Adding a 12 Volt System to a M35A3

[redneckepj]

Our Fire Dept. receintly acquired a 1993 M35A3 from the DOD for converting into a Brush Truck. We have done a lot of research on running our 12 volt equipment on the 24 volt system (converters, ground isolation, dual charging alternators and adding a seperate alternator for a independent 12 volt system). We have decided that the latter is the most cost productive as well as railure resistive method. Here's my problem: All the information that we have found is for the older multi-fuel engines. Ours is equipt with a 3116 CAT engine and sports a single cerpentine belt as well as minnimum room to mount the second alternator. HELP!

 

[Warthog]

Spend some time at the following website:

www.roscommonequipmentcenter.com

They have spent ALOT of time developing solutions for the Fire Fighting industry.

I don't know if they have done anything for the A3s yet. You may have to be the test subject.



All though there are no pictures, here is how one person did it.

http://www.m35a3.net/forum/index.php?topic=44.0

 

[glcaines]

First of all, welcome to Steel Soldiers. I have an A3 and I simply ran wiring from one battery up into the cab. Very easy and works well. I terminated with a fused cigarette lighter receptacle. I plug CBs, GPS, radios, etc. with no problem. If you are trying to run something that is high amperage, such as a winch or pump, that might be another story.

 

[steelandcanvas]

Do a Google search on DC to DC coverters. This might be the ticket for you with your lack of space and single serpentine belt.

 

[fireline1919]

We appretiate the help!

Redneckepj and I have been banging our heads against the wall over this issue. The scary part is it is the first step of many for this project and the 180 day time limit isn't helping. If anyone stumbles upon any more information that might help with this issue please let us know. I will post updates and pics as we go. Thanks!

 

[Happyland1410]

As someone else mentioned, if you are not running high amperage 12 volt items you can simply tap off of one battery for the 12 volts. Our fire department's old m35a2 ran the radio, lights, and siren this way for many years without problems. I wired our new m35a3 the same way last year. There obviously can be issues with uneven draw from series connected batteries but we have not had any issues with the size loads we have. To be a little better you could tap each battery for 12 volts and divide the loads between them but then you have to deal with separate grounds. When you are on an all volunteer department with very limited funds you try to find the least expensive way to make things work.

 

[fireline1919]

We ended up adding a 12 volt system to the deuce. Custom built an alternator bracket and mounted the 12v alternator beside the 24v one. There is plenty of room under the driver side to mount two batteries, mount fuse blocks and circuit breakers, and run wiring. We had a custom single wire, 200 amp alternator built. The truck is almost finished. Redneckepj or I will post pictures when we are done. Thanks to everyone who provided answers to our questions.

 

[fireline1919]

Pictures of the 12 volt system

Sorry it took so long to post some, but we have been pretty busy. With help of the wiring diagrams found at www.roscommonequipmentcenter.com (Most Helpful!), we wired the system in the single wire method. The wiring diagram for the other method is there as well. The only difference in what they show and what we ended up doing is we added a battery disconnect switch. This is a must if using the single wire method. The alternator bracket is custom made by us. We read a lot of materials that talked about the brackets breaking from the vibrations so we built a beefy one. You can see where we mounted it in the pictures. For the drive pully we mounted a double v pully to the 24 volt cerpentine pully and had a machine shop balance it for us. We are running two belts...just in case for lack of a better reason. If anyone has a question, complaint, or better idea please send me a message! I appretiate everyone's input!

 

[fireline1919]

Well, that didn't work! Let me see if I can get them on here. If you can't see what you want or need to see then send me a message and I'll see if I can get better one's taken.

 

[fireline1919]

More pics...I hope.

 

[Warthog]

A basic primer

http://www.roscommonequipmentcenter.com/news_notes/nn9.pdf

 

[M1031CMT]

Looks good to me. Very simple and straight forward. Usually the simplest solutions are the best ones.

Good looking truck. Though I find it odd why someone painted the spare tire.

 

[fireline1919]

Yeah, we found the white tire to be comical! We told them to just worry about taping off the glass and lenses...they took it to heart. However, I can't complain. The paint was donated by a local body shop's paint supplier and the labor was donated by the body shop itself. It's just going to get scratched off in the brush anyway.

 

[fireline1919]

The primer is a great option. In our project vehicle we opted to use the disconnect switch to keep it as familiar to the other volunteers as we could. All of our other trucks have a disconnect. We have to keep it as routine and compairable as possible. The option was just better suited for us. There are a lot of options available. Just use what is best for your application.

 

[Warthog]

I just scanned the RCE website. What report/project did you use?

Take any pictures/drawing of the alternator bracket?

 

[fireline1919]

We used the "Adding a 12 Volt DC Charging Circuit" report. I contacted the folks at RCE and asked them specifically about adding the system to a M35A3. They have not done so to this style deuce. They couldn't tell me if there was a way, but would let me know if they could find where someone had performed such a task. I am a certified diesel service tech and worked for Caterpillar and John Deere for 7 years before I became a career firefighter. The other gentleman that was working on this project is an excellent mechanic also. We put our heads together and worked it out. I don't have a picture of the bracket at this time, but we have talked about pulling it off and taking some. I will see if I can get that done pretty quick. We also put some thought into the pulley. We were afraid that the AC Delco Auto style alternator that we had built would not turn fast enough to initiate the charging circuit. We installed a smaller pulley (I will get the exact size) to accomidate. All that it needs to initiate a charge is to set your foot on the accelorator pedal.

 

[Warthog]

Thanks for all you effort with this. With your help, someone in the future will have a little easier time.

 

[fireline1919]

If there is anything that we can help someone with we are ready and willing. We thank you and everyone else that has taken an interest in this subject! If anyone has any other ideas that might work better, we are open to anyone's information. If we can keep these trucks running when they are needed most, then we have all done right!

 

[redneckepj]

Some pictures of the bracket
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[fireline1919]

There are a couple of pics that redneckepj had taken. It's not the most beautiful thing by any means, but it will do the job. (It was his idea to paint the thing JD Green)