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Old 05-13-2011, 10:09 PM   #31
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no worries im new to this too but im stuck at a desk job so ive been googling like crazy.....
this link was helpful Wire Gauge Amps Ratings for 12 volt Automotive Systems as was this thred

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Old 05-15-2011, 04:34 PM   #32
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I dont get it? If relays are needed then I have ordered 3 sets of offroad lights and none of them came with relays?

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Old 05-15-2011, 06:05 PM   #33
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They aren't 100% needed. If you have a switch and power source large enough to carry the load of the lamps.

Where you use a relay is where you don't have a source large enough to carry the amp load safely. For example, if you tap into the headlamp high beams to run your driving lamps also. The stock wiring is adequate to run the factory lamps, but adding another pair may push them past their rating.

So you use the high beam wire to trigger the relay, a minor amp draw. The relay has it's own fused power source capable of handing the load of your new lamps.
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Old 05-15-2011, 10:48 PM   #34
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Yea mine have with inline fuse. So really if the power was too much it would blow the fuse. And I'm not running powerful lights so I'm good
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Old 05-16-2011, 01:33 PM   #35
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Quote:
Originally Posted by bc3_Jeep View Post
First......ANY TIME you add components to a circuit it makes it inherently more complicated. Relays are merely energy control devices that are NEEDED only in the event that your switching device is incapable of handling the energy.
If they're such a complicated device that aren't really needed, why does Jeep use them to control the headlights? Why wouldn't they simplify the vehicle's wiring and save themselves some money on every Jeep and just not use relays? (The answer is because they add a margin of safety, which is why I stand by my suggestion to the OP to go ahead and use one as he is planning to do.)

Jp Magazine recently ran an article showing how to add aftermarket lights to your Jeep. Here are the two main wiring diagrams they posted as well as the comments that accompanied each picture:

Quote:
Originally Posted by Jp Magazine
This is the way most people do it and the way many lighting manufacturers' harnesses arrive. There is nothing wrong with this setup, and if you are using an illuminated switch you will need to put a switched positive to the, er, switch anyway.


Quote:
Originally Posted by Jp Magazine
Here is the correct way to do my favorite light wiring. By switching the ground on the relay, all the positive wires are in the engine compartment for an added safety factor; if your switch goes bad, you can just put the wire to ground to light them back up again.



Personally, I prefer to follow the second method and minimize the 'hot' wires running around in my vehicle's cockpit. YMMV.
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Old 05-16-2011, 03:42 PM   #36
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^^^I have ran a few grounded switches like above. There's drawbacks to both methods, so do what you prefer.

And the manufacturer uses relays for a few reasons, for one, space and size of the switch is crucial. If they rated everything to handle the power, the wiring would increase, making it larger and weigh a lot more. Also, the switches can only be so large in some areas, so they have to keep their size down. While a relay does give it one more thing to go wrong, it's not too likely and it's still a simple circuit. A complicated circuit woud have IC's involved etc.....not a relay. If you've ever had a complete harness out of a vehicle, they easily weight 50lbs. Now up the gauge of wiring on most of the wiring and it would easily double the weight. Not to mention the cost of materials would increase.
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Old 05-16-2011, 03:46 PM   #37
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IMO I would never hook up a set of aux lights without a relay. In 25 years of professional electronics, I have seen way too many burned vehicles because of skimpy decisions.
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Old 05-16-2011, 04:26 PM   #38
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Quote:
Originally Posted by Ibuildembig
IMO I would never hook up a set of aux lights without a relay. In 25 years of professional electronics, I have seen way too many burned vehicles because of skimpy decisions.
So I'm new to this. Is there different relays and I have 3 sets of offroad lights, can I use one relay for 3 sets with 3 different switches?
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Old 05-16-2011, 04:34 PM   #39
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So I'm new to this. Is there different relays and I have 3 sets of offroad lights, can I use one relay for 3 sets with 3 different switches?
No. One relay per set of lamps if you are running 3 switches.

And yes I agree 100%+ with using relays. Sure it's a little more wiring involved but I like the safety part of them.


Sherpa, I LOVE the idea of the grounding switch instead of a hot switch.
Honestly I've never even thought of doing it that way.

I guess the only down side would be if you wanted a lighted switch.

I have enough brain cells left to know if my switch is up the lamps are on, down means they are off.
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Old 05-16-2011, 06:37 PM   #40
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Sherpa, I LOVE the idea of the grounding switch instead of a hot switch.
Honestly I've never even thought of doing it that way.
Yeah, whenever I have that option I will run a ground input through my cockpit switch instead of the voltage input. I've done this with dozens of installs over the years, from auxiliary light sources (as mentioned here) to solenoids for multi-stage boost control on my former turbo minivan, to a manual switch that forces on the electric radiator fan, to custom switches that individually control each taillight on my car, and on and on. It's a very simple and elegant way to go.
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Old 05-16-2011, 06:46 PM   #41
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using method 2 would you not want a lower amperage to operate the relay than running directly from the battery?
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Old 05-16-2011, 07:05 PM   #42
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jebby, I would just go with a pair of fuses, one for the load carrying line, the other for the trigger feed side. Just Y off the line at the relay. Fuse the trigger line at the relay, the main at the battery. Got ya covered both ways then.

Or run two separate fused wires.
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Old 05-16-2011, 10:19 PM   #43
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Sounds like a plan I think i like option # 2 better but i guess ill decide for good once i get into it
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Old 05-17-2011, 11:25 AM   #44
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Quote:
Originally Posted by Shelby427 View Post
Or run two separate fused wires.
This is how I run a setup like this.
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Old 04-15-2014, 02:39 PM   #45
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Does anyone know about adding in to existing systems? I have two KC front mounted lights already on my Jeep (on there when I bought it) which I believe came with a KC wiring harness, but I haven't checked. I'm looking to hinge mount two more KC slimlights i think they are driving series. My question is, would I better off just scrapping the existing wiring harness and rebuilding my own, or tapping in to the current harness? I want them all on the same switch. Also I'd really like to hear about how to tap the holes for the the hinge mount cleanly.
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Old 04-15-2014, 02:55 PM   #46
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Quote:
Originally Posted by YJWarrior View Post
Does anyone know about adding in to existing systems? I have two KC front mounted lights already on my Jeep (on there when I bought it) which I believe came with a KC wiring harness, but I haven't checked. I'm looking to hinge mount two more KC slimlights i think they are driving series. My question is, would I better off just scrapping the existing wiring harness and rebuilding my own, or tapping in to the current harness? I want them all on the same switch. Also I'd really like to hear about how to tap the holes for the the hinge mount cleanly.
Just get a new wiring harness with your new KC lights and wire the relay along with the existing relay so that they are both triggered by the same switch (If you want all 4 to come on at once) Personally I would want to be able to use them independently. The existing wiring harness and fuse is not sufficient to just add two more lights to the same circuit.
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Old 04-15-2014, 04:52 PM   #47
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Originally Posted by Shelby427 View Post
bc,
I apologize if I erred in some way, please let me know so I may learn also.

For the reference material I used not only the info from the offroad site.
Wire Gauge Amps Ratings for 12 volt Automotive Systems

I also checked the service manual for what Jeep themselves use, and confirmed such on our Jeep.

And looked at my KC Daylighter's. They came with 16 gauge wire, and are 130 watt versions.
KC Hilites Daylighter 130 Watts Halogen Long Range Off-Road Lights - KCH630SERIES

Jebby I guess I should apologize to you also for recommending a larger gauge wire then Jeep themselves uses on the 55 watt factory lamps. They use 18 gauge and a 20 amp fuse.

Unless I'm explaining it wrong, the larger wire being able to handle more amps and watts, even though your load is not at that rate, would allow for less voltage drop over a distance due to less resistance.
Jeeps use of 18 gauge wire for the factory fogs is just barely sufficient. Wire size not only has to do with amperage, but especially in dc wiring, has everything to do with length of the run and voltage drop. It's always better to er on the large size in automotive wiring. As far as relays go, I personally like keeping the lighter gauge wire behind the dash, so I generally use them. That's not to say that it's necessary or mandatory. I agree that a heavier duty switch and wiring could be used without issue, but I prefer to keep the higher amperage circuits under the hood and the lower amp circuits in the cab.

I think if you look, you might find that your KC lights came with a pair of 16 gauge wires....mine did.

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