Please help, HMMWV Trailer light/power conversion

I'm looking for a converter for my HMMWV that I use as a recruiting aid, ideally the converter would run to a mobile rock wall trailer to run the Brake lights and charge the batteries. I've asked all over town and everyone thinks I'm crazy, any ideas?


I apologize if in my haste I neglected to meet all new member requirements

RV 7 way. Lights are easy. Put 24 VDC bulbs in the trailer, no problem. As for charging a set of 12VDC batteries from a 24VDC system, It's not recomended to pull off of just one battery for a high amperage 12VDC output, but truckers used to do it all the time. We use these at work sometimes.
http://www.powerstream.com/dc1-ap-notes.htm

just get a 24v to 12v convertor for charging the batteries, run 24v lights and you'll be all set.

Scout, if you're in the army, you need to go the motor pool and get them to make you an adaptor box/cable for your 12 pin cable to a civilian 7 pin cable. I pull a civilian trailer that I changed the bulbs to 24 volts on and added a second power lead from the truck to supply 12 volts to the battery charger for the breakaway system (probably the battery you're speaking of right?).

I have a box I mounted on the trailer, depending on the setup, you might want a box you put in the bed of the HMMWV, you run a 12 pin cable to the trailer connector on the back, and plug the 7 pin plug into the box.

To get 12 volts out of 24, you'll need a 24-12 volt converter. I'm not aware of a particular NSN for such an animal, but I do know I have one from a British mfgr. There very well could be such a thing for US MVs. That would go into the box and drop a 24 volt (split if off of the tail light feed)
feed to 12 volts which you'd send to the trailer. You would likely have to run with the lights on always to power the battery charger but it would work.

You could get a 7 pin receptical added to the back of your HMMWV instead of a box. But the box would be portable and it could be moved from HMMWV to HMMWV (or even behind a FMTV or Deuce). Put some magnets on it for "anchoring".

For the lighting, either swap 12 volt to 24 volt bulbs OR get some dual voltage LEDs.

Hmm, I just thought of something, does your rock wall trailer have electric brakes? If so that presents an additioanl issue. You need to provide 12 volts on a resisted (basedon braking force) design for the brakes. That needs an elecronic brake controller.

24-12 volt converters etc

I have a 24 volt unimog and been having same trouble, Found www.redarc.com down in Australia. They have trailer light converters and a adpater to run 12 volt trailer brakes from a 24 volt vehicle and using a reg 12 volt controller. They also have battery chargers that run from 24volt to charge12 volt battey in a trailer etc. For $200-300 I think I will have things solved. http://www.redarc.com.au/tb.htm for trailer brakes EB24A alows to run 12 volt trailer brakes There is a US made trailer converter but it is like $800 and does not provide any way to use electric brakes.

I thought HMMWV's had dual-volt alternators anyways? Something about 12 volts for the transmission controller? There should be a way to tap off of that system.