KC 8" HID lights current draw

[Taxman]

I also posted this in the sticky that discusses the connection to the Aux switches. Mods feel free to merge or remove one or the other.

So I bought two pairs of the KC 8" ProSport HID lights and I followed the instructions in the sticky for Aux switches. I computed the current draw and since the HID lights are 35w each and there are four of them, I figured 140W divided by voltage of 14.4V equals about 10 amps of current draw for all four, so I wired all four to Aux #3 and blew the fuse as soon I turned them on. What gives? Do I have a short somewhere or is it just too much current draw? Where did I go wrong on my computation of current draw?

Thanks.

 

[SilentShooter]

Always calculate the load off of 12v, not 14.4

Second you never want to max out the fuse. I try not to go over 80% load.
Lastly I never put an HID on a meter to know if it has a higher initial load during striking or not.

 

[Taxman]

Even at 12V, the 15A switch circuit should sufficient. Do you think the 30A (Aux 1 or 2) is sufficient? Or should I split them? 2 lights per 30A switch? That just seems like overkill for 2 HID lights.

 

[Deleted member 12951]

Use a 20amp relay then you can put it even on Aux #4 if you wanted

 

[Taxman]

I didn't put any relays since I was using the upfitters. I cut up the wiring harnesses and ran straight to upfitters. I'm looking for the path of least resistance at this point. Changing the wiring behind the glove box from Aux 3 to Aux 1 is the easiest at this point, I'm just not sure if it is sufficient.

Putting in a relay is just too much work right now. As is separating and wiring to two Aux switches. I'll do it only if I determine I have no other choice.

 

[Deleted member 12951]

Gauge of wire on Aux 3 and Aux 1 is different. I wouldn't switch them around. I was running a blackhawk 30" LED on Aux 4 for quite a while, with a 40amp relay.

 

[farman]

i don't know much about electrical. But don't hids draw alot more on start up, then go back down.

 

[Taxman]

I'm going to split the lights into pairs and separately connect each pair to Aux 1 and 2. It's a pain in the ass to re-do the wiring, but at least I'm sure it'll be correct and won't have excess relays and wiring in the engine bay.

I'll report how it works and post pictures.

Thanks.

 

[SilentShooter]

Why split if you are going to put them on the large amp circuit.

 

[JayneCobb]

HID lighs have a larger current draw when switched on and will settle out after a second or two. The steady current you have now would be 11.66 amps. You are spiking above 15a when turning them on.

I'd say get a 30 pack, a fifth HID, some good tunes and spend a day rewiring all five lights to aux one or two.