Dometic fridge installation

Submitted: Friday, Apr 27, 2012 at 15:07

ThreadID: 95186 Views:2251 Replies:4 FollowUps:1

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mac3

Hi all, I just bought a second hand Dometic RM2455 to replace the old 60litre one in my old caravan. I downloaded the install instructions and it talks about wiring up the house battery and the vehicle battery separately as the brains need a permanent 12v to run all modes. I'm not quite clear on this-

For a Motor Home the house battery and the
vehicle battery may be the same battery.
• For a caravan the 12 volt connections can only
be made to separate batteries.

When you're parked with 240v does this mean over a period of time your house battery will go flat? (I don't have a permanent charger) I do have a 20 amp 12v power supply which I run the tv, stereo etc on, could I hook up to that? Although it says to fit a 20A fuse, seems a bit over the top to run electronics.
Thanks in advance
David

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Reply By: The Bantam - Friday, Apr 27, 2012 at 17:16

Friday, Apr 27, 2012 at 17:16

The 20 amp fuse is because of the high current drain when its running on 12 volts alone...it draws 175 watts on 12 volts according to my cursory reading.

If the 240V fails it will revert to operation on 12 volts

It probably needs a 12 volt supply because its automatic and it needs something to think on.

AND yes if you are parked up ya 12 volt battery will go flat over time.

If the supply you are using has a terminal voltage of 13.5 -13.8 volts it will be fine.....leave that float chargiging ya battery and run ya telly and stereo of the battery..any not consumed by the telly and stereo will go into the battery.

cheers

AnswerID: 484393

Reply By: Nomadic Navara - Friday, Apr 27, 2012 at 21:42

Friday, Apr 27, 2012 at 21:42

Your fridge is an AES (automatic energy selection) type. It contains a control board that requires a constant 12 V supply (at very low current) to operate. This is connected to your house battery. It also requires a large 12 V supply to run the 12 V element. This is connected to the hot wire from your tugs battery.

If you have all three energy sources toe board will select the 240 V supply in preference to the others. When the 240 V supply fails the fridge will be switched to 12 V operation. If that also fails, the gas will light up 20 minutes later (the time delay is there so the gas does not light up when you drive in to fuel the tug.)

PeterD
Retired radio and electronics technician

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AnswerID: 484405

Reply By: mac3 - Sunday, Apr 29, 2012 at 20:26

Sunday, Apr 29, 2012 at 20:26

Thanks guys, looks like I was on the right track. Thank you for your confirmation.
cheers
David

AnswerID: 484567

Reply By: oldtrack123 - Monday, Apr 30, 2012 at 10:13

Monday, Apr 30, 2012 at 10:13

Hi David
From your question I assume you do only have one set of batteries

In that situation it is ok to run a heavy pos & neg feed to the main 12v input& loop with a lighter cables to the 12v control terminals
BUT it is essential that you connect the D+ terminal of the fridge to the D+ from the alternator
Failure to do this correctly could lead to a flat battery

Peter

AnswerID: 484606