Battery Disconnect Quick Question

[osteo16]

I'm not sure why I opened up this can of worms.I know why, for all the input.. Gets the thinker, thinking.. The disconnect will work in theory if no other loads are connected across both batteries except main line.. Once I add either an equalizer or 24/12V converter, then I either need multiple disconnects or nothing.. Bummer, wasn't looking to make the HMMWV look like the space shuttle.. Back to the drawing board.. I don't mind leaving everything hooked up, I'll have a charger on system most of the time... Just with wife and kids driving it, I know they will leave something on and kill a battery... UGHHHH ..... There is a product from my UTV that might be viable...It will allow charging of an extra battery while not allowing any draw on the upstream batteries.. Its a one way circuit, allows charging but no backwards draw.. I could hook this to the converter, run a third battery, and worse case scenario is they don't get to have a radio, USB ports, extra lighting ect, but HMMWV will still have juice to start and run.. And battery disconnect should be viable since its a one way current through this device. HMMMM

 

[HUNvee]

How is the 57K6230 factory kit connected?

 

[Action]

My rear view camera hardwire thing completely shuts it off if the battery voltage would get down to a predetermined level. That is if it sat left on for loooong periods.
maybe there is something similar for batteries to disconnect itself if voltage got to the preset level.

 

[Milcommoguy]

Look up "CHARGE GUARD" or a " two way radio timed disconnect search". This is what I use to automatically disconnect batteries. Voltage and a timed disconnect features with manual override. Start engine or manual and it comes on line. Leave it on...times out after (you decide) saving your butt. LOL

You are just about committed to use two solenoids to break the converter / equalizer... thus removing it and any external loads. Easiest in IMO.

When rig is OFF / STOP there shouldn't be any current draw. If the large manual disconnect switch is for security, I suggest a secret switch or HIGH quality rated key ON-OFF. NOT RUN with START... single pole In line with the RUN circuit. Or space shuttle design all together with the manual MASTER DISCONNECT and launch abort switch. Basically what my radio truck set-up. It's a workable problem needing out of the box solution.

EVENSVILLE... beep.... it's a minor problem....beep, CAMO

 

[Hammer]

Camo, Yeah, a remote dual solenoid setup would probably be the best. Just not the cheapest. Easy enough to use a key for both at the same time, remotely.
My concern is with security and battery draw. I don't want someone randomly turning my power on and killing the batteries, trying to start it, etc.

A keyed neutral safety switch would keep people from starting it, but they can still leave the power on.
A fuel cutoff will let someone crank it until the batteries die. Another no-go for me.

Of course, anyone can just pop the passenger seat, swap battery cables around and steal the vehicle. But that typically takes forethought.

 

[Milcommoguy]

Camo, Yeah, a remote dual solenoid setup would probably be the best. Just not the cheapest. Easy enough to use a key for both at the same time, remotely.
My concern is with security and battery draw. I don't want someone randomly turning my power on and killing the batteries, trying to start it, etc.

A keyed neutral safety switch would keep people from starting it, but they can still leave the power on.
A fuel cutoff will let someone crank it until the batteries die. Another no-go for me.

Of course, anyone can just pop the passenger seat, swap battery cables around and steal the vehicle. But that typically takes forethought.

Can't leave the power on. It times out after a selected time.

Done and off. CAMO

 

[INFChief]

I'm not sure why I opened up this can of worms.I know why, for all the input.. Gets the thinker, thinking.. The disconnect will work in theory if no other loads are connected across both batteries except main line.. Once I add either an equalizer or 24/12V converter, then I either need multiple disconnects or nothing.. Bummer, wasn't looking to make the HMMWV look like the space shuttle.. Back to the drawing board.. I don't mind leaving everything hooked up, I'll have a charger on system most of the time... Just with wife and kids driving it, I know they will leave something on and kill a battery... UGHHHH ..... There is a product from my UTV that might be viable...It will allow charging of an extra battery while not allowing any draw on the upstream batteries.. Its a one way circuit, allows charging but no backwards draw.. I could hook this to the converter, run a third battery, and worse case scenario is they don't get to have a radio, USB ports, extra lighting ect, but HMMWV will still have juice to start and run.. And battery disconnect should be viable since its a one way current through this device. HMMMM
View attachment 846242

Let’s take a new look this. What is it you want? I may not understand.

Instead of overthinking this with gizmos, gadgets and such, can you simply secure the vehiclein a garage?

If a secure garage is not an option then there are a couple of ideas to consider.

Make sure whoever drives or operates it knows exactly what to turn off.

For added security you could chain the steering wheel. You could fab a lock for the battery box. You could isolate the starting circuit so a miscreant cannot abscond with your ride. And, or, you could isolate the accessories.

I don’t see a reason why you couldn’t isolate the starting circuit - either the heavy gauge lead to the starter or the heavy gauge lead to ground and still have accessory power. A 2 post buss connected with one heavy duty lead from the battery pack to the busd & one branch going from the buss to the starter could be isolated and the 2nd branch from the buss left energized for whatever else you need.

You could also install ignition key with a separate ‘master power switch’ just for the starter circuit. The master power allows battery voltage to go to the keyed ignition. Otherworldly the keyed ignition will not work.
Maybe I just didn’t grasp what it is you needed.

 

[Mogman]

I try to get one's thinker going. AND note everyone has their own way to skin the cat.

Pencil and paper time. Draw out the two batteries. show the front +24 volts going to the truck, the - & + strapping the two together. Add the placement of the switch on the - ground rear battery. GOOD. Move to the front of the class. No copying!

Yes, we / most can do this in our head. You got your back battery and it's ground post is connected to the shunt and down to the real ground stud which is on the starter frame bolted to the engine. SO far so good and for simplicity sake GROUND, breaking that back battery ground with the disconnect breaks the ground and all is good. This set up removes both batteries from providing 24 volts to your rig. (providing NO wonky 12 volt tap to run your 12 volt stuff) Security or safety switch all GOOD.

Where it get sideways is those making connections to the 12 Volt connection to run 12 volt equipment. If you OPEN the ground with the disconnect switch, the ground potentially now moves up to the front battery thru your 12 volt equipment. Draw that connection

With the switch OPEN in the disconnected security / safety position AND any attempt to pull a load on the 24 volts leg...say try and start, turn on the lights... the front + 12 volt battery will be the source (can't be 24 volts, the back was disconnected, right), so front -12 volt battery becomes the return or ground thru your 12 volt equipment. This configuration will likely damage the 12 volt equipment. This is the sneak - current not anticipated or a false ground return. Good chance the equipment becomes the "fusible link" and poof.

You could do the disconnect on the positive + 24 volts lead. Again a bad idea should you leave the 12 volt gear on. Now a dead rear battery requiring charging the dead one and then balancing the two. BIG pain in the butt. 60 Amp dudes, raise your hand if your arm pressing - swapping batteries to keep the 12 volts stuff working. Trying to run a QUALITY, reliable 12 volt feed using the 60 Amp system above is problematic.

I too have the 60 amp alternator set up. (and lots of radios) Your choice to use a 24 to 12 volt converter is the way to go (proper capacity/rating). Even better, one that is a battery equalizer. This way at least the two batteries are seeing a balanced charging / discharging condition.

Use best wiring practice and fusing.

Sure, BEST would be the 200 Amp alternator with the 14 volt regulator connection to batteries. To switch up could be the cats meow and big $$$.

I went with the Eaton Sure Power 100 Amp equalizer with excellent results and IMO the best answer to 60 Amp operators. Almost plug and play.

New in the box cheap. Go with what you got, CAMO

I said the same damn thing some time ago and everyone thought I was full of crap.....

 

[Mogman]

If you are going to be running a dual voltage system off of a single set of batteries you need 2 switches,one for the 24V positive and one between the center battery connection and any 12 volt load/charging leads,


despite what the left over nomenclature says the small switch is the 12V one.

I also have great reservations about any switch that can be switched with such a small key is up to the task, it takes a great deal of contact closure force for high current applications, for example this Hella switch exerts great force against the contacts with this large key using cam action.

 

[Mullaney]

I said the same damn thing some time ago and everyone thought I was full of crap.....

.
I have had that happen more times than one... Thing is, don't let it get to you. Keep saying what you are saying and eventually it will sink in.

Me personally, I have a 24v Ford box truck. Something in it somewhere (guessing the liftgate) will "vampire" the batteries in about a week. Seven days - Go! Eight days - Nope, Not Gonna Happen! No clicky, no cranky...

A couple of years ago I installed a heavy duty battery disconnect on the positive terminal. So long as I don't forget to turn the switch off it works. Disconnect seems to have pushed it to a little more than "two weeks to dead". I finally bought a second battery disconnect and put it on the negative side. Now the batteries don't drain.

I have a regular monthly run with it and that problem is over - at least for the last several months

 

[Mogman]

The problem with the "light duty" switches as shown in the first post is they will probably work fine day in and day out when everything is working normally and it only takes 2-3 seconds of cranking to get the engine started, the PROBLEM is they could fail when you need them the most, when on the shoulder of a highway trying to get primed after accidentally running out of fuel or on the trail trying to troubleshoot a no run condition where you are cranking the engine much longer than usual, etc.

That Hella switch shown above is rated at 2500A for 10 seconds!

 

[Retiredwarhorses]

Hmmm, 2 pages to install battery disconnect? Ok…
The disconnect is installed to break the ground between the rear battery ground, just as if you were
Performing electrical maintenance on the truck and removing the rear battery ground.
AFAIC, any other way is wrong…
let me add…some of you with 4 speed trucks are going to get a rude surprise after installing
a BCO, you will find that the 14v tap cable to the voltage regulator acts as a ground and even though the ground
is pulled on the rear battery….your truck will crank and wait light will come on.
this is why I know longer install BCO’s…

 

[Mogman]

Hmmm, 2 pages to install battery disconnect? Ok…
The disconnect is installed to break the ground between the rear battery ground, just as if you were
Performing electrical maintenance on the truck and removing the rear battery ground.
AFAIC, any other way is wrong…
let me add…some of you with 4 speed trucks are going to get a rude surprise after installing
a BCO, you will find that the 14v tap cable to the voltage regulator acts as a ground and even though the ground
is pulled on the rear battery….your truck will crank and wait light will come on.
this is why I know longer install BCO’s…

Again why you need two switches, one ea. in the 24V and 14V positive leads

 

[Milcommoguy]

Hmmm, 2 pages to install battery disconnect? Ok…
The disconnect is installed to break the ground between the rear battery ground, just as if you were
Performing electrical maintenance on the truck and removing the rear battery ground.
AFAIC, any other way is wrong…
let me add…some of you with 4 speed trucks are going to get a rude surprise after installing
a BCO, you will find that the 14v tap cable to the voltage regulator acts as a ground and even though the ground
is pulled on the rear battery….your truck will crank and wait light will come on.
this is why I know longer install BCO’s…

The design of the HumV 24 Volt system has a "devil in the battery box" The laws of electricity and the spoken word this Sunday from CAMO and witness by RWH. Today"s word is "TAP"

I have said this over and OVER, explained, drawn pictures, asked for owners to draw it out to see for themselves ...

It may seem simple... AND it would be ALL things being 24 Volts. When the need to supply the 12 Volts by TAP is when electrons start going in unwanted directions.

Simple thinking caps on for those in the front row pews.

TAP is the clue word as in water. Think of this as a water source in these magical batteries from another world. (not going to deal with the electrons yet.)

Each battery has a pressure of 12. Two batteries 12 + 12 = 24. If a connection is OPEN the water will not flow out.

Pressure can come from both ways to the 12 TAP. Ideally it would be balanced with 12 at the TAP and 24 to the truck front battery with the back battery grounded. You do have then installed that way ? Another black mark it the BIG BOOK if not.

Remember these are "magical battery" filled with holly water. Just believe it. I am sure I'am going some place bad after this.

Open the connection on the back battery (the ground) ... no water flow.... BUT the TAPPED connection has the potential to become the new ground.

Completing the path or flow from the front battery, should an operator attempt to (make any 24 connection) to the front battery. ie start, lights, honk, stop etc. A REVERSE FLOW is in effect back thru the TAP and associated equipment to ground. IE transmission control, radio, etc.

Substitute pressure with electron, so we need them going in the right directions. If one provides a TAP...That can become a two way street.

We know electronics are not happy with reverse current flow... electricity or water. LOL (and this could be a hint to failed "box" failures)

You say "I am smarter than the average bear" say it loud. I will disconnect the front battery and there! Done with it. OK... Leaving the 12 Volt stuff on and killing the back battery....NO Heaven NO anywhere. How many have done that.......... Do I hear an AMEN.

When one "half taps" the batteries one is going to have to open both ends of the circuit in these HumV's to eliminate any chance of a return path draining the rear battery or pulling a reverse current thru your fancy 12 volt equipment and damage (4l80 transmission parts too). Couple of ways... leave the TAP floating, another water term, OR break any two connections completely. Break the flow...Save the POWER

Do a little homework. Get your multi-meter out and use it ... to verify leakage, sneak currents and the like. It can be a devil of a problem.

There are duel disconnects >> It's only 90 bucks in the HumV collection basket to do the right thing. LOL Race cars need to disconnect EVERYTHING.

Moroso 74108 Moroso Battery Disconnect Switches | Summit Racing

Free Shipping - Moroso Battery Disconnect Switches with qualifying orders of $109. Shop Battery Disconnect Switches at Summit Racing.

www.summitracing.com

Or two contactors / solenoids (cheaper) or a double pole jobbie (expensive) or the manual one above. Don't over think it. The one above will handle it... short of some BIG ASS winch running thur it. Now I am in trouble. Design at your own needs.

If the manual DUEL disconnect is for maintenance Great. Security build / put a lock box on it. If they want the rig that bad...sleep in it with S&W.

Praying this goes away too. Holly Smokes, CAMO

Enjoy your day....................

 

[Mullaney]

The design of the HumV 24 Volt system has a "devil in the battery box" The laws of electricity and the spoken word this Sunday from CAMO and witness by RWH. Today"s word is "TAP"

I have said this over and OVER, explained, drawn pictures, asked for owners to draw it out to see for themselves ...

It may seem simple... AND it would be ALL things being 24 Volts. When the need to supply the 12 Volts by TAP is when electrons start going in unwanted directions.

Simple thinking caps on for those in the front row pews.

TAP is the clue word as in water. Think of this as a water source in these magical batteries from another world. (not going to deal with the electrons yet.)

Each battery has a pressure of 12. Two batteries 12 + 12 = 24. If a connection is OPEN the water will not flow out.

Pressure can come from both ways to the 12 TAP. Ideally it would be balanced with 12 at the TAP and 24 to the truck front battery with the back battery grounded. You do have then installed that way ? Another black mark it the BIG BOOK if not.

Remember these are "magical battery" filled with holly water. Just believe it. I am sure I'am going some place bad after this.

Open the connection on the back battery (the ground) ... no water flow.... BUT the TAPPED connection has the potential to become the new ground.

Completing the path or flow from the front battery, should an operator attempt to (make any 24 connection) to the front battery. ie start, lights, honk, stop etc. A REVERSE FLOW is in effect back thru the TAP and associated equipment to ground. IE transmission control, radio, etc.

Substitute pressure with electron, so we need them going in the right directions. If one provides a TAP...That can become a two way street.

We know electronics are not happy with reverse current flow... electricity or water. LOL (and this could be a hint to failed "box" failures)

You say "I am smarter than the average bear" say it loud. I will disconnect the front battery and there! Done with it. OK... Leaving the 12 Volt stuff on and killing the back battery....NO Heaven NO anywhere. How many have done that.......... Do I hear an AMEN.

When one "half taps" the batteries one is going to have to open both ends of the circuit in these HumV's to eliminate any chance of a return path draining the rear battery or pulling a reverse current thru your fancy 12 volt equipment and damage (4l80 transmission parts too). Couple of ways... leave the TAP floating, another water term, OR break any two connections completely. Break the flow...Save the POWER

Do a little homework. Get your multi-meter out and use it ... to verify leakage, sneak currents and the like. It can be a devil of a problem.

There are duel disconnects >> It's only 90 bucks in the HumV collection basket to do the right thing. LOL Race cars need to disconnect EVERYTHING.

Moroso 74108 Moroso Battery Disconnect Switches | Summit Racing

Free Shipping - Moroso Battery Disconnect Switches with qualifying orders of $109. Shop Battery Disconnect Switches at Summit Racing.

www.summitracing.com

Or two contactors / solenoids (cheaper) or a double pole jobbie (expensive) or the manual one above. Don't over think it. The one above will handle it... short of some BIG ASS winch running thur it. Now I am in trouble. Design at your own needs.

If the manual DUEL disconnect is for maintenance Great. Security build / put a lock box on it. If they want the rig that bad...sleep in it with S&W.

Praying this goes away too. Holly Smokes, CAMO

Enjoy your day....................

.
Well worded CAMO!
The security fix works really well too!

Your writeup explains a lot - if people will just take a minute and understand.

 

[Mogman]

I was just curious so I inquired to Pollak the following:

" On your part number 51-916EP you say 1000A surge, how many seconds of "1000A surge" is it rated for? Thanks"

This was their response:

4 seconds on, 20 minutes off.
Stephen Tacchi
Aftermarket Sales Manager – Pollak Products
Standard Motor Products Inc.

 

[ToddJK]

I don't own the same vehicle, but my deuce has a battery disconnect hidden in the cab. I forget to switch it off a few times too many and after a couple days of not running the truck, the batteries are weak, almost dead. I'm pretty sure I have some hunting to do to find what is drawing a low current, but for the mean time, and added security, I was going to add another disconnect switch on the dash. I'm also going to install a 1/4" red indicator light that will power from the disconnect when the power is on so I will see the truck has juice. This will go on the pos cable. The other disconnect is on the pos cable as well but I'm going to switch it over to the neg cable once my wire comes in. One should do, but since I prefer to not have a keyed ignition or anything, the added security and peace of mind is worth it to me. This way in the future if I do add some 12v accessories, then I know nothing in the truck can have any power if both disconnects are shut off. The idea of the indicator light is mainly a reminder for me so I won't forget to shut off the power supply in the future. I'm just going to use the pre-existing holes in the dash where the fire extinguisher usually goes or the weapon mount, there are smaller and larger plugs in these holes. Not gonna be pretty or professional looking, but it'll be decently clean and function. I'll post some pics once I get around to it.

 

[Action]

Looking at the title, was this supposed to be a quick question? Or a question about quick disconnect?
i had mybattery cover off yesterday and realized we were all over thinking this. Talking about backfeed through 12v items....if you put both 12v and 24v grounds on the same side of the switch, and the rear battery on the other side, wouldn’t that prevent any backfeed issues?

 

[Coug]

Looking at the title, was this supposed to be a quick question? Or a question about quick disconnect?
i had mybattery cover off yesterday and realized we were all over thinking this. Talking about backfeed through 12v items....if you put both 12v and 24v grounds on the same side of the switch, and the rear battery on the other side, wouldn’t that prevent any backfeed issues?

I think the thought that was somehow the power would go from the negative of the first battery and use the 12V stuff for the electrical to find it's way back to the positive side of that battery.
I have no idea how that would work anyway.

All I know is, with my battery disconnect between the DC shunt and the rear battery negative post, I have ZERO power at anything in my truck. Zip, Zilch, Nada.

Now, if someone added a bunch of 12V crap connected straight to the rear battery, then maybe it might lead to issues. As setup stock though, the 12V should be going through a relay that is activated by the ignition switch, so if the switch isn't on, then no relay and no 12V power.

It was mentioned that the dual voltage regulators have a 14V tap, but by their very nature, shouldn't a properly functioning generator system have diodes in it to only allow voltage to flow one direction? Of is the bridge rectifier thingy only in alternators and not our DC generators?

 

[ToddJK]

I don't run any 12v accessories. I try to keep it all 24v. As far as I know, the better way to run 12v stuff, is too have a third battery that is charged by a 12v alternator that's added to the truck. My buddy had a system like that along with a power inverter or some type of power bank added, he didn't have any issues. Not that I know of. I haven't talked to him in years so that remains to he unknown. For the disconnect, I have one on the negative cable and one on the positive cable. Mostly a redundancy and also added security as most people won't think to look for 2 disconnects. If I was going to run any 12v accessories off one battery, I would probably add an extra disconnect just for the 12v accessories just to be on the safe side. As I recently added another, I mentioned in a previous post I added an indicator light just so I knew the batteries were connected to the truck and the truck had power regardless if the accessory switch was on or off and I used all pre-existing holes in the dash.