Military Cutoff Disconnect Switch HMMWV Battery

[Mogman]

Mogman I think that’s the point lol……I want to cut everything off when I use the switch.


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Then you have to have two switches or a dual switch.
If you break the connection between the batteries and leave the 12v connected to the high side battery (neg) you have the exact same situation you had when you disconnected the ground side of the low side battery the 24v stuff will seek ground through the 12v equipment, if you leave the 12v connected to the low side battery everything 12V will still have power.
No way around having a dual or two switches
BTW the feed you saw illuminating lights etc were because you were causing a reverse polarity on the 12V connections, this can cause damage to the 12V electronic equipment, the big hazard of just disconnecting the low side battery ground.

 

[nikojo]

Then you have to have two switches or a dual switch.
If you break the connection between the batteries and leave the 12v connected to the high side battery (neg) you have the exact same situation you had when you disconnected the ground side of the low side battery the 24v stuff will seek ground through the 12v equipment, if you leave the 12v connected to the low side battery everything 12V will still have power.
No way around having a dual or two switches
BTW the feed you saw illuminating lights etc were because you were causing a reverse polarity on the 12V connections, this can cause damage to the 12V electronic equipment, the big hazard of just disconnecting the low side battery ground.

Agree.

These are dual switches.

if you disconnect the inter battery cable there will be no way for forward battery to find ground.

the reason to use that as disconnect is it’s SLL local, ie easier to run and hookup cables to switch.

otherwise hard to extend VR cable.

 

[Mogman]

The advantage to using a ground side switch for the 24V is if any of the cable or connections accidentally finds ground it will not start a huge fireworks display.
If you use a dual switch, one on the ground side of the low side battery and one disconnecting the 12V connection between the batteries there will be no current flow anywhere, basically doing the same job as using the 24V (high current) switch between the batteries or on the positive side of the high side battery, makes no difference only breaking the low side battery ground is as I said safer.

 

[juanprado]

You have peaked my curiosity. Can you pdf and post the military kit instructions and parts break out?

Thanks!

 

[nikojo]

The advantage to using a ground side switch for the 24V is if any of the cable or connections accidentally finds ground it will not start a huge fireworks display.
If you use a dual switch, one on the ground side of the low side battery and one disconnecting the 12V connection between the batteries there will be no current flow anywhere, basically doing the same job as using the 24V (high current) switch between the batteries or on the positive side of the high side battery, makes no difference only breaking the low side battery ground is as I said safer.

Agree. That’s perfect setup I believe. Sourcing cables to do it now.

Will update with pics when done.

You have peaked my curiosity. Can you pdf and post the military kit instructions and parts break out?

Thanks!

will do

Here is a pic of the kit. Comes with the cables and switch obviously. You could easily do thiswith same parts for 1/4 the price of formal kit.

I will scan the install manual to pdf. Unfortunately won’tbe home for a week.

 

[nikojo]

Anyone know if the voltage regulator can get damaged if it goes false ground?

How would you know or test for it?

 

[Mogman]

Anyone know if the voltage regulator can get damaged if it goes false ground?

How would you know or test for it?

What do you mean by false ground

 

[nikojo]

What do you mean by false ground

When current gets pulled in reverse.

I might be using wrong terms. I’ve tried reading about this and have hard time pulling much up on google. Might be using wrong search terms.

Adding to what we were discussing. For example, rear battery ground disconnected then someone turns on lights…….light pulls current from front battery then goes through battery interconnect and to voltage regulator. That’s only way it can find ground. Nothing else connected.

Will TCM get hurt? Fuel solenoid? Wondering what can get hurt and what doesn’t?

Obviously goal is to avoid.

 

[nikojo]

You have peaked my curiosity. Can you pdf and post the military kit instructions and parts break out?

Thanks!

Juan here is link to more pics of everything in kit.

(9) US Hardware Supply 57K6230 Battery Disconnect Switch Accessory Kits

A complete inventory of all parts was not conducted.

www.govplanet.com

 

[Mogman]

When current gets pulled in reverse.

I might be using wrong terms. I’ve tried reading about this and have hard time pulling much up on google. Might be using wrong search terms.

Adding to what we were discussing. For example, rear battery ground disconnected then someone turns on lights…….light pulls current from front battery then goes through battery interconnect and to voltage regulator. That’s only way it can find ground. Nothing else connected.

Will TCM get hurt? Fuel solenoid? Wondering what can get hurt and what doesn’t?

Obviously goal is to avoid.

OK, in my world they call that reverse polarity, nothing electronic that operates on DC likes that, I would suppose the HMMWV 12V tap (the only one that can get subjected to reverse polarity) probably has some protection because everyone that is using a single switch on the ground side of their batteries and ever turns on any 24V load with that switch off subjects the 12V tap on the regulator to reverse polarity and we would likely hear more complaining about bad regulators.
I reburb Motorola radios for allot of VFD's and of course they use allot of surplus military vehicles, every return I have ever had was caused buy the 24V system finding a "false ground" through the Motorola radio connected to the 12V tap because of them using a single switch on the ground of the batteries of a surplus military vehicle.

 

[Crapgame]

You have peaked my curiosity. Can you pdf and post the military kit instructions and parts break out?

Thanks!

I scanned the 57K6230 instructions into PDF but I can't post into the MWO thread in the TM section.

 

[juanprado]

I scanned the 57K6230 instructions into PDF but I can't post into the MWO thread in the TM section.

You have to use the upload Thread then a mod will move over or send to guyfang.
You could also post here.

 

[Crapgame]

You have to use the upload Thread then a mod will move over or send to guyfang.
You could also post here.

57K6230 PDF is too large for the server to process. I emailed it directly to you as attachment,

 

[papakb]

Cole Hersee makes a DPST switch that can disconnect both batteries independently. This could be used to disconnect the main ground and then the 12v tap that powers the TCM. Would this solve your problem?

 

[papakb]

delete, duplicate

 

[TOBASH]

Cole Hersee makes a DPST switch that can disconnect both batteries independently. This could be used to disconnect the main ground and then the 12v tap that powers the TCM. Would this solve your problem?

View attachment 887734

Papa. I read the fine print… This unit is NOT continuous use as our rigs might need more than 125 amps on a continuing basis.

Maybe CamO would know more.

 

[Milcommoguy]

Cole Hersee makes a DPST switch that can disconnect both batteries independently. This could be used to disconnect the main ground and then the 12v tap that powers the TCM. Would this solve your problem?

View attachment 887734

This switch will stop all the electrons loose in the battery box at the flick of the wrist.

Switch would meet any basic Humv battery disconnect needs IMO. (Not trying to switch out an electric winch circuit) Point to what the heck draws 125 Amps. Someone running a laser beam alien defender system? LOL

Electrons safe from any unseen gremlins.

No need to remove batteries at night, CAMO

 

[Mainsail]

Does the 12V line "need" something as stout as a battery cutoff switch, or would a good military grade toggle switch do the job?

 

[Coug]

Am I missing something about how these trucks electrical system work?


It was my understanding that the 12V to the TCM was operated by a relay powered by the 24V system.

With the 24V system disconnected, wouldn't that also mean that the 12V system can't be operated either?

Or does the 12V circuit go to both the relay and the TCM directly at the same time?

 

[Mogman]

Am I missing something about how these trucks electrical system work?


It was my understanding that the 12V to the TCM was operated by a relay powered by the 24V system.

With the 24V system disconnected, wouldn't that also mean that the 12V system can't be operated either?

Or does the 12V circuit go to both the relay and the TCM directly at the same time?

I am not sure why you are asking but there is a 12V feed to the TCM that is hot all the time and a switched feed.