Question AUX switches - single switch wired to 2 relays for 2 circuits

[Broncolli]

Hi All,

I am planning on getting 4 lights for the bull bar on my truck. The lights are sold in pairs and each pair comes with a wiring harness, relay, and its own switch. Since I am getting 2 pairs, I would have 2 switches. I would rather use the AUX switches for this, My understanding is that the harness will get power from the battery, and the switch simply closes the coil in the relay to allow power to go to the lights.
- My question - if I have 2 harnesses, I want both controlled by 1 aux switch. So ideally I would have 2 relays, 2 connections to the battery, and 2 grounds. I would have 2 leads to the aux switch, one from each harness. Is it OK to have 2 harness leads connected to 1 AUX switch (single lead), going to 2 different relays?
(my lights will have 2 leads each, amber and white, and I realize in reality it would be 2 amber leads going to switch 5 and two white leads going to switch 6. I was trying to simplify it in my example) (the six-mode switch in the picture would be replaced with the single mode AUX switch to power only 1 mode - who needs strobe lights anyway?)

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[Sledge]

Yes.

I would take a look at the current draw for your relays, to make sure that when you combine them you don't require more oomph than one of the lower amperage aux switches. But honestly i would be stunned if that turned out to be the case.

 

[Bmadda]

That's exactly how I would do it! Those relay coils don't draw much current at all...which is the point of using a relay...a low current circuit to activate a high current circuit

 

[SCB FabWorx]

I would take a look at the current draw for your relays, to make sure that when you combine them you don't require more oomph than one of the lower amperage aux switches. But honestly i would be stunned if that turned out to be the case.

^^I agree with what Sledge Said!!

 

[Broncolli]

^^I agree with what Sledge Said!!

Thanks - how do I determine the current draw on the relay? Is it the same as saying how many amps you need to activate the coil in the relay, and if my 10 amp AUX switch can supply enough power to trigger 2 relay coils at the same time ??

 

[SCB FabWorx]

Thanks - how do I determine the current draw on the relay? Is it the same as saying how many amps you need to activate the coil in the relay, and if my 10 amp AUX switch can supply enough power to trigger 2 relay coils at the same time ??

Yes, that is correct. I can't imagine a relay needing more than an amp to operate the coil.

 

[Tye]

Yes, I have 6 LP4's with 2 relays and all of them controlled by 1 Aux switch. The wiring harness is dual 10 gauge wires feeding 3 LP4’s each parallel to each other. So I have 2 power wires going to the battery, 2 grounds, and the trigger switch for all the lights going to the 1 Aux switch.

 

[Owl]

To determine the current-draw from the coil you have to know something about the coil itself (or) assume its like any other on the market. Looking on Amazon at one selection they give the coil stats as:

Nominal Coil Voltage: 12 V DC; Coil Power: 1.8 W; Coil Resistance: 80 Ω; Must Operate Voltage: 6~8 V DC; Must Release Voltage: 0.6~3.6 V DC; Maximum Applied Voltage: 15.6 V DC

The formula I = Volts/Resistance gives current (I). In this case you have 12/80 = 0.15 amps. Double that for two (i.e. 0.30 amps).

If your relay doesn't say and you have an ohm meter... hook it to the coil leads and get a reading. The ohm value given won't be exact, but its close enough. It'll probably read something like 30,40,60, or 80 ohms (like my example above).

Formula: Amps = Volts / Resistance. Just look up "Ohms Law" for a complete explanation.

Since I assume an AUX switch can handle at a minimum 5-15 amps... just about any type of relay (other than one with a shorted coil) should work.

 

[dejones64]

I have that setup. Two pairs of Rough Country Osram ditch lights (A-pillar and top of bumper). Each pair having it's own harness with a relay and a fuse, connected to Aux 1 (highest amp rating). Amp draw for the 4 lights is less than the Aux 1 rating.

 

[Gnomad]

I have RC fog lamps set up, 3 relays run 6 lamps, one aux controls the relays. At some point I'm thinking I may split the switches so one aux runs the outside lamps for some extra coernering light power and another aux switch for the rest of them. That's why we have relays.

 

[Strizzo]

Do you know what the draw is on the lights? You might be overthinking things. If you can run all four lights off one 10 or 15A aux switch why not just do that? Much cleaner wiring that way.

 

[SGXIX]

How would you guys connect these to aux switch if only having 1 harness for the front 2 fog lights? The cable that leads to the switch has 3 wires (blue, white, black), however I suppose only one of those should connect to aux switch wire...

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