spanky1989

Does anyone know where I can find what amperage an led offroad light/led bar/ spots and such draw? Working on my own version of a relay box and I'm looking into using the smaller relays that can handle 10/20 amps. I have a feeling that I'll be ok doing 2 lights per circuit but want to be sure before I get too far into it. Thanks for any info or advice.

spanky1989

Here is the relay style I'm looking to use.

JTB488

It should be on their site. All depends on which one's you pick. Small cubes vs 50 inch bar. I have some small Rigids and Cubes from Inspired Eng and they draw less than 2 amps.

Vladimer

It all depends on the size of lights you have.

Here is a handy converter - Volts/Amps/Watts Converter

14Sport

Amps = Watts divided by Volts. (A=W/V).

So if you know the watts of the lights, you can easily calculate amps.

For example, a 55W light would draw 4.58 (55/12) amps. A pair of them would draw 9.17 amps.

Things to keep in mind:

1. Many lights come in pairs so you have to use the combined amps if they are running off the same relay.

2. Generally you want a relay that is rated around 20-25% higher than the draw.

3. The alternator puts out greater than 12 volts. However, I always use 12V in my calculations (many use 13.8V) because it gives a built in safety factor.

So for me, the most I would run on a 20A relay is 16A (20A x .8).

Based on that, the maximum wattage for lights on a 20A relay would be 192W (16A x 12V), again for me.

If you use 13.8V in your calculations, then it would be 221W.

spanky1989

Thanks for the feedback. I already new about the math to find current, I just wasn't sure if it was the same for an led. Many LEDs put out a higher wattage of light than the standard bulb, so I thought there might be a different formula. I guess I'll just have to look into which lights I want to go with and go from there. Thanks

spanky1989

It would also be nice if I could get my amp meter attachment to work on my meter.

stagedtrip

10 characters

14Sport

You're on the right track, but it's lumens not watts that are different. The LED uses much less wattage (approximately 1/4) to produce the equivalent lumens of halogens. So a 10W LED will produce the equivalent light (lumens) as a 40W halogen. A 40W halogen will draw 3.33A (40/12) while a 10W LED will draw .83A (10/12) to produce the same amount of light. But whatever the watts are still determines the draw, with voltage of course.

spanky1989

Oh ok that makes sense, so the average 55w led will be equivalent to a 200 something watt halogen. From what I'm gathering I should be alright with the 10/20 amp fuses for led lights. I'll obviously use the regular size relay spot for onboard air when I get to it. Anyone have any opinions on what kind or relay control wiring to use from the switches? I was thinking about the cat5 cable route.