Converting 24volt to 12 volt M1009 CUCV

[NMC_EXP]

Sidebar question:

If a person put an ammeter in the starter cable could that data be used to back calculate actual starter power draw?

I find this stuff interesting. To me, electricity is in the same family as magic.

Regards

Jim

 

[NMC_EXP]

"My personal theory is that the voltage drop in the main starter wire is not as much on a 24v system. You're not having to try and "push" as many amps on 24v as you do with 12v to get the same amount of work done."

I think that is one of the three legs of the Ohns Law tripod. Amp draw goes up, resistance goes up.

Regards

Jim

 

[watkinssr]

Sidebar question:

If a person put an ammeter in the starter cable could that data be used to back calculate actual starter power draw?

I find this stuff interesting. To me, electricity is in the same family as magic.

Regards

Jim

yes. You'd want to use a clamp on ammeter, I would imagine. But you could read the actual current draw.

Mind you, the current draw I posted was free spinning, no load. The actual current draw when turning a motor will be a whole lot more than that.

 

[NMC_EXP]

yes. You'd want to use a clamp on ammeter, I would imagine. But you could read the actual current draw.

Mind you, the current draw I posted was free spinning, no load. The actual current draw when turning a motor will be a whole lot more than that.

Had I not been "encouraged" to retire early I'd borrow the gear from work and check it out.

All I have is a cheapo little chicom made multimeter so I guess this will remain unanswered.

Regards

Jim

 

[amphi]

The engineers did a brilliant job at creating this.

I agree !!

This system has the ability to service either or both batteries and the vehicle load based on-demand. It seems to be a good alternative when compared to the expensive battery equalizers like the one liked below:

ANALYTIC 50A, 24V, (VOLTAGE IN / 2), BATTERY EQUALIZER

See my article in the August issue of Military Vehicles Magazine.

Gary

 

[watkinssr]

Had I not been "encouraged" to retire early I'd borrow the gear from work and check it out.

All I have is a cheapo little chicom made multimeter so I guess this will remain unanswered.

Regards

Jim

Yeah, it would fry a mutlimeter.

 

[doghead]

If your interested, here's a "based on experience" comparison.

Here in NY, In the 80's, it seemed that all civilian 12v diesel Chevys(new then), either would need a jump or needed to be plugged in, to start in the wintertime.

In the last 2 winters, my M1008 with 24v starter, starts ever single time and starts as good (fast) as my modern(2000) gas fuel injected truck.(other than the GP wait time)

I have resupplied the GPs with 12v, to eliminate the one fails they all fail, issue with the GPs. GPs do go bad, that's just a fact of life.

I see no reason to convert to 12v, It would be a bad choice for me(for sure).

 

[2deuce]

Doghead, did you bypass the resistor to eliminate the glow plug problem? From what I can see the resistor is the problem with the glow plug system.

As for converting to 12 volt the only reasons I can see is if your 24 volt starter goes bad and you already have some 12v starters or you want to add an air compressor where alt #1 sits.

 

[doghead]

Doghead, did you bypass the resistor to eliminate the glow plug problem? From what I can see the resistor is the problem with the glow plug system.

I have resupplied the GPs with 12v, to eliminate the one fails they all fail, issue with the GPs. GPs do go bad, that's just a fact of life.

Yes, I simply removed the original red wire at the GP relay(taped the end over). Then I made a new wire and installed it on the GP relay and the other end is on the 12v stud above the GP relay.
If I ever have a totally dead front battery and only have a mil vehicle to slave start with, I can just reconnect the original setup(disconnecting my modification first of course).

I have seen Dealer installed AC on cucv's with the stock dual alts. It can be done.

 

[Recovry4x4]

I agree !!

This system has the ability to service either or both batteries and the vehicle load based on-demand. It seems to be a good alternative when compared to the expensive battery equalizers like the one liked below:

ANALYTIC 50A, 24V, (VOLTAGE IN / 2), BATTERY EQUALIZER

See my article in the August issue of Military Vehicles Magazine.

Gary

Enjoyed your article Gary, thanks!

 

[BIG_RED]

If you need 12 volts, you have 12 volts. Essentially, you have an old GM truck with a 100 amp 12 volt alternator to run 12 volt stuff to your heart's content. AND you have another 12 volt alternator, for extra stuff. You CAN get 12 volts from alt2 using the original wiring system, just use +12 as (-) and +24 as (+). THIS IS DANGEROUS ON NEGATIVE GROUND EQUIPMENT UNLESS IT IS ISOLATED PROPERLY. My second alternator does nothing after the battery recovers from starting my engine, so I have an extra 100 amps of free power over a normal Chevy truck. I have ALOT of isolated ground lights, heated seats, and auxiliary electric heater (instant cabin heat in winter, no waiting for coolant to warm up) and a 12 volt inverter mounted on pieces of ceramic (to isolate from vehicle ground) that all runs off my "extra" alternator, PLUS a TON more stuff that runs of the normal 12 volt side of the system. A new 24 volt alternator is like $100 on ebay. I take excellent care of my batteries, so I never have to worry about one dying, etc. Sure, if you had a 12 volt starting system, you could receive a boost from a civvy vehicle.. but you'd probably almost kill the civvy vehicle with such huge power demands on it's battery and alts. In my truck, I have no trouble starting in cold temps with 24 volts. My friends with 12volt diesels can't say the same. I go around boosting everybody off my batt2. Just don't let the vehicles touch and connect both cables to batt2 and don't touch the body with them. There you go, another handy use for your second 12 volt system, boosting friends without worrying about discharging your main battery, with no danger of voltage spikes frying your radio.

When it comes to high power demand, more voltage = more better. That's why cross-country power lines run like 230,000 volts. Ohms law shows half the resistance (lost power) in 24 volt system compared to 12 volt. That's half the power lost in the wire, worn solenoid terminals, even the brushes of the starter itself. (power losses you can't even measure unless you take apart a spinning starter) Not to mention how more voltage performs better in electromagnetic electric motors..

As was said, your truck, your call. I just want to make it clear to others considering a 12 volt conversion - you are no further ahead, and if cold weather is a factor - 24 volt is MUCH MUCH BETTER.

Even if you want a compressor under your hood.. I could do that with 2 alts no problem. Just put the compressor / generator / etc. in the empty void above the steering stuff on the driver's side, and run a jackshaft to the front of the engine with a pulley to a slightly longer alt1 belt.

I love my 24 volt truck. Wouldn't change it. Just my .

 

[btrapr]

great thread_________I am still trying to figure the system out on my 1008...I do not want to do a 12v conversion BUT I am very interested in going to 12v GP's, and hooking up some 12v accessories.

24V slave plug- How do you re-wire this as my 1008 is there but not connected! The dust cover is also missing? Where can I find one?
Thanks

K9Vic
The 24v/12v system on the other CUCV is safe and you can run 12v accessories on the 12v side of the battery.

I have installed 12v lightbars on multiple CUCV trucks, radios and 12 accessory jacks for GPS and other 12v accessories. There is no need to make it 12v, these are native 12v with a 24v starting system.

Could you elaborate on this for me! asI too want to add some 12v accessories…Do you have any pics where you hook up to…I was thinking about adding a three-five fuse block under the hoos to safely power a few things
Doghead
Can you elaborate? Pics?
Yes, I simply removed the original red wire at the GP relay(taped the end over). Then I made a new wire and installed it on the GP relay and the other end is on the 12v stud above the GP relay.
If I ever have a totally dead front battery and only have a mil vehicle to slave start with, I can just reconnect the original setup(disconnecting my modification first of course).
thanks in advance!

 

[NMC_EXP]

As was said, your truck, your call. I just want to make it clear to others considering a 12 volt conversion - you are no further ahead, and if cold weather is a factor - 24 volt is MUCH MUCH BETTER.

This may be true but I have not seen any hard data to back up this assertion, only anecdotal info. When I say hard data I mean controlled testing as in actually starting an engine in a cold room with 24V vs 12V starting systems and measuring things such as cranking speed and cranking time until the batteries are discharged to the point they will not turn the engine fast enough to start it.

Delco Remy may have done this type of testing. The DoD almost certainly has.

If it is true, and I suspect that it is, how much better is 24V? Is a poorly maintained 24V starting system better than a well maintained 12V? The list of variables which affect starting is long. Too long for me to lose sleep over.

One factor which holds true no matter what sort of system you're talking about is that simple systems are more reliable than complicated systems. The K.I.S.S. Principle is actually backed up by science and engineering.

If a system has four components and each individual component has a reliability of 0.9 (90%), then the overall system reliability is:

0.9 x 0.9 x 0.9 x 0.9 = 0.6561 (65.61%)

If a system has two components and each component has a reliability of 0.9 (90%) then the overall system reliability is:

0.9 x 0.9 = 0.81 (81%).

My objective is overall reliability, not just starting under unusual conditions, and the 12V system is simpler than the 24V.

If I lived in Montana and cold starting was my major concern, things might be different.

Regards

Jim

 

[Westech]

Just do it and get it over with. Hack away.

 

[NMC_EXP]

Just do it and get it over with. Hack away.

1. It's done.

2. No hacking was involved.

3. If you have some sort of personal problem, either see the Chaplain or discuss it with me like a rational adult.

Regards

Jim

 

[doghead]

Do not get personal, posting in the forums(good humor excepted).

NMC, are you going to document and share your conversion? It may be helpful to others that choose to do the same. We would appreciate your effort and time to share this.

 

[Westech]

un clamp your rear cheeks there bud.

 

[NMC_EXP]

Do not get personal, posting in the forums(good humor excepted).

That applies to all, I assume.

NMC, are you going to document and share your conversion? It may be helpful to others that choose to do the same. We would appreciate your effort and time to share this.

I can do that if you think it will not upset the purists too much.

By way of explanation - I hate to see a classic vehicle whether commercial or military, modified/bastardized.

I had an M37-B1 and everything I did on it was geared to restoration.

As I see it, the CUCV is just a stripped down commercial model with a 24V charging/starting system added on. You could take a commercial GM and convert it to a CUCV. In other words, it ain't nothing special.

Also, the Roscommon conversion is fully reversible. I will keep the parts removed and they will sell with the truck assuming I don't drive it into the ground.

Regards

Jim

 

[NMC_EXP]

un clamp your rear cheeks there bud.

I have a better idea - you don't push me, and I won't push you.

Regards

Jim

 

[doghead]

I do try to apply the rules equally to all.


If you will thoroughly post how you did your conversion, I am sure it will be useful and appreciated by many readers on the site.

If your post upsets the "purists", they can simply ignore the thread.(I will remove any negative comments so you can create a useful and informative thread).

I'd simply start with, "here's what I chose to do and how I did it. If you don't like the idea of converting to 12v, please don't argue the point here, that is not the intension of this thread".


Westy, go to your corner....