Car/Van switch, when to have it in what position?

As some of the regular members have no doubt already discovered, I'm a bit of a noob when it comes to camper/motorhome systems!

I have a main switch in the van.  In this picture all the switches are set to what I'd call the off position apart from the main on/off switch, which is on.



As I understand it, this switches from using the car battery, to the leisure battery, but I have a couple of questions about the car/van switch:

1. When should I use which?  Should it be in the off position (van, as it is in the photo) pretty much always, unless I need emergency power from the car battery because the leisure battery is dead?
   
   
2. Should it be on car if I'm driving?  I do have a fridge in the van which I think can be used when the engine is running?  I don't need the fridge anyway, so I've left that alone and I think on the fridge itself it's just set to be off.
   
   
3. If I'm connected to mains hookup, I'm guessing I want the main switch to on, and the car/van switch in the van position to charge the leisure battery?
   
   
4. If the car/van switch is set to car, does it charge the car battery instead of the leisure battery when hooked up?
   

Anyone have any manuals or anything? (I looked but I didn't find anything).  Sorry for the basic questions, but it's been very hard to find information using such generic keywords!

1: I think you should keep it in the "van" position so it will (probably) just use the leisure battery. Just use car only when you need the power and the leisure battery doesn't have it anymore. But if the volt meter goes to low you won't be able to start. So don't use it if you don't need it.

2 & 4 (charging/driving): I don't think the charging is being done over this panel. Because this is all typically 15Amp stuff at max and would be destroyed by charging over such a switch with a 70Amp or 100Amp alternator.
So very likely the first battery is charged as in any car, and you have to check how the second battery is charged. There should be some kind of automatic relay or diode box with thick cables. You should follow big cables going from you starter battery to the second battery. And then send us a pic of the box that is between the big wires.

2 (fridge): Check your fridge brand and type. If it is a fridge that can run on gas and electricity, it is probably not so efficient and you can only use it will driving.
If it is a fridge that only runs on electricity and you can clearly hear it running when turned on, it might be a compressor fridge. And a compressor fridge is an efficient fridge which you can run fine on the leisure battery. I have such a compressor fridge and it is excellent, I can run it for ages on the solar panel and leisure battery.

3: Mains hookup is connected to 110v/230v power of campsite or something else?
Then yeah, the main switch should still be on because it will still control your electronics like always.
As for the charging, again it is the question how the charging is hooked up. Where your AC power cord is coming into the van, follow the wires. There is probably some charger box, and it might be connected directly to your leisure battery (is what I would expect). If that is the case, then you can not control charging of the AC power to which battery.

Manuals and stuff is hard to say, you would have to look it up for the products that have been used in your van.

Hey man, thanks for your replies.

1. I'll keep it on van then. I wasn't planning on using the car battery for anything except the car. Although it wouldn't be the end of the world - I have a lithium ion battery pack that jump starts my van from cold, without the battery even being disconnected! I started the van 3 times and the battery indicator didn't even go down! Even so, I won't be using the car battery.

2 & 4 - That makes sense, I hadn't thought of the power going through the switch! Obviously that's not happening, and now you mention it, I'm pretty sure these shore power hookup points charge directly into the leisure battery. As for charging while driving, I do vaguely remember the owner saying something about the leisure batteries being charged when driving, I just don't remember what as I had so much new information at the time!

2. Fridge is an electrolux RM 2262, which is a 3 way fridge - gas, 12v and mains. Takes about 0.25 kg per 24 hours according to the manual, so on the off chance I do need to use the fridge - the big 12kg gas bottle I have will do the trick!

3. Mains is currently connected by the standard 230V hookup to the van, then I have an adaptor I bought off ebay, that connects to the hookup and plugs into a standard plug socket.