Relay for 12Volt camper fridge
Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=53362
Printed Date: April 19, 2024 at 2:23 AM
Topic: Relay for 12Volt camper fridge
Posted By: Hilux camper
Subject: Relay for 12Volt camper fridge
Date Posted: April 06, 2005 at 12:46 AM
Dear 12volt
I plan to install a relay and wiring from my vehicle battery through to a camper trailer which holds a 12 volt camping fridge. The fridge has two dual deep cycle batteries connected in series, and the plan is to 'charge' these batteries as I drive.
A store assistant recommended 50amp wiring and relay from vehicle to trailer as insurance against burning out wiring should my fridge batteries run flat when I reconnect car and trailer.
As I understand it, once I turn off my ignition, I automatically disconnect car from trailer batteries which is desirable to avoid draining my car battery.
The assistant also recommended I consider installing a solenoid as part of the wiring system. I'm not sure whether this is necessary.
Could you help with a wiring diagram for the relay, and also comment on the solenoid suggestion? If you recommend I install a solenoid, could you also provide a wiring diagram for that too please.
cheers
Replies:
Posted By: ff-mike
Date Posted: April 13, 2005 at 9:11 AM
The relay and the solenoid would be redundant. A continuous duty solenoid would probably be the best, but I think a 30A relay would work fine also. Wiring is going to be pretty easy for this...
Using 30A 'Bosch' relay
30-Car Battery
85-Ground
86-Trigger- from fuse-box, on with ignition
87-to trailer batteries
Posted By: Hilux camper
Date Posted: April 14, 2005 at 6:18 PM
That sounds simple enough even for me!
What is your view about the recommendation I go for 50amp wiring? The existing wiring I have is 15 amp, and I have been advised that I risk burning out wiring if my fridge batteries are dead and my vehicle cranks high amps on start up.
cheers
Posted By: ff-mike
Date Posted: April 15, 2005 at 8:33 AM
#1- deep cycle batteries should not be run down to less than 50% charge.
#2- I don't think you would need to run wiring for 50A.
A good place to go for this information is the RV forums located here
Posted By: Hilux camper
Date Posted: April 17, 2005 at 7:59 PM
Dear FF
Thanks for the tip and the link.
cheers
Posted By: hotwaterwizard
Date Posted: April 28, 2005 at 11:12 PM
Just get a Dual Battery Isolator from the RV place. They are Giant Diodes that Isolate the Batteries from eachother. 
Here is the other way you can do it. 
------------- John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
Posted By: Hilux camper
Date Posted: May 01, 2005 at 7:52 PM
Thanks for the diagram John. I presume it makes no difference that I have my second battery in the trailer, and not in the engine bay?
Posted By: hotwaterwizard
Date Posted: May 01, 2005 at 8:01 PM
As long as the wire is connected the battery will charge.
-------------
John DeRosa (Hotwaterwizard)
Stockton California
When in doubt, try it out !
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