I have finished what the previous owner started, that being the complete conversion to 12V. The only downside is that the trailer light connector puts out 12v instead of 24v, but hold on to your horses! With a single $100 inverter off of ebay, you can power the mil connector, and be done with it. All mil lighting lines start as 12V lines, which control some relays that then gate 24V out to the plug. So, by lifting the feed source off of 12v and putting it on the output of the ebay inverter, I should get a healthy 20 amps to the lighting connector. Considering that the 12/24v alternator only puts out 15 amps at 24v, this exceeds the standard capacity a bit. Enough so to be able to add a funky mil radio in the cab. I have not actually added the inverter, because I don't plan on hauling a mil trailer. The schematic wiring diagrams support my plan, however.
As for the rest of the conversion, the starter was swapped out for a 12v one, as was the alternator. The 12 and 24v lines were just simply joined together. The fuel solenoid is supposedly 24v, but in my case, someone in the military or the Forest Service (a previous owner) must have changed it to 12v, because that is what I found in there, believe it or not. I changed out the relay by the ether can, but it may also have been a 12v unit, for all I know. I am going to check to see what it's pull-in voltage is. I think that relay runs the Jakes (which work fine, btw).
So there you have it. Pretty simple, and there is none of the hair pulling 12/24 stuff to deal with anymore. I have 3 group 31 truck batteries in parallel, although two will start the truck fine in 50 degree weather. Each battery has 950 CCA available. The last issue is the wire sizes. For a given power, if you halve the voltage as I did, you will need to push twice the current through the wire. Fortunately for us, the military over-does stuff to the point that there is no significant heating of the heavy battery cables that run to the starter or the alternator.
Foot note: The slave port on the side of the battery box now produces 12v, which is dandy for a 12v winch I have for recovery work. I can cable over to the winch with a standard NATO slave cable that I keep on board for jumping 24v vehicles. Now to find a flame suit to incur the wrath of the purists!
Irv
As for the rest of the conversion, the starter was swapped out for a 12v one, as was the alternator. The 12 and 24v lines were just simply joined together. The fuel solenoid is supposedly 24v, but in my case, someone in the military or the Forest Service (a previous owner) must have changed it to 12v, because that is what I found in there, believe it or not. I changed out the relay by the ether can, but it may also have been a 12v unit, for all I know. I am going to check to see what it's pull-in voltage is. I think that relay runs the Jakes (which work fine, btw).
So there you have it. Pretty simple, and there is none of the hair pulling 12/24 stuff to deal with anymore. I have 3 group 31 truck batteries in parallel, although two will start the truck fine in 50 degree weather. Each battery has 950 CCA available. The last issue is the wire sizes. For a given power, if you halve the voltage as I did, you will need to push twice the current through the wire. Fortunately for us, the military over-does stuff to the point that there is no significant heating of the heavy battery cables that run to the starter or the alternator.
Foot note: The slave port on the side of the battery box now produces 12v, which is dandy for a 12v winch I have for recovery work. I can cable over to the winch with a standard NATO slave cable that I keep on board for jumping 24v vehicles. Now to find a flame suit to incur the wrath of the purists!
Irv
