Electrical add ons

[Brutusdog]

I would like to install a power inverter in my "new" CUCV. What recommendations are out there? Which battery would be best to hook into? I think I want to mount it under the dash, is that bad?

Also, I would like to put in some additional DC items like a radio, cb, power outlets (for GPS, Cell phone charger). Would it be better to add a new power distribution block or try to add the new items to the existing fuse block?

If I add the power block, which battery should I use? Any help would be great.

Thanks

 

[3dubs]

Which battery? The only battery for 12V is the front battery. If you tap into the rear battery you will have a fire to deal with. You may see if you can get 24V inverter. Many large RV's are 24V as well as the big rigs. So they are out there. Then you could use the power stip for the military radio. As far as other DC do a search of "cigarette lighter" and you will find threads. I just tapped into the front battery and bypassed the fuse box for my cigarette lighter. That is up to you. But if you do add an inline fuse that you have easy access to.

 

[Brutusdog]

Thanks for the info. What would cause a fire from the rear battery? Where is the power strip that you mention? I am sorry to ask so many questions, I am new to all this.

Thanks!

 

[Crash_AF]

The rear battery is 24V and a 12V inverter will burn up from the over-voltage.

Later,
Joe

 

[Westech]

you don't need a inverter in a cucv.... you know that its all 12V inside right? the fuse block is all 12V but one fuse and that is marked. You have 12V and 100 amps continuous ready.. no need for rewire the truck there guys.

 

[Brutusdog]

inverter

My reason for wanting an inverter is to power AC items. Lights, laptop, TV, etc. So, from what I understand, the front battery will give me 12V , back (closest to the firewall) will give me 24V due to them being wired in series. I just need to find an inverter that matches the voltage. Issued one solved!

 

[LEW6X6]

You can also use the junction block just above the glow plug relay to get your 12V. This j block is protected by a fusible link to help protect. Please remember that the LH alt. charges the fron battery and the RH alt. charges only the back battery (able to do this by isolated ground), so it is very important to practice load management and not put undue strain on the LH alt. Google Roscommen equipment and you can find the procedure to convert your CUCV to 12V only if you want. The Forest Service has researched this for those VFD's that can't deal with 24V.

 

[4bogginchevys]

the 12v batt is closest to the core support......not the fire wall! This may be why you've had an issue

 

[3dubs]

If you have a M1009 some have the strips on the pasenger side by the back seat for the military radio. This is 24V and prime for RV things like a refridgerator. It is also very easy to get access to, but it is 24V. My glow plug relay was changed out and a 12V wire run to it from the front battery. So I just attached a wire there and ran it in through the hole for the speedometer cable. It was faster than the fuse box. Because most auto stuff is 12V it is not hard to get. I like options so have both 12V and 24V just makes me happy. I will also add an inverter. I want a 24V inverter because I want to use the 24V power strips so they have a porpose in life.

 

[Brutusdog]

power strip

All I have back there are two screw holes. I Stuck a volt meter on it and got nothing. Can I activate it some how?

 

[Sgt Hulka]

One of the reasons I converted to pure 12V was to run a 2000 watt inverter. I mounted it under the passenger seat of my M1009 and run 4 gauge cables to it from the terminal block mounted on the right side of the interior just above the rear seat level. The plug side of the inverter faces out to the right from under the passernger seat. I retained the two alternators and added a third, deep cycle battery. In essence I have two isolated charging systems, one for the vehicle and one dedicated to the third battery and inverter. A side benefit is I have a spare battery and alternator at the ready for vehicle charging and operation.

 

[moleary]

you don't need a inverter in a cucv.... you know that its all 12V inside right? the fuse block is all 12V but one fuse and that is marked. You have 12V and 100 amps continuous ready.. no need for rewire the truck there guys.

An "Inverter" switches DC over to AC... You're thinking of a "Converter" which converts 24V DC to 12V DC. He wants an inverter.

I didn't know that a CUCV had a 12V power source - very cool and good info - thanks!

 

[jsrovers]

My reason for wanting an inverter is to power AC items. Lights, laptop, TV, etc. So, from what I understand, the front battery will give me 12V , back (closest to the firewall) will give me 24V due to them being wired in series. I just need to find an inverter that matches the voltage. Issued one solved!

Sounds like an episode of "Pimp My Ride" to me

 

[mistaken1]

All I have back there are two screw holes. I Stuck a volt meter on it and got nothing. Can I activate it some how?

There should be a 24V bus on the passenger side firewall. From there you should have wires running to the passenger compartment (passenger side) under the radio mounting shelf. There are two busses there (positive and negative at 24VDC). (See attached picture)

The positive of the front battery is connected to the negative of the rear battery (series circuit) so that you have 24VDC from the negative of the front battery to the positive of the rear battery.

The negative of the front battery is grounded to the vehicle chassis. So if you read from the positive of the front battery or negative of the rear battery (electrically the same point) you get 12VDC. However if you read from the positive of the rear battery to the vehicle chassis you get 24VDC.

If you mount electrical equipment inside the vehicle that has metal parts that bond to the vehicle chassis then the metal parts of that equipment are at the same potential as the vehicle chassis. Typically this electrical equipment is designed for a negative ground system which means that the negative input lead of the equipment is electrically bonded to the equipment chassis (which electrically bonds to the vehicle chassis).

What does this mean? It means that if you connect the positive input lead of your electrical equipment to the positive of the front battery (or negative of the rear battery) then that equipment sees 12VDC and it is happy. However if you connect the positive input lead of your electrical equipment to the positive of the rear battery and the negative input lead to the negative of the rear battery then that equipment sees 12VDC between its input leads but it sees 24VDC between its positive input lead and its chassis ground. It also means that the positive of the front battery is now shorted to the vehicle chassis ground through your new piece of electrical equipment (think homemade arc welder) and now nobody is happy except the manufacturer of that equipment because now you will be buying a replacement piece of equipment (among other things).



I installed a #6 copper conductor from the negative of the rear battery to the passenger compartment of my M1009 and mounted a third bus under the radio tray. I ran this through a 30A-20KAIC rated fuse and holder (water resistant). This way I can power my commercial radios by connecting between this third bus and the original negative bus (the one electrically bonded to the vehicle chassis). Each radio gets its own inline fuse to protect it and its input wires. (the picture was taken before this third bus was installed)



If one tried to use the rear battery by providing a metal mounting frame isolated from the vehicle chassis by a suitable insulator for a piece of electrical equipment to mount on. Then this metal mount would have to be bonded to the negative of the rear battery so that when the equipment is powered from positive and negative terminals of the rear battery the equipment will see 12VDC and the equipment chassis and negative input lead will be a the same potential so that the equipment does not act like the welding rod of an arc welder. However this is quite dangerous as this isolated metal mount and electrical equipment would be 'hot' with respect to the vehicle chassis (a meter reading from the metal chassis of the equipment to the metal chassis of the vehicle would show 12VDC) and would present some serious shock/arc/fire hazards. So this should never be done!

Technically the original military 24VDC bus and my third 12VDC bus present these same shock/arc/fire hazard but the 'hot' parts are limited to buses that are covered to prevent accidental shorting between them and the vehicle chassis. In the case of a radio or inverter the entire chassis of this equipment would be 'hot' (as well as the mounting frame) and it is harder to cover/protect this from inadvertent grounding to the vehicle chassis.


Your best bet to use the existing military 24VDC buses would be to get a 24VDC input inverter. If you are going 12VDC then stick to the front battery.

 

[Brutusdog]

power strip

My M1009 does not have the power strip in the photo. There are just two threaded holes. No rack either.

 

[mistaken1]

You can see the black plastic wire harness coming up from the floor. The wires follow the frame forward and come up the firewall to the 24VDC bus on the firewall. You should have the bus on the firewall.

 

[Recovry4x4]

It really all depends on your current needs. If you wanted to run a 2000W inverter, I'd probably go with a 24 to 120 unit so that you draw across both batteries and both alternators. A super heavy current draw across just the one battery can lead to a discharge over time. It's for that reason that I would prefer a 24V winch and it could be hooked up on a slave plug.

 

[Brutusdog]

So the large bus in the photos 24 volt and the smaller is 12 volt. That is very helpful. So, if I use inline fuses, I should be able to power some 12 volt lights and power outlet off the 12 volt with no problem? When I add the inverter, I'll go with the 24Volt and use the larger bus. As far as grounding, I just need to ground to the body some place, correct?

I really appreciate all the help that I am getting on this. It's nice when everyone has the same basic truck!

 

[mistaken1]

There are three buses. A +24VDC bus and a ground bus (same as chassis ground). Then you can see the red wire that comes off the negative terminal of the rear battery and runs across the back of the firewall to small diamond shaped 12VDC bus.

The 24VDC (positive and negative) have large wires from the batteries (front battery negative terminal and rear battery positive terminal), large wires to the slave outlet in the grill and large wires to the radio buses located in the passenger compartment. I have not traced it but there should be a large wire from the positive 24VDC bus to the starter. I have not traced all of the smaller wires but you can see the 24VDC wire that runs to glow plug resistor (for dropping the glow plug voltage to 12VDC).

Attached are images that show this in more detail. I ran a #6 wire through a fuse and followed the same route back to the passenger compartment to set up a 12VDC bus for radios. #6 wire is good for 60A (828W @ 13.8VDC) but I have it fused at 30A (414W @ 13.8VDC).

As you can see that wire that runs to the 12VDC bus is not very big so it would not take too much to overload it.

 

[Brutusdog]

12 volt bus

Just to clarify in my own mind. You added a 12 volt bus to the passenger compartment, by running it off the front battery positive (same as rearbattery negative), using an inline fuse near the battery. After going through the firewall, you mounted the bus on the interior side of the firewall in the passenger compartment.

That gave you the power feed for the radio, etc. inside the cab. Where do you ground the items? Is there a recommended place within the cab to do that? Do you ground each one or go back to a "centeralized ground"?

Sorry for the questions, but I know little about auto electric!

Thanks for all your help.