deuce 12v conversion

[Warthog]

Since you are keeping the 12v conversion, you must replace ALL 24v items with 12v versions.

All the bulbs - dash, tail and headlights
All the gauges - oil, voltage, fuel, temp, etc
All the senders - oil, temp, etc

Did you replace the in-tank fuel pump? That is 24v also

 

[doghead]

You may need to rewire some things with the correct gauge wiring, to accommodate the new loads with 12 volts.

Basically, you should re-engineer the whole wiring harness.

 

[JasonS]

My gasser harness uses 14 gauge wire which should be fine for most any normal 12V loads. I'd be more concerned with the light switch but that could also be replaced with a 12V equivalent IF it fails.

 

[steelandcanvas]

Adding a 12 VDC Charging Circuit

Since you are keeping the 12v conversion, you must replace ALL 24v items with 12v versions.

All the bulbs - dash, tail and headlights
All the gauges - oil, voltage, fuel, temp, etc
All the senders - oil, temp, etc

Did you replace the in-tank fuel pump? That is 24v also

Turn signal flasher, starter motor solenoid, air horn solenoid, coil for flame heater, and heater fan motor also. Not a well thought out plan. Here is what Rosscommon has to say:

 

[JasonS]

Nice table of ampacity: American Wire Gauge table and AWG Electrical Current Load Limits with skin depth frequencies and wire strength

 

[Woodsplinter]

Hey guys, Jason has made the conversion, he stated his reasons and he needs help.
Why can't you just help the man out? Consider it a challenge to make it happen.
You guys have forgotten more about deuces than I will ever know- I can't be much help to Jason on this- but you guys can!

Thanks

 

[steelandcanvas]

Hey guys, Jason has made the conversion, he stated his reasons and he needs help.
Why can't you just help the man out? Consider it a challenge to make it happen.
You guys have forgotten more about deuces than I will ever know- I can't be much help to Jason on this- but you guys can!

Thanks

First of all, he is very unclear on what doesn't work, power when the switch is off, no power when the switch is on, his description makes no sense. Photos would probably help the diagnoses. Secondly, he is going to spend alot more money to change everything out that is needed for his conversion. It's not that I don't want to help him, I am, but I/we certainly have our ways on how to do something right. I would rather see him do it correctly and not cobble the truck up and make it more difficult to work on.

 

[Warthog]

Hey guys, Jason has made the conversion, he stated his reasons and he needs help.
Why can't you just help the man out? Consider it a challenge to make it happen.
You guys have forgotten more about deuces than I will ever know- I can't be much help to Jason on this- but you guys can!

Thanks

After his second post, we have been giving him solutions to his problem.

There are ALOT of things that need to be changed to make it happen.

 

[ODdave]

Hey guys, Jason has made the conversion, he stated his reasons and he needs help.
Why can't you just help the man out? Consider it a challenge to make it happen.
You guys have forgotten more about deuces than I will ever know- I can't be much help to Jason on this- but you guys can!

Thanks

I apologize for my WV comment, We ( I ) see alot of stupid things come across on here and well, im just not nice. Some times I speak when I shouldnt.

 

[JasonS]

Hey guys, Jason has made the conversion, he stated his reasons and he needs help.
Why can't you just help the man out? Consider it a challenge to make it happen.
You guys have forgotten more about deuces than I will ever know- I can't be much help to Jason on this- but you guys can!

Thanks

I thought his name was Rob?

 

[saddamsnightmare]

November 2nd, 2012.

In any case, he has attempted to recreate the wheel without any good reason for doing so. Adding a 12 V Alternator and a separate 12 V electrical system would have made a lot of sense. However, as noted above, we have given him a great deal of information, and he has given us no photographs as visual aids, so you may say it is the blind leading the blind.

One last thing, please remember when it is -30F below and you need to fire and crank this beast, you won't have the ampacity in 12V that you had in 24 V, and you will find no manifold heater and a very cold Multifuel engine can be a horrible nasty beast to try to start ( and the CID is almost as great as a Cadillac 501 V-8, which was a horrible beast to start as a gas engine in very cold weather). You might do better to convert back and superimpose a 12 V system for your more modern loads....

 

[AN/ARC186]

I'll make it easy,

Rob, send the truck to me and I'll convert it for you.
I'll get things back to 24V and add a 200A 12V alternator and battery as well as a 12V fuse block.

You are really going the hard way on the conversion you are doing.

 

[scottgs]

I'm no M35 expert, but have been fooling with trucks, radios and emergency vehicles for more than 30 years. In my opinion, converting this truck to 12V is not a wise move, especially if it's an emergency vehicle. I want to help. But I want to help by encouraging the right thing, especially if this is not just someone's hobby or toy, but a vehicle to be counted on and trusted.

The M35 with it's mutlifuel engine was designed with a 24V system. Converted to 12V, it will be a bastard truck that will never perform as well as it originally did. Every electrical part that is changed will now be non-standard for the truck, harder to find or be custom made, probably more expensive and may be poorer performing than the original. Over time the 12V conversion could stress the batteries and electrical system more, and maybe the engine too, since it will probably start harder and slower.

Many emergency vehicles have two alternators installed from the factory. Sometimes with two sets of batteries and two seperate electrical systems. This provides cleaner, more stable and quieter power to the radio equipment and emergency lights. This seems to work out better, even when both systems are 12V. Also, with a seperate electrical system for radio and emergency lights, you will not have to worry about the starting batteries being drained if the radios and lighting are unintentionally left on with the motor off.

I would stop and think it over before going any further. Even if I had to eat crow today, I'd sure rather be known for having done it right in the end.

 

[Rambling Wreck]

OP/Rob, it is hard to help you when you don't respond to questions, or really at all for that matter. I think you have responded only once to this thread (your thread) and it was more defensive than anything else so we weren't able to glean much information from that post. I'll ask you again, what is your total connected load? Additionally, which accessory has the highest draw and what is that load?

The reason people are having a hard time giving you a simple answer is that no one (who has seen this thread at least) has tried such a complicated solution to such a simple problem. We are trying to help you but you aren't making it easy.

If all you have to power is a few flashing lights and a radio, just install a 24 to 12 volt converter after you switch the system back to 24 volt. You could have done this in the first place and it would have only taken you a few minutes and less than $50 for the converter and 10 gauge wire combined. I have a 2,000 watt amp, CB, Stereo, 2 ACC outlets, cab light, and a fan run off of 2 720 watt converters. Some people have suggested that you install a separate 12 volt alternator but I disagree. For the load you have it probably isn't worth the money or effort. That is, unless you want to run a 12 volt winch or a bunch of 12 volt off road lights. In that case the 12 volt off road lights could cheaply be converted to 24 volt so no need for a 12 volt alternator there. That basically means that the only feasible reason to install a 12 volt alternator is if you need to power something with a lot of draw, like a 12 volt winch. It is just so much cheaper and easier to install a voltage converter. The pics below are of my system that is powered by my two 720 watt 12 to 24 volt converters. See my build thread (link in signature) for more details.

This post is not a criticism by any means. Myself and the other posters are only trying to help you. So please help us to help you by responding with more information.

 

[Cleveland Iron]

Learning

Please listen to these people. They are really just trying to help. If I didn't stop a project when I realized I'd screwed up at the beginning, and just decided to bull through... Well, let's just say there are a few projects I started on that I simply discarded and labled as a learning experiance. Some cost more than others but real education isn't always cheap.

 

[RobDuece]

I have converted the whole truck now. I got all the guages working now. The truck is a full 12v truck. I am now down to paint and lettering and installing a consol for radios and stuff. I am hooking up all the stuff to a 220amp alternater.

 

[Rambling Wreck]

Glad it worked out for you.

 

[rmgill]

How did you work out the fuel pump?

FYI, I worked out a 12 volt system myself on my truck with a 24 volt to 12 volt converter to provide power for a 12 volt braking system. This worked under load.

 

[RobDuece]

The fuel pump is working just fine. I have been talking to a local truck refub center on dueces,5 tons,humvees,and all other military stuff. They told me about most of the stuff that i have done. Just ready to get this truck painted and finshed. I want to have it for our fire department so we can use it.

 

[6x6TRex]

The fuel pump is working just fine.

Working fine as in you replaced it with a 12V pump? Or working fine as in you just hooked the stock in tank pump up to 12V and its barely pumping fuel if any?

I converted the truck to 12v to allow me to run emergency lights that do not cost an arm and a leg. I would have added a 12v system but the draw would have been to much. That's why i put a 220 amp 12v alternator on not a 189 amp 12 v

I don't mean to be rude but you do know you now have way under 220A for your lights and siren now that the ENTIRE truck is 12V now right? Instead of adding a 2nd 200A alternator and a 3rd battery to run just the lights and leaving the truck 24V, ALL of your load is now drawing from the 12V alternator; starter, headlights/taillights, turn signals, heater, gauges, it all adds up!

The reason I'm saying that is I'm going to become a volunteer firefighter next year and am going to do the same thing to my deuce when I get one. Without having to convert the truck to 12V!

Tm-america makes a really nice 2nd alternator bracket for the multifuel. A 200A delco 10si alternator plus a 1000 CCA group 31 battery will be more than enough capacity for lights and a siren. Plus everything else on the truck is stock for ease of parts availability, who's going to have a 12V multifuel starter on the shelf?