Military Cutoff Disconnect Switch HMMWV Battery

[SmartDrug]

I appreciate your help with this. I have a much better sense of the electrical system now.
Regarding the switch, I’ve seen a handful with the same specs but different model numbers. I think I’m going to call Hella tomorrow to clarify.

I’m also going to take this opportunity to remove the slave port and the rear shelter power plug to clean up the box a bit.

 

[nikojo]

In your diagram you can wire it so you cut off the 'green' and leave the "blue" alone or as Mogman pointed out do it the opposite way. That effectively does the same thing assuming you cut off both switches. I like doing it my way by cutting off the interconnect between the batteries in case I added other 12V circuits in the future. That way I don't have to add any more to the switch.

The switch I used is 2 switches in one so it does it all together.

 

[Chadwickadam]

Hey, I'm new here and this thread has been extremely helpful so thank you. I was wondering if anyone has tried this or knew the answer:

If you do the same setup as nikojo with a single dual pole switch but instead of interrupting the ground and battery interconnect, can you interrupt the ground and the opposite batteries hot?

If so, does this achieve the goal of total power shut off so nothing comes on?

Are there concerns with having the interconnect joining the two 12v batteries and then battery 1 hot and battery 2 ground going to the separate circuits of the cutoff switch?

Would I then attach the "out" pole from the switch to the hot and ground of the starter?

Thanks for the help

 

[Mogman]

Hey, I'm new here and this thread has been extremely helpful so thank you. I was wondering if anyone has tried this or knew the answer:

If you do the same setup as nikojo with a single dual pole switch but instead of interrupting the ground and battery interconnect, can you interrupt the ground and the opposite batteries hot?

If so, does this achieve the goal of total power shut off so nothing comes on?

Are there concerns with having the interconnect joining the two 12v batteries and then battery 1 hot and battery 2 ground going to the separate circuits of the cutoff switch?

Would I then attach the "out" pole from the switch to the hot and ground of the starter?

Thanks for the help

Yes interrupting the ground and 24V hot would do the same thing, no current could flow in any circuit.

 

[nikojo]

Hey, I'm new here and this thread has been extremely helpful so thank you. I was wondering if anyone has tried this or knew the answer:

If you do the same setup as nikojo with a single dual pole switch but instead of interrupting the ground and battery interconnect, can you interrupt the ground and the opposite batteries hot?

If so, does this achieve the goal of total power shut off so nothing comes on?

Are there concerns with having the interconnect joining the two 12v batteries and then battery 1 hot and battery 2 ground going to the separate circuits of the cutoff switch?

Would I then attach the "out" pole from the switch to the hot and ground of the starter?

Thanks for the help

The problem with this is that the 'high' side battery (running 12V) can still find ground through the voltage regulator.

Steven (RWH) pointed this out earlier in the thread.........."connection to the 14v tap off the regulator can and will also act as a ground when the ground is disconnected allowing the truck to be cranked over but on 12v only".

I would recommend cutting off the negative of both batteries, ie interconnect on low side battery and ground on high side battery.

If you do that there is no way for anything to get power.

But if you cut off the positive side on the first battery it will also accomplish same thing and isolate the battery bank.