12 volt relays

[Flea]

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?

 

[mangus580]

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.

 

[Flea]

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

 

[cranetruck]

Relays are good.

 

[comdiver]

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.

 

[kc8sfq]

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.

 

[cranetruck]

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....

 

[Flea]

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?

 

[gimpyrobb]

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

 

[comdiver]

Cranetruck, Can you tell what you used and how?

 

[cranetruck]

Re: RE: 12 volt relays

Cranetruck, Can you tell what you used and how?

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.