solenoid or relay for caravan wiring

Submitted: Tuesday, Feb 12, 2008 at 19:30
ThreadID: 54507 Views:2164 Replies:5 FollowUps:0
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i am astounded at the wealth of knowledge on this sight.

here is my question , will i need a solinoid or will a relay do for my wireing . what i plan to do is run power to my fridge in my van it will operate when car is on , and off when parked . the power will come via the battery.
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Reply By: Gob & Denny(hampton park vic) - Tuesday, Feb 12, 2008 at 19:48

Tuesday, Feb 12, 2008 at 19:48
gooday zacc
my opinion only but you are probably better off with the solenoid to carry the load
jmo
steve
AnswerID: 287113

Reply By: Mainey (wa) - Tuesday, Feb 12, 2008 at 21:04

Tuesday, Feb 12, 2008 at 21:04
Zacc
so you say when the vehicle is not running there will be NO POWER going to the fridge ??

Mainey . . .
AnswerID: 287136

Reply By: Derek from Affordable Batteries & Radiators - Tuesday, Feb 12, 2008 at 21:18

Tuesday, Feb 12, 2008 at 21:18
Hi Zacc

I would assume it is a 3 way fridge so they draw around 10 amps.

Use either a solenoid or a good quality 30 or 40 amp relay to switch the load.

Make sure the wiring is also heavy enough to carry the load and you use a breaker or fuse on the circuit.

6mm2 cable is recommended.

Regards

Derek.
AnswerID: 287141

Reply By: zacc - Tuesday, Feb 12, 2008 at 21:42

Tuesday, Feb 12, 2008 at 21:42
thanks guys for the advice , much appreciated
AnswerID: 287146

Reply By: BMKal - Wednesday, Feb 13, 2008 at 03:13

Wednesday, Feb 13, 2008 at 03:13
Zacc,

Another option, if you have the room, is to install a second battery in your van (go for a deep cycle). Wire up your fridge directly to this battery.

Then run the wire from your car battery, through an Anderson connector, to the battery on your van. This wire should be controlled through a solenoid. You can get a solenoid that has an inbuilt timer, set so that charge / current is not sent to the second battery for a period of time (usually about 5 - 7 minutes) after the car starts. This allows all of the charge from the alternator to charge the car battery first, before current is drained by your van battery / fridge.

Advantages of this include providing full charge to vehicle battery immediately after starting the car, the fridge will continue to run even when the car is turned off (you can install a separate switch at the second battery if you want to be able to turn power to the fridge off) and the fridge will not be subject to any variations in current / voltage when you are starting the car (one of the easiest ways to damage a fridge).

The solenoid with the inbuilt timer is about $130 - I bought one from Opposite Lock in Kalgoorlie last week as this is the way I am setting up the power for my camper trailer. You can also get much more elaborate set-ups if you want to spend the dollars, including dual battery controllers, charge indicators etc. But for a cheap and safe set-up which provides battery power to your fridge both when the car is running and stopped, and protects your fridge from voltage fluctuation, the set-up I have described above is easy, cheap and works well.

As others have already mentioned, whatever option you choose, make sure that you use appropriately rated cable and decent fuse protection.

When I'm setting up a system like this, I always run two cables - positive and negative. I take the negative cable back directly to the negative terminal on the car battery. If you're already running one cable, it's no more difficult to run two, and the Anderson plug is a dual pin connector. Some people have told me that this is overkill, but I believe that an independent negative or earth circuit in this application is the way to go.

Hope this helps.

Cheers ........... BM
AnswerID: 287187

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