12 volt relays

I'm wanting to start on the 12 volt system soon, and I'm thinking of how I want to rig up trailer lights in 12v for civvy trailers.

I was thinking of splicing into the respective electrical circuits and just running a bank of relays to switch 12V power to the appropriate wires. Also will need to run dedicated 12V ground, but that's no problem.

So my question is, will a 12V relay operate with 24 volts? That is, I want to use the 24 volts from turn signals, brake lights, running lights, etc. to switch the relay, but run 12 volts through the unit. Will this work?

As long as you have a 24v controlled relay, yes.

Also.... why do you need a seperate ground? Should be no need, if you ground both systems to the frame.

Duh... dunno why I didn't think of that... Perhaps the new baby and 4 hours sleep...

Relays are good.

I have briefly thought about trailers and 12v hookups also. As many have suggested, if you always tow with the 24v truck just change the bulbs. That being said, I have seen some post by some of you radio and electronic brains out there, could one of you design a converter we could build and use? I was thinking about using a solid state voltage converter for each function; left, right, stop, run, etc. This could be either plugged in and used or wired in with a separate plug. Please.

You could use a solid state 24/12 convertor to provide the 12V, I picked one up for $15 at a ham fest. Then switch it with relays with 24V coils. You'll need 3. one each for left and right turn and one for running lights. It'd be a simple matter to make up a box that takes 24V from the running light wire (and ground) to power the unit and mount the whole thing in an ammo can or other suitable container with a Milspec trailer pigtail on one end and a civie trailer pigtail on the other.

I built a square wave "chopper" for each line a couple of years ago. The 12 volt bulbs run fine on a 50% duty cycle 24volt square wave....

Well, the thing is, the truck is going to see way more use with Civvy trailers than with Military trailers. I want something more permanent than something plug-in. Not to mention, the truck is getting 12V system separate for 12V cab functions, plus auxiliary lighting, and a brake control for electric brakes. The truck will pull a horse trailer, enclosed cargo trailer, 21' Flatbed with a tractor, and eventually a travel trailer. All of which are otherwise pulled with either my Jeep or a F-250, so changing bulbs each time (not to mention buying and storing them) is not a very viable option.

On a side note, does anyone know if MUTT wheels will fit a standard 5-lug trailer axle?

Some are 5 on 5 inch spacing bolt patterns and some are 5 on 5.5.

Cranetruck, Can you tell what you used and how?

Re: RE: 12 volt relays

comdiver said:

Cranetruck, Can you tell what you used and how?

Click to expand...

Generally speaking, I used a linear voltage regulator for each circuit (stop/turn/tail) and let a 60 Hz ocillator enable it when needed. It was pretty compact with 3 input leads and 3 output leads plus a ground. It was only suitable for incandescent light bulb loads.
Unfortunately as with so many things in this hobby, just building a few units makes it very costly.