the time.

moel wrote:I would like to extend the 12v run time when not hooked up, and am thinking of buying some extra leisure batteries. Would the Zig be able to cope with extra batteries in parallel, or should I install an extra charger on a completely different circuit, with a suitable switch over.

The Zig will cope with any number of batteries - no upper limit but it will take longer to charge.

OK it’s called a charger but its main function is as a power supply i.e. supplying the current you use in the van while on hook up and keeping the batteries topped up at the same time. The Zig is not a very efficient charger anyway but that’s not a problem because it’s rarely called on to charge batteries from scratch. The main charging device is the alternator.

The output from the X3 is a bit low by modern standards but it may well be all you need so why not see how you get on? In any case there is no need to fit a second charger. Modern drop in replacements with a higher output are available:

https://www.rainbow-conversions.co.uk/charging-distribution/zig-x70-leisure-battery-charger-309-p.html

https://www.pioneer-leisure.co.uk/Caravan-and-Motorhome-Battery-Chargers-and-Inverters/ZIG-X80-charger-caravan-or-motorcaravan-battery-charger

If you fit a much higher output charger you’ll also need to check and possibly up rate the wiring. Remember that the total current (worse case) will be the charger output + the leisure battery supply which is usually fused at around 20A

If you you think you are going to use the 12V electrics heavily why not consider adding solar to the mix (lots of threads on that).

Brod

Thanks, Brod. A very useful answer. I am still a bit unsure of the role of the alternator. I had assumed that it only charges the vehicle battery, not the leisure battery. Am I wrong?

It does seem that Solar is the way to go in the long term. I shall look into it.

Thanks,

Moel

On a van of that age, the alternator will charge both vehicle and leisure batteries via the split charge circuit.

In terms of cabling, one other possibility if you have more than one leisure battery is that the split charge circuit fuse(s) may be more inclined to blow when starting the engine while the leisure batteries are at a low state of charge.

If so, the only proper way to address it would be to uprate the cabling and fuses together. You should not uprate the fuses on their own without changing the cables, as the fuses are there to protect the cabling.

Now that is extremely interesting. If the alternator charges both batteries, then it is unlikely that I would get a problem with the 12v appliances, the leisure battery being topped up on journeys.

There will be no need to make any modifications/improvements. It will be sufficient to get a new leisure battery. The old one has been there a long time, at least 10 years!

I asked Autosleepers about all this back in the days when that was possible. They assured me that the interior electrics were isolated from the vehicle electrics. Perhaps that is true of newer models only.

The only way to make sure is to measure the voltage on the leisure battery before and after a long journey. I hope you are correct (for my particular vehicle). If so, you have saved me a lot of effort. Many thanks indeed.

Moel

It's certainly a test that is worth doing, especially on a van that has been bought recently. It's quite common for leisure batteries to go flat while on a dealer's forecourt, because prospective buyers switch things on and sometimes forget to turn them off. Then the next time the engine is started the split charge fuse blows - but the dealer is unlikely to notice.

I don't think any A/S conversions would have been made in '94 that had a leisure battery but did not have a split charge circuit, though IIRC a mains charger might have been optional.

Very useful again, Roopert. I have had the van 10 years. The effectiveness of the 12v circuitry has never mattered in the past, but I want to get out into dark locations to do some astrophotography. There are plenty of campsites in mid Wales that would be suitable but for the  security lights! 

I will see if the leisure battery gets charged when it is possible to buy petrol again. If it doesn't, I will try to locate the split charge fuse.

Once again, thanks for pointing me in useful directions.
Moel

Hi

moel wrote:I am still a bit unsure of the role of the alternator. I had assumed that it only charges the vehicle battery, not the leisure battery. Am I wrong?

If it helps, here is a basic explanation of how the system works:

https://drive.google.com/file/d/1gYe0vun6vWh0Dwb6w_0TNcQLR4hDvqdn/view?usp=sharing

It’s specific to the “97” Duetto but although there may be minor differences the wiring system was similar for all AS models of the era, don’t worry about the copyright notice, It’s only to control use by publishers. You (and any member of the forum) have full permission to download and copy it.

My van has no fuses between the two batteries. Not a great problem normally because the wiring is heavy enough to carry the full alternator output. It could be a problem if there is a short circuit on the alternator side (unlikely) but at least I’ll know by the smoke.

The habitation relay may or may not be fitted. It became a legal requirement somewhere around 1996 as a safety feature to stop electrical interference from the habitation area affecting the vehicle electronics. A problem on later vans but earlier van didn’t have much in the way of electronics to be interfered with.

Brod

I am sure I replied. Anyway, thanks to all of you for your help. The alternator does indeed charge both batteries.

Brodco's link was extremely useful, much clearer than the Zig user manual. So whatever fuses are on the schematic, they either work or don't exist. There is no reason why the electrics shouldn't last for another 27 years! 

Thanks again,

 Moel

The sort of problems that arise particularly after some time tends to be issues with fuse receptacles and relay terminals. If you tend to run for some time off EHU when you then start the engine the split charge relay will activate linking the Starter and Leisure batteries. So for a short time a fairly high current will flow between the two until the battery voltages equalise hence the recommended 20A fuse. The fuse may not blow but corrosion resistance in the connector will result in heat.

With a vehicle of this age it is worthwhile inspecting these parts for any signs of damage. I lost my 12v off hook but all fuses looked good however refitting the Habitation fuse I noticed a faint arc flash inside the fuse body. The fusible link sometimes has a pinch point which sets the fuse value and mine had cracked at that point.


Also note that the Habitation relay is ON when there is no power to the coil. This relay is a 5 terminal relay not the more common 4 terminal type, this is because it has a Normally Open contact and a Normally Closed one