24volt to 12volt

[fox hole freeman]

Sounds like you know your stuff. I've never been good with electrical. Would just like to be able to hook up to a 12 v trailer or a 24volt M105a2

 

[metalworker393]

Hello all SS members,I have an M35a2c that I am looking to convert to 12 volts from 24 volts.Anyone out there able to post a schematic on how to do this?Electricity is not my strong point,and I intend on adding some 12 volt accessories to my truck.
Of the things I want to do,add a hydraulic hoist for the bed(great for unloading dirt and mulch)a liftgate(ever try picking up fresh cut oak for firewood)and a snow plow(Have a 9' Meyer plow and an E60 pump)
Another thing that has always botherd me is not being able to see the gauges at night.I kinda figure if i have the vehicle converted to 12 volts I can also change some of the gauges so I can see them at night
I read a post from a fella that goes by pjpiche1 converted his deuce fairly cheap.If you read this can you send me a schematic and a parts list?I have also read that a company called Wolverine technologies has a new alternator in either 12 or 24 volts ,and a 12 volt starter.Any help with this would be greatly appreciated,Metalworker393

 

[Stan Leschert]

As has already been stated, the 24V system is a far superior system. I would keep it. As for running a 12V tap off of one battery, I would highly NOT reccommend it. It places an uneven load on an already old and tired system. The weakest part will fail quickly, usually taking out several other key components. The 24>12V invertor is the only way to go. ROBR can tell you where to get them from.

If you require more than 30 Amps, the smart thing to do would be mounting an auxilliary 12V alternator meant for an RV and seperate storage battery. Most alternators now days have a 1 wire connection, and are easy to plumb in. The big pain will be fabbing the mounts. New belts will be required, but just take one of your spares (which you should carry with you) and cut it. Wrap it around your new pulleys, and measure the distance that you are short. Any auto parts store will be able to help you out. When you find the correct size, buy a spare. Make sure to save the packaging so you know which one to buy next time.

 

[m376x6]

The only problem with converting a 24 volt system to 12 volt is the gage of the wiring. Normally the wiring in our trucks is 14 awg. The work a device performs is measured in watts. 24 volts uses half the current that 12 volts uses. For instance, headlights, a headlamp is generally rated at 50 watts. To get 50 watts from a 24 volt system requires a hair over 2 amps, for 12 volts, it requires just over 4 amps. A single device drawing 4 amps on a 14 awg wire is fine, but add the second headlight, the marker lights which now have double the current and all the other devices that require double the current to run at 12 volts and you can quickly overload a 14 awg wire. You can reliably run a 14 awg wire at 15 amps. A single marker light being supplied with a 14 awg wire is overkill, no problems what so ever. But add up all the lights in your instrument panel, your marker lights, your headlights, possibly a spotlight, and all of them being controlled by single 14 awg wire supplying a light switch and the single wire can be overloaded. Also, the internal switch contacts were designed around 24 volts and can burn up themselves. How many folks have replaced a smoked light switch. Even the new pushbutton boxes are subject to failure. Whether you're applying 12 or 24 volts to a 14 awg wire is of no importance, these voltages are too similar and too low a voltage to have any impact on the wire, it's the current or amperage that heats and burns a wire up. There are relaible converters to drop a voltage down to 12 volts. Remember, 12 and 24 really aren't 12 and 24. A typical 12 volt system runs at 13.8 volts and a 24 runs at 28 volts. With upper voltages as high as 15 and 29 resopectively. A simple conerter can be as easy as a resistor, these are okay as long as the load doesn't vary. You'll need to know the current used by the device and this will determine the resistance and wattage rating of the resisitor. Some converters are regulated and will cover a wide range of current loads up to their maximum amperage rating. If I can help you out in any way please fell free to to PM and I'll try to get you some answers.

 

[Flyingvan911]

If it ain't broke, don't fix it. For trailers, try relays in the 24v trailer wires. Then you have a 24volt socket and a 12 volt socket. You can pull both.

 

[tx399999]

If you need 12v the best thing to do is install a battery equalizer. I picked up a 40A model on ebay for a good price. It equalizes the batteries so you you can pull 12v off without draining one battery.

 

[m376x6]

tx399999, I see how the "equalizer" is wired in. Where do you tap the 12 volts from? The red wire goes through a silver device and is tied to the 24 volts out, the terminal closest is tied to the ground or negative in, and the center termial is tied to the postive side of the bottom battery. Is there another terminal on the equalizer that isn't seen? The tapping of the center between two batteries doesn't drain one battery, but causes the upper battery to be overcharged and eventually burn. What is the silver device in the middle, do you know? Thanks

On my M101 I carry both 24 and 12 volt bulbs and a modified connector to conect the standard military trailer harness to the 7 wire blade connector on my civilian truck. The sockets are the standard ba15s if Irecall the number correctly, or the base used by an 1156.

 

[tx399999]

On the equalizer the top terminal is the 24v in, the center is 12v out and the bottom is ground. That's all there is to the installation. The silver thing is a fuse holder, I need to pick one up for the 12v leg too. The equalizer actually splits the input voltage to perfectly balance the batteries. One of these days I'll put together a separate relayed fuse panel for both the 12v and 24v terminals off of it.

 

[saddamsnightmare]

March 27th, 2010.

While it is only a personal opinion (mine), I kinda look at it that the electrical system parts are universal on the M35A2 series when they are twenty four volt DC (24VDC). Sure, the equipment was built by the low bidder (DUH), but then these vehicles have proven their durability in both climate and chronological terms, very FEW modern civillian vehicles will be running 40 to 60 years after they were built, and the parts are there if you need them. New starters in 24VDC aren't all that exorbitant, and a 24 VDC vehicle can start a 24VDC vehicle and most large trucks are 24VDC (or were).
The cold weather starting issues on these trucks often comes down to nothing more then a replaceable, stock, military solenoid for the particular brand and model starter motor. The Intake heaters will kick these beasts over (IF the heater is working properly) much quicker then a civillian diesel will do under similar starting conditions, so why bother reinventing a wheel that rolls??
I have had more problem with 12VDC systems failing then the 24's, and it is because the current draw is halved through the starting system and strains the components much, much less.
Just my .02 worth,

Have fun with your wizardry,

Cheers,

Kyle F. McGrogan