In preparation for installing my kc lights, I was going over the instructions from the KC website. They have two different methods, one using a relay and one without a relay. What are the advantages/disadvantages of using the relay.

 

Use the relay. Sure, it's one more part to fail, but it gives you the ability to control the power better, and negates the need to run a heavy-duty wire to carry 30A into the cab and back out to the lights, which reduces the voltage drop through the wiring and increases (marginally) the intensity of the light.

Basically the relay allows you to use a very small amount of power to control a large amount of power. I always prefer that way for any high power items.

-Joe

 

Use the relay. It provides extra protection, so you don't have to have a bunch of amperage going through a small switch. It will cost about $5.00 more, but be a whole lot safer.

 

yup definatley a relay... better then running without... like ^ said.

 

Will a 10 amp switch be sufficient for a set of 100 watt lights?

 

depends on whether or not you're using the relay... with the relay, you can use any kind of switch you want, so long as it can carry 0.3A per relay you're triggering. Without a relay, no, it will not work.

I=P/V gives you:

the current (A) = 200 watts /12 volts = 16.7A.

Now, if you were using one switch per light, yes they would work, but who does that??

-Joe

 

As others have already said, use the relay. If nothing else its a safer set up. I've never trusted switches that claim 20-30 amps, I just don't see it working. Remember, if your using a relay, your switch really only has to be able to carry a few watts, just enough to say to the relay, "Ok, send the electricity through to lights!" as the relay is then acting as the "door" that keeps electricity from going to the lights, and the switch is just the ****.

 

That's a pretty good analogy. I actually tested mine to see how much current it took to trigger the solenoid, and it was less than 0.3A. The less juice I have running through the cab, the better. That's why I was able to get away with $2 mini-toggle switches in my truck. Pics are in my gallery under "accessories".

The other advantage of running the relay is less wire length between the power source and the lights, which means less resistance, which means less voltage drop between the battery and the lights which means brighter lights.

-Joe