Continous 12v for replacement fridge? (1 Viewer)

[John Turnbull]

Hi folks,

I have a 2003 Sundance 530S. The original fridge, an Electrolux, just packed up and I have replaced it with a Thetford. The problem is that the Electrolux had mechanical switchery and the Thetford has electronic. The 12v supply for the electronics is the one that turns off when the engine starts so although it has the heavy duty 12v to keep it cool, it cannot be turned on while driving. Thetford, anticipating this problem, has provided a bed for 6 u2 batteries to run the switchery so I can in fact get 12v cooling while driving. Unfortunately the 6 U2 batteries only last a few days which is a real pain.

Has anyone found a way to get permanent 12v to the fridge compartment?
.

 

[Minxy]

Hi JT - welcome to the fun house!

If the original fridge was a 3 way then surely you should just be able to use the existing 12v connection from that? I thought the battery back-up was just for when you needed to use it on gas and didn't have any power to the electronic controls, not to actually run it?

 

[John Turnbull]

There are two 12v supplies to the fridge. The heavy duty which does the cooling turns off when the engine stops and the low power (for the internal light in the old Electrolux) turns off when the engine starts. There is no permanent 12v supply!

^{_{Subscribers  do not see these advertisements}}

 

[DP+JAY]

Yes that's a quirk of british vans, the habitation 12v turns off when the engine starts.There is a way to overcome it & there will be a thread on here somewhere.


Here it is.

http://www.motorhomefun.co.uk/forum...ea-whilst-engine-running.119799/#post-1641174

 

[John Turnbull]

Thank you very much!

 

[Minxy]

Ah, I see, you may need some sort of relay to work on both inputs ...

^{_{Subscribers  do not see these advertisements}}

 

[mariner]

You need 3 x 12v connections for a AES fridge to work properly!

 

[Minxy]

Info on page 13 & 14 of the below:

http://www2.dometic.com/35569465-a189-499b-b3a4-e5f8beb18c67.fodoc

It appears you need to take a lead from the leisure battery itself to the fridge control:

connection marked “Connect to permanent 12 volt DC House Battery” (RM2355/RM2455/RM2555) or “12V DC House” (RM4605/RM4805) This connection supplies the AES refrigerator control system and must not be interrupted at any time whilst using the refrigerator on 240 volt, gas, and 12 volt. This is a permanent 12 volt connection. The (+12V) and (-) poles have to be connected directly to the permanent 12V DC house battery. Do not use the chassis for the return lead. The 12V supply must not be connected to a voltage controller or similar device as the AES control system itself monitors the DC voltage. The +12V must be permanently attached and must not be cut out when the ignition key is turned off. All connections should be screwed or soldered to keep voltage drop to a minimum.​