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12 volt question...

sgtmike3

Member
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8
Location
Ohio
My department has a 1998 M998 that we have been working on and using. I have been working on the equipment side, finding 24v accessories, but still have several things that are 12 volt. I know that using one battery to supply 12 volts can cause balance issues with the batteries and shouldn't be done. Could I create a separate 12 volt circuit using BOTH batteries in parallel to balance the load? Or would we be better off getting a DC to DC converter?

Thanks,

Mike
 

steelandcanvas

Well-known member
6,187
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Southwestern Idaho
Doing a search for 12 volt accessories brings up a ton of threads to read through. This subject is brought up quite often, therefore a lot of ideas have been disussed.
 

187

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Location
Youngstown, OH
We used the converters on all three of ours. Our mechanics decided that was the best way. I think they bought them from Eric's Military Surplus:

www.eriksmilitarysurplus.com

We had lots of spare 12V lights, radios, etc so the cost of the converter was minimal.

One was set up with a lot of gadgets so the larger, heavy duty model was used, but the others only needed a few 12V sockets for GPS and cell phone charging, so a "cheaper" one was used on those.
 

Stalwart

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Location
Redmond, WA
Could I create a separate 12 volt circuit using BOTH batteries in parallel to balance the load? Or would we be better off getting a DC to DC converter?
No you can't do that. You have several easy choices by price:

1. 24-12V converter

2. Battery equalizer, it ALLOWS you to tap the battery closest to ground. It balances the load.

3. Dual output voltage alternator, HMMWV's often had these.

Since there isn't a ton of room left under the HMMWV's hood, a second alternator probably isn't as easy as it is in a Deuce.
 

Army Kid

Banned
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0
0
Location
SW
My department has a 1998 M998 that we have been working on and using. I have been working on the equipment side, finding 24v accessories, but still have several things that are 12 volt. I know that using one battery to supply 12 volts can cause balance issues with the batteries and shouldn't be done. Could I create a separate 12 volt circuit using BOTH batteries in parallel to balance the load? Or would we be better off getting a DC to DC converter?

Thanks,

Mike
I use a 40amp 24VDC to 12VDC converter from Sure Power. Powers my dual-electric cooling fans (20a peak load). Fits right into the battery compartment on the HMMWV. Sealed unit & Works great.
 

sgtmike3

Member
38
1
8
Location
Ohio
Thanks for all the help, electricity isn't exactly my greatest area of expertise and I knew I'd find the answer here.

Mike
 

sgtmike3

Member
38
1
8
Location
Ohio
Bumping this old thread to ask a question. We have managed to get a pair of 200A alternators for the HMMWV. These are the dual voltage models. What modifications are needed to go from the stock 60A to a 200A dual voltage? I know the pulley is different, can I just swap it?

Thanks,

Sarge
 

Army Kid

Banned
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0
Location
SW
Bumping this old thread to ask a question. We have managed to get a pair of 200A alternators for the HMMWV. These are the dual voltage models. What modifications are needed to go from the stock 60A to a 200A dual voltage? I know the pulley is different, can I just swap it?

Thanks,

Sarge
I upgraded from my cooked 60A to a dual volt also...
Need to upgrade the wiring to a lower gauge to handle the current, or spend the bucks to purchase the 200A wiring harness (making one is easy & cheaper). Also need the 200A steel Alt mount & the beefier twisted mount that goes from the back of the Alt to the exhaust manifold. The pulley is not the same as the 60a... gotta buy the pulley to fit the 200a (I think it is the same as the 100a).
 

sgtmike3

Member
38
1
8
Location
Ohio
So, If I'm looking at the TM correctly, -24P, the 60A, 100A and Prestolite 200A are all drop in for the Basic and A1 models, while the Niehoff 200A is designed for the A2 trucks. Go figure I would find two for the wrong truck.
 

papakb

Well-known member
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Location
San Jose, Ca
Vanner makes a whole series of commercial battery balancing units that allow you to draw 12 volts from a 24 volt system. They will also work to keep the batteries balanced so you don't kill one before the other . Here's a link to their website: http://www.vanner.com/manuals/65-80.pdf These units come in 60 and 100 amp sizes that should be enough for what you need.

Kurt
 
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