Battery Problems

Not much to go on here, DH. 

Is this while stored or in use? If stored it seems likely the 12v is being left on and something is plugged into a 12v outlet causing discharge of the battery, Check out what fuse 3 is in han!dbook. Could be 12v socket.

Check basics first, hope this helps

If three batteries have been discharged that quickly then there is something wrong as nothing should do that so quickly.

Not sure what fuse three is on your caravan, on mine the fuses are labelled but it might indicate a short circuit which could be the problem. I would hope the handbook details what it is. I would remove the fuse and see if the problem persists but whatever take it back to the dealer to correct.

If it persists have you isolated everything. I do not have your model of caravan but assume it has the same fuse box as ours and there are three buttons on top. The black one should isolate everything except an alarm if you have one. I would use that if you have not done this and see if it helps.

An alarm will probably still use power but would not run the battery down that quickly. Two weeks is more the norm for that.

You might also check that a motor mover, if fitted, is isolated, but if it is wired correctly again it should not be that drastic if left on.

Hope this helps but I think a visit to the dealer to correct the problem may be needed.

Not sure of anything that would discharge it that quickly. What size battery is it? 

I guess the other question is does it still discharge if fuse 3 is removed? If the answer is no then there must be a short circuit on that circuit.   As it a 2018 van I would get back to your dealer and get them to trace and fix.  

If there is a fault that is running a battery down in a few hours I would also be concerned about the amount of heat generated and the potential risk from that.  

I suspect there is a short on a 12v outlet somewhere, is it a 10A fuse blown? Can't find a 2018 manual on the web but on a 2019 model fuse 3 is 12v sockets.

Buy something like this   Tester   Remove each fuse in turn and connect the tester, any high current draw (with everything off) on the fuse holder being tested will show you what circuit (if any) is at fault.  The one in the link is rated at 20 amps so should be robust enough. 

Went into caravan other day and it smelt of rotten eggs....

Checked battery, and yes it was very hot. Bought new one and fitted this morning.

My question is, I always have left electric connection on the 'van when parked outside of house, naturally still with battery connected. Have done this for over 30 years with no problems. Should I continue to do so....? What do others do?

Could be the charger is at fault and it cooked the battery you just replaced ?  I'd keep a close eye on things for the next couple days personally.

Definitely not. If you have an intelligent charger then you might be OK but if you have a conventional charger you will reduce the life of the battery. Either way you should not leave the van hooked-up. You will find this advice within the Club’s information, in your manual or other sources.

I would disconnect as I think the charger must be overcharging the battery which would explain why it is hot. Sounds like a faulty charger as I assume you will have one that should prevent this but do not know the spec. My approach would be to ask the dealer if the charger has the appropriate protection before telling him about your problem and if he says yes then ask him to replace it as it is faulty.