24volt to 12volt

[fox hole freeman]

Has anyone for any good reason converted their 24volt system to 12?

 

[M543A2]

I have not done it with any of our trucks because we find the 24 volt systems to be very reliable. With 24 volts, it takes less amperage to do the same work, so less strain on everything. All parts are available, so no problem there. It is my thought that most conversions are done because someone is uncomfortable with the 24 volt system, mainly because they think there is some kind of mystery about it. They do not want to risk having problems they think they cannot fix with the knowledge they have from working in 12 volt systems. The work and expense of it is just not worth it to us.
Regards Marti

 

[LanceRobson]

The amount of work involved and the pros and cons change depending on which specific model or vehicle family you are asking about. CUCVs are the trucks most likely to be converted to 12V. Which model are you asking about?

Perhaps a thread title change stating the model will get you better responses. Also, there's a lot of info available through the "SEARCH" feature.

Lance

 

[fox hole freeman]

M35a2

It is a comfort level. Also a desire to use 12volt equipment with it. How can I jump start the system with a 12 volt vehicle?????

 

[army98]

connect to each batt individualy takes 2 power sorces though .

 

[fox hole freeman]

How reliable are they starting in the winter months in cold weather. Mine does have a manifold heater

 

[Carl_in_NH]

If you're worried about winter starting, going from a 24V to a 12V system is flat out the wrong thing to do. You'll need a much bigger 12V battery, and more copper in the wires between battery and starter to crank over the engine when it's cold. Not to mention finding what would be an odd-ball starter wound for 12V operation for this engine. Stick with 24V systems; keep your system charged when not using the truck (two 12V chargers, a 24V charger, or better still run the truck once every couple weeks and keep the system charged). Use a 24-to-12V power converter to run accessories that you want.

 

[nk14zp]

 

[sangamon]

Both my Unimogs and my M656 are 24 volts. I use a little 24V/12V converter for things like my laptop computer, GPS, and stereo.

I needed a jump start once on one of my Unimogs. We just put the 12V jump to one battery for a few minutes, then to the other battery. We removed the cables when starting. We were very careful about grounds and connections, and it worked fine.

As far as cold starting, it doesn't get into single digits very often here in Seattle or Blaine. The coldest I've started is about eight degrees. Instead of starting in one second, the engines took about three seconds. The 24v starter really spins the engine.

 

[pjpiche1]

I converted my deuce to 12 volt. I converted it because everything that I use the truck for needs 12 volt power. I have several civi trailers and an RV/toyhauler that I pull with my truck. Not to mention all of my creature features that I have installed. It only cost me 350.00 to do the complete conversion which is super easy to do. 12 volt starters for these trucks are easy to find. It is a very common heavy equipment starter. It is not an "odd ball ". Fact: the stock 24 volt starters that are in the trucks are actually inferior starters. No matter where I am at now, I can repair my electrical system locally. I live in Ga. But, from time to time it does get below zero here in the winter. The truck starts with no problem. I have never even used the starting aids. The only reason that the military uses 24 volts is for uniformity. They can jump anything from anything.

 

[gimpyrobb]

As stated, the 24v system works just fine. You can get 24v-12v converters like the one Headwizard here on the site sells. You can get a dual voltage alt like in some of the newer trucks. Or there is always the 12v swap. The option that suits youbest, is the best option for you. It costs nothing to keep the 24v system and see how it fits your needs.

.02

 

[1956_4x4]

I converted my M1031 to a 12 volt system years ago. I had no real desire to make the conversion, but the starter burnt up on me and a 12 volt gear reduction starter was cheaper/available. Rewiring the batteries to 12 volt doubled the available amperage and helps out since the fire trucks I might jumpstart are always 12 volt.

I would guess that a "fear of the 24 volt system" would not really be an issue, since a person that makes this type conversion should have a basic knowledge of electronics.

I wouldn't convert a system just for the joy of the conversion. If there is a reason to justify the expense/labor fine, but the manufacturers usually put a lot of time/money into the R&D for their vehicles. Sometimes the design might be to ensure compatibility with other vehicles in the fleet (I believe this is the case with the CUCV vehicles...) or it might be for specific product reliability.

I have been happy with my conversion, since it meets my specific needs. It has not given me one problem and keeps running like the proverbial Timex.

Smitty

 

[Snarky]

Theoretically you could use a 12 to 24v converter and charge the 24v batteries using a 12v vehicle, to get enough power to start. Or you could charge each battery individually. Although, that wont help you if you battery goes bad and you just need to fire it up enough to get the engine going and alternators to power the electronic equipment. It's kind of a non-issue on a deuce though, you don't need a jump, you just need a good hill or a push, **** I bet you could get it going to with the correct application of a breaker bar.

 

[glenn]

Both my Unimogs and my M656 are 24 volts. I use a little 24V/12V converter for things like my laptop computer, GPS, and stereo.

I needed a jump start once on one of my Unimogs. We just put the 12V jump to one battery for a few minutes, then to the other battery. We removed the cables when starting. We were very careful about grounds and connections, and it worked fine.

As far as cold starting, it doesn't get into single digits very often here in Seattle or Blaine. The coldest I've started is about eight degrees. Instead of starting in one second, the engines took about three seconds. The 24v starter really spins the engine.

Hi Sangamon - Where did you find a 24v to 12v converter and how is it hooked in? I just bought a 5 ton and need to do the same.

Thanks,
Glenn

 

[sangamon]

glenn,

I wire the 24V input to a switched circuit, with a fuse. The 12V output just goes to the stereo and a couple of cigarette lighter sockets.

I got my converters from my Mog guy and a stereo shop. However, they're available all over the internet for $20-$200. Mine are at the lower end because I only run a laptop, GPS, and stereo (which I don't turn up so loud that it uses mass quantities of power).

It's certainly possible to make it more complicated, but that was all I needed.

 

[rmgill]

Glenn, I added a 24-12 volt converter myself in order to power a 12 Volt Brake Controller.

 

[mckeeranger]

If you are looking for 12v power in a 24v system, and you have 2-12v batteries in series, why do you need a power converter?

If you pull power from one battery, that's 12v. If you use the battery that has its - terminal grounded to the chassis/body, you can use the chassis/body for your ground, just like a 12v system.

Even on the 5-ton with 4 batteries. You have 2 batteries parallel in series with 2 batteries in parallel, so that's still 24v or 12v for each of the parallel sets. You can still pull 12v from one battery. (Or in this case 2 in parallel)

Sure, the alternator/generator is 24v, but it's dropping that voltage across 2-12v elements (the batteries), so its power is being cut in half by each.

 

[pjpiche1]

You can do that. Only if the source that needs power is very low amperage. If you try to pull a large amperage from one battery, you create is a mis match in the amperage between the two batteries in the series. The mis match in the amperage between the two batteries dramatically shortens their life. If you don't mind having battery problems, It is an option.

 

[Jones]

The baby HEMTT is 12 vdc. With the 5.9 Cummins fuel cut-off solenoid, charging and starting systems already 12 vdc it was an easy choice to go to more readily available (and cheaper) bulbs and LEDs.
DATCON gauges match the original HEMTT instrument panel perfectly.
12 vdc for the radio and heater/AC and that's pretty much all I need.
The only 24 vdc system that couldn't be changed over is the one to run the crane, and that's supplied by a "Power Supply, EMCU 116"; 12 vdc in, 24 vdc out.

 

[mudguppy]

that's interesting, Jones, that you went to 12V. since i am planning to do a 5.9 cummins swap, i was on the same fence. but i actually just picked up my spare starter yesterday: i took it to my local starter shop and they rebuilt the cummins starter to 24V. i thought about the fuel shut off solenoid, but those are readily available in 24V also. but my primary plan is to just use a cable like the deuce is set up to avoid solenoid issues and simplify my starting circuit. charging system is the same: 24V alternators readily available to bolt on. i plan to run a converter for 3 guages that still require 12V (tach, EGT, boost).

i just figured, in my plan, it would be easier to change 2 things to 24V rather than 50 things to 12V.

very cool.