Wiring in Relays

[Mariner]

So I'm tapping into the passenger side fuse box (specifically to the rear heated seat fuse) to power my front and rear light cubes. I have two 20 watt white cubes and two 12 watt amber cubes in the front, and two 20 watt cubes in the back. I'm wiring these to my Crown Offroad dual switch.

My question is, I'd like to use relays so I'm not overburdening my rear heated seat circuit if I have all 6 lights on, so how exactly would I wire in my relays, assuming I want one relay for each front and rear lights?

Any simple explanation or schematic would be helpful, as relays have always been a foggy concept for me to grasp. Thank you!

 

[Dane]

I'll try a simple explanation. A typical relay like you'll probably use has four posts. One post allows you to wire power straight off of your battery, so think of that as power in (this is your large power draw). There's also a power out (to your lights), a ground, and what I like to call switching current (in your case the power from your seat going through your switch). When you apply power to the switching current it closes the circuit from the In (battery) to the Out (your lights) and voila! You have light. The switching current is VERY low draw, so pretty safe to tap from wherever. The full light power is coming from your battery/charging system.

There is a technical way to say all of that and I hate it cause it's super confusing to a non-electrician!

Make sense?

Here's a good basic drawing, try not to over-think it and disregard the middle post for your purposes.
30 is your power in, 85 is ground, 86 is switching current, and 87 is power out.


So, ground 85 somewhere convenient, run 30 to your battery, run 87 to your lights, and hook 86 to your switch you referenced.

Sure hope I got that right. I always play with a 12v wire and a multi-meter every time to make sure I'm sane

 

[Mariner]

@Dane that's perfect, thank you! Mainly I was concerned with overburdening my fuse tap, so with the relay I can bypass all of that safely.

Haha funny thing is I'm a marine engineer so I have a steady grasp of electrical components, but relays have always eluded me for whatever reason.

 

[Dane]

@Dane that's perfect, thank you! Mainly I was concerned with overburdening my fuse tap, so with the relay I can bypass all of that safely.

Haha funny thing is I'm a marine engineer so I have a steady grasp of electrical components, but relays have always eluded me for whatever reason.

Yeah, I wouldn't run the lights off of your seats! Are your Aux all used already? Those would be my first choice over whatever switch came with the lights.

 

[Mariner]

Yeah, I wouldn't run the lights off of your seats! Are your Aux all used already? Those would be my first choice over whatever switch came with the lights.

Yeah all my aux switches are taken lol. I have a crown offroad dual switch for my cubes, so I've been trying to figure out the safest way to tap into power to power all my cubes. I have inline fuses already, but I want relays as well.

 

[2014RubyRed]

Yeah all my aux switches are taken lol. I have a crown offroad dual switch for my cubes, so I've been trying to figure out the safest way to tap into power to power all my cubes. I have inline fuses already, but I want relays as well.

Mariner - if it was me I would run an Auxiliary power wire into the cab from the battery. That way you have steady power and not worrying about a fuse tap falling out or causing issues within your fuse box. That's just me though, don't take that as the gospel. I just like to know that I'm not gonna goof up something stock......

 

[Mariner]

Mariner - if it was me I would run an Auxiliary power wire into the cab from the battery. That way you have steady power and not worrying about a fuse tap falling out or causing issues within your fuse box. That's just me though, don't take that as the gospel. I just like to know that I'm not gonna goof up something stock......

How would this help me though if I need a switchable power source? You know the crown switches are wired I assume, so combining that with a relay, I need to make sure my lights turn off with the key

 

[Dane]

Mariner - if it was me I would run an Auxiliary power wire into the cab from the battery. That way you have steady power and not worrying about a fuse tap falling out or causing issues within your fuse box. That's just me though, don't take that as the gospel. I just like to know that I'm not gonna goof up something stock......

This IS a good point since you already have to run a wire to the battery anyway.

 

[2014RubyRed]

This IS a good point since you already have to run a wire to the battery anyway.

Dane - I think he is planning on using the fuse tap for the power......

 

[Ironhorse07]

Mariner - if it was me I would run an Auxiliary power wire into the cab from the battery. That way you have steady power and not worrying about a fuse tap falling out or causing issues within your fuse box. That's just me though, don't take that as the gospel. I just like to know that I'm not gonna goof up something stock......

X2 and put a fuse on the auxiliary wire as close to the battery as possible.