backup light wiring question - is a relay really necessary?

[TomGolden]

Hi all,



I am going to be adding some aftermarket cargo/backup lights to my Ram. I know a lot of people use relays when they wire such

things, and the pusher pump kit I got also came with one, which I used.



Now my understanding of a relays function is to act as a switch, and also as a circuit breaker/fuse. Is that correct?



Basically, where I'm headed with this question, is a relay really necessary in my specific circumstances for these lights, or is it just

redundancy. For the power, I already have 2 of the Painless Wiring kits I got from Genos Garage, and they are all 30A fused

connections. I will be using one of these connections, going to a toggle switch in the cab for these lights.



So, in view of that, would a relay really add anything for me, or would it just be overkill?



Thanks all,

Tom

 

[jerryrigg]

The function of a relay in these cases is not to act as a switch but to take the load (current) of a switch. You did not say if you are planning to wire the lights to the existing backup lights or a separate switch. If you are wiring them to the existing lights then Yes use a relay. Wire it so the backup lights energize the relay and feed fused power through the relay to the lights. You may or may not want the power to be "keyed" power, if not then you can turn the lights on without the key. If you are running them from a separate switch then you need to ensure the switch can handle the current load of the lights, and the wire is large enough to handle the current based on length of the wires, I'd go with 10ga myself.



-Matt

 

[HTRDHLR]

I did mine with a relay but i have had a problem with the relay sticking on. I think I need a special weatherproof relay. Anyone know where to buy??

 

[redeye]

I used a relay triggered by the existing backup lights. Placed it up behind the drivers side tail light well protected from the elements. Ran 10/4 SJO cord (spare wire for future) from the engine compartment through the frame rail to the back of the truck fused at 30amps with a dedicated ground. The lights are 150 watt rectangular tractor type floods at 12volts that’s a little over 10 amps each, way to much for the stock wiring.



What a difference, no problem seeing now tinted windows or not.

 

[Dane]

These guys have very good relays of all sizes. Thanks to another TDR member for the tip.



http://waytekwire.com/



They have lots of other electrical stuff too...

 

[wlowe]

Using a relay is the only way to go, reduces the chance of overloading a circuit or switch. Check this site out for more info:



http://dodgeram.org/tech/mods/



Bill

 

[RKohn]

Plug into the trailer receptacle...

unplug when you go to tow. Unless you wanna see the front of the trailer real well.

 

[Josparkz]

I added a couple of par 36 tractor lights to my bumper , the little ones. I think that they are 35 watts @ . I looked at the wiring diagrams to see what size wire and what the wattage of the OEM lights were . I calculated that the wire shown on the diagram was sufficient for the additional lights. I verified that the wire gauge was as specified . It was.

To keep it simple , I just paralleled the lights with the other ones.

Works for me.