Electrical Problem!!!

[richie866]

Hi, wondering if anyone can shed some light on my dilema. I've a 2005 Lunar inspiration which I've owned about 6 months. We had problems when we first got the caravan with the battery, so bought new one (110aH) since then the battery has become flat twice (the caravan is on a long term pitch, connected to the mains all the time.
After trying to get to the route of the problem I've checked the voltage from the psu (13.8v), (by the way the psu is rated at 20A).
I also checked the voltage at the battery terminals with the battery disconnected (5.4v). This was with nothing switched on in the 'van', or so I thought.
I then measured the voltage from the psu while disconnecting the fuses on the 12v board on at a time. The fuse which did make a difference was the fuse for the fridge - when this was removed the voltage then went back up to 13.8v.
The fridge was on, but it was on the 240v setting, so I just don't understand why its taking the power from the 12v circuit.
Could anyone please shed some light on this (Its probably me being a caravaning novice - but I'm more than willing to be educated!)
Thanks in advance

 

[Parksy]

Are all switches definitely off when you leave the caravan Richie?
Our fridge has caught us out a couple of times when the mains lead was unplugged but we'd forgotten to turn the fridge off. The fridge had been on 240v but automatically finds the next power source, the lpg bottle was disconnected so it automatically switched to 12v power. Result - flat leisure battery.
The only other thing that I can think of is the way that the switches are set when you leave the caravan. If 12v or 'car' are inadvertently selected this could cause your fridge to switch to 12v

 

[Dustydog]

Parksy has covered most things. However unless the fridge is set to off, ,the internal light will remain on as long as the door is ajar and over a long period flatten the battery.
Do you have a mover fitted? Unless they are switched off at the isolator switch current is still drawn to the control box.

Let us know how you get on.

 

[Damian]

What is the model number (RM****) and production number (0092********)? Found on data label inside fridge?

 

[Damian]

Prof John L

Online

Joined: 14 Mar 2005

Hello Richie,

I can't be sure but I suspect you may be over chaging the battery, by leaving it under charge when you leave the caravan. , but I do know it will help if you can be a bit more specific about the make and model of the fridge.

Incidentally, with a modern PSU of 20A capability, a battery may not be strictly necessary, unless you are using a lot of 12V appliances at the same time. Perhaps if you were to disconnect the battery , and allow the sites 230VAC supply to feed the necessary items you leave on when you leave the caravan, that may preserve the battery.

Mod Note: This reply moved from duplicate posting...........Damian-Moderator

 

[richie866]

Many thanks for your help guys, I think I am more confused than ever now though!! Like I said I'm new to caravaning, although I'd consider myself pretty hands on and 'with it' in most practical situations, although dc caravan voltage is baffeling me!!

Parksy - All switches are definately off. The fridge is a 3 way fridge - gas, 240 and 12v. It is set on 240. The door is firmly shut, so no light on.

Dusty dog - I do have a motor mover, and I noticed this was connected directly to the battery - I can't find a way to isolate this unless I physically disconnect it.

Damian - I don't know the exact model number of the fridge as I haven't been to the van, although I do have the brochure here and its a Domestic, RM 7272 L to RM 7405 L, I know that covers alot of fridge, don't know if it helps!
Also could you please elaborate about not needing the battery due to a modern 20a psu. As when the battery went flat nothing at all worked.

As I said, many thanks with your help so far, and please be patient with me and my knowledge of caravan electrics!!

 

[Damian]

Yes it does help , knowing it is a 7 series fridge.
They have a permanent 12v supply to power the electronics, otherwise they wil not work at all, that is why you have a draw of power to it.
However, itshould only be drawing a small amount of power , yours seems to be drawing too much which makes me wonder if someone has previously been tinkering and connected the 12v heater element direct via the perm 12v supply.
I would get a mobile engineer to have a look especially if you dont know what you should be looking for.
By that comment I do not mean to be rude, but with the electronic fridges, get it wrong and it is very expensive to replace parts.

 

[richie866]

Thanks Damian - The plot thinckens! When you say the 12v heater element, do you meant the heater element to the fridge?

 

[ChrisUK]

I think a mobile service engineer is called for, and while he is there get him to fit a motor mover isolator. Without one, should there be a fault you might have no way of stopping it!

 

[Damian]

Quote "When you say the 12v heater element, do you meant the heater element to the fridge?"

That is exactly what I mean.
If it has been wired wrongly, it is bypassing the selector switch.

I also have doubts about the state of your battery. at 5.4v it is absolutely dead and would be pretty much impossible to get back to working properly,
At 12v it is flat but recoverable, the lower it goes the harder it is to save it.

 

[richie866]

Damian - Ref the 5.4V - Sorry I worded that wrong! What I meant to say was, when I checked the voltage from the PSU it was reading 13.8, with nothing connected to it i.e straight from the psu and not plugged into the 12v fuses. When I plugged it into the 12v fuses the voltage dropped to 5.4v and by a process of elimination when I removed the fuse to the fridge the voltage then went back to 13.8v. Hope this clarifies things a bit better.

When the battery went flat it was reading about 9v. Although like I said its only 6 months old and a decent 110Ahour battery

 

[ProfJohnL]

Hello Richie,
Your further postings give a strong impression that some unorthodox wiring and installation work has been carried out. Movers without means of isolation, the possibility that the fridge’s 12V element has been wired to the caravan’s internal 12V circuits, it all raises questions which means conventional solutions may not apply here.
Like the others above, this is sounding more like someone’s who doesn’t know what their doing may have been fiddling with the wiring – It needs a competent person to investigate and correct it.
Further to my suggestion that a modern 20A PSU (i.e. post 1994) should be able to run the caravan without a battery. Generally speaking there are very few items that are normally left turned on when a caravan is in storage or not being used. Typically it would be just the alarm systems that are designed to have a very low current demand when just keeping watch. It is perfectly normal for these devices to rely on the caravan’s battery for several weeks before a recharge is necessary.
Alternatively if the caravan is connected to the mains power, then the caravans PSU is quite capable of supplying all the power the alarm needs, and as such it is possible to disconnect the battery. The down side to this is that if the mains power fails for some reason, the alarm will cease to function, and the caravan will not be protected.
It is possible that with a PSU with a 20A output capacity you can run the entire caravan without a battery, but it would need some care in selecting which 12V items are used at the same time – However you do need a battery if you have a motor mover.
Normally and providing the PSU is working correctly it is safe to leave the caravan battery connected, and the mains system switched on. The PSU’s output has been set to prevent overcharging the battery. But until the system has been fully checked non of the above should be tried.

 

[Dustydog]

Prof John said:-
Your further postings give a strong impression that some unorthodox wiring and installation work has been carried out
I saw an episode of Wheeler Dealers the other night where an unknown previous owner had bypassed the radiator electric cooling fan with a dash board mounted on / off switch. A new temperature sensor was only a few pounds!!

He must have had his eyes glued to the temp guage.
Amazing some of the weird mods people do to save a few pennies.

 

[richie866]

Prof John - Many thanks, your comments ref the psu have been enlightning and educational. As I may have said before I consider myself fairly switched on when it comes to practical 'stuff' but I reckon 12v DC caravans circuits have beaten me - or have they!!!