Full 12 volt conversion of M931A2, what would need to be done?

[Strouty]

I recently acquired a nice M931A2, I know the 6CTA 8.3 came in lots of civilian applications so I should be able to get an alternator and starter. I need to run a 12 volt electric brake trailer for the time being and I was not sure if the 24 to 12 volt converters were the way to go. In the near future I am planning on installing an allison MD3060P transmission and it will need 12 volts as well. Is there a reason I should not do this? Will all the gauges and lights need to be changed as well? I was told there is a way to run a 12 volt alternator at the same time as the 24 volt one, this may be another option. My other long term thought is to just run a civilian style cab, like a freightliner FL60. I am sorry if this is blasphemy on SS, but I am not really partial to the military aspects of the cab as I am going to be using it for my work truck. It seemed to be the cheapest all wheel drive starting point for medium duty trucks. What would you guys suggest?

 

[FullSpecial]

Top is 12v, bottom is 24v. Truck runs on 24, toys/trailer connection 12.

 

[Strouty]

More details please. Where did you get the parts? I know some ambulances had 2 alternators. Another thing, do you have another 12 volt battery system as well?

 

[NDT]

12 volt conversions of 24 volt trucks have been popular for vocational use of these trucks forever. Gut out all the 24 volt components including gauges, sending units, CTIS, ABS, lighting, PCB, starter, alt and replace with civilian off the shelf parts. Then put the 24 volt parts in the classifieds here to recoup some money.

 

[FullSpecial]

I got the idea and name here so I'm sure I can post it: http://wolverinetechnologiesllc.com/M925Alternator.html
I started with the 24v, looked at the dual set ups listed for the Deuce, and called them back. Had them sell me a 12v
with a serpentine pulley. Bought a second Alt bracket here, designed a plate mount for two brackets and bought new
longer metric bolts and lock nuts. We could PM the fine details if you wish.

 

[74M35A2]

I have modern lightweight 2014 model gear reduction starters in 12V new ($250), 12v used ($100), and 24V new ($300) available, all tested with warranty if interested.

You may need to increase the wire gauge for the starter since the 12V version will draw twice as much current as the 24V part it is replacing.

Your fuel stop solenoid will need to change to 12V also.

 

[doghead]

I would just add a good 24 to 12 converter.

 

[74M35A2]

What is the continuous and max draw of the trans you intend to use? Suprman recently listed some nice converters in the $250 range, and they seemed like decent quality.

You could always tap 12V off the battery bank, though it is usually a controversial issue. I do it without issue.

 

[Strouty]

I do not know the current draw of the transmission yet, frankly I am not sure how to figure that out. I was looking at another thread and someone had an LMTV and it had a 12 and 24 volt generator all in one. Until I commit to the civilian cab, I will probably go with an additional alternator and set of batteries. I would be afraid the converters might hurt the transmission ECU.

For those that have a converter, how long have you had it? Does it seem to be consistent as far as voltage? I know that for a trailer brake setup, it would need to vary amperage based on how much braking I am doing. Can a converter even handle this?

 

[doghead]

Converters can be cheap(simple) or expensive(complicated).

A good one will do all you need. You need to know what you need though.

 

[Strouty]

Can you guys point me in the right direction for a decent converter? The trailer brakes are going to draw more than the transmission would.

 

[doghead]

Google search, 24dc to 12dc converter. Or, dc to dc converter.

Narrow it down by adding an amp rating(when you know what you need).

http://www.newmarpower.com/Landing/DC_Converters.html

 

[Strouty]

Looking at the alternators that I would normally have, my guess would be that 100 AMP would be more than sufficient. I see they have output voltages of 12 volt and 15 volts, my normal 12 volt alternator would be about 14 volts, should I consider the 15 volt version?

 

[Csm Davis]

Okay I want to put my 2 cents in I would go with the 12v and 24v alternators and you can keep your batteries and just take one 24v pair and make them a 12v pair use the same main ground but on the 12v pair go positive to positive and ground to ground and leave the other pair of batteries hooked up 24v. Also look at moving the 12v taps that are already in the battery box to your 12v side.

 

[Strouty]

That would work. I am going to take a look at my civy 5.9, the replacement alternators seem to fit both motors. Maybe I can make something work from parts I have all ready.

 

[74M35A2]

Can you guys point me in the right direction for a decent converter? The trailer brakes are going to draw more than the transmission would.

Here is an example. Would likely work best if it was connected to its own 12V battery to absorb and handle loads accordingly. I have never used one of these, and don't know a lot about them, but I would further research it if I was you and go from there. It may or may not put out charging voltage (> 12.8VDC), so don't know if it could charge a 12V battery, or just supply 12VDC.

http://www.steelsoldiers.com/showth...100-amp-DC-DC-12-volt-step-down-converter-new