M925 12 volt wiring supply from batteries?

[Alan Hodds]

Hi,
I own a 1987 M925A1 and I would like to know where the single wire from the quad battery pack goes to as the diagram under the seat suggests it is a 12 volt feed. Reason for asking is because I have a couple of 12 volt items I need to feed ie a rear view camera and a EGR sensor unit. Any help would be appreciated.
Thanks,
Alan Hodds (UK)

 

[98G]

It feeds the low speed fan.

You don't want to use that kind of tap for powering your stuff... evil tap. Ruins batteries....

 

[simp5782]

Hi,
I own a 1987 M925A1 and I would like to know where the single wire from the quad battery pack goes to as the diagram under the seat suggests it is a 12 volt feed. Reason for asking is because I have a couple of 12 volt items I need to feed ie a rear view camera and a EGR sensor unit. Any help would be appreciated.
Thanks,
Alan Hodds (UK)

http://www.thosemilitaryguys.com/24-volt-to-12-volt-converter/


You can run small feed items like a phone charger or something with low amps.

Sent from my SM-G935P using Tapatalk

 

[Alan Hodds]

Hi,
Thanks for the feedback on the 12 volt feed on my M925. Question regarding your tweaks to the 855 Cummins in your M923, What sort of power increase have you seen with the #18 button and the dual fuel line mods?
Thanks,
Alan

 

[simp5782]

Hi,
Thanks for the feedback on the 12 volt feed on my M925. Question regarding your tweaks to the 855 Cummins in your M923, What sort of power increase have you seen with the #18 button and the dual fuel line mods?
Thanks,
Alan

with an empty truck and no trailer it is very quick. As far as power increases while towing it is pretty noticeable. My mpg while towing is around 5.3 or so in which most trucks only get 6 when they are empty. You have to give her more air as well. Why I have my intake system. She just needs to breathe. ThoseMilitaryGuys.com makes a cage and filter package that allows more air flow thru the stock filter housing.

 

[74M35A2]

I disagree with above. You can pull 12v from one battery. The mil even does it in the original configuration, and it is convienently switched at the dash switch also.

 

[silverstate55]

I disagree with above. You can pull 12v from one battery. The mil even does it in the original configuration, and it is convienently switched at the dash switch also.

If you are using a battery disconnect switch, make sure that you run the 12V ground through it as well; the factory 12V feed has a separate ground return wire that runs right back to the batteries, you will have to run it through a disconnect switch as well with your 12V accessories. Otherwise, with the 12V tap, it will backfeed into 24V items and cause all kinds of weird electrical issues. Please don't ask me how I know this. I ended up going Simp's route and installed the TMG 24V-12V converter; it works well for low-amp draw add-ons.

 

[simp5782]

You have to run a converter unless it is something low amp. The Military runs a breaker on the 12v side switch for the blower motor located behind the dash.
You can install two resistors inline off the 24volt side of the battery and then add your accessory to a wire BETWEEN the resistors. This does not work with things that change their amperage flow. You would need both resistors to be the same as whatever your powering.