Battery Kill Switch

[patter69]

Battery kill switch on negative or positive from batteries?

 

[Coug]

usually on negative. Especially if you have a dual 12/24 system.
I've seen it argued to do it either between the batteries or on the positive side, but I've always disconnected ground wires for working on stuff, due to the possibility of arcing with a misplaced wrench.

The manuals also talk about disconnecting ground before working on the truck, which for us means the negative.

 

[frauhansen]

A classic kill switch at the battery terminals yes... on the negative site. BUT.. ich you like tu use a switch outside of the battery box you have to use the positive site. Simply because the grounding happends most of the time in many different ways so you can not switch it off in 100% of all cases.

 

[Coug]

A classic kill switch at the battery terminals yes... on the negative site. BUT.. ich you like tu use a switch outside of the battery box you have to use the positive site. Simply because the grounding happends most of the time in many different ways so you can not switch it off in 100% of all cases.

Can you explain this to me? I am unaware of how a circuit can be grounded if you completely disconnect the ground side of the circuit.

I have heard of people claiming the 12V side can potentially allow reverse flow current, but unless there are aftermarket additions to these trucks, the 12V should be disconnected by a relay whenever the ignition switch is turned to off.

I would also expect that the positive side would be more dangerous to make remote location due to the fact that if a wire gets damaged in any way, the power will arc to ground in a spectacular fashion, potentially burning down the entire vehicle, where if the negative gets shorted to ground absolutely nothing happens other than your disconnect is now non-functional.

 

[frauhansen]

This only applies to the switch if you do not have it directly on the battery bay. So somewhere outside the box.
Here it has proven a positov terminal to the switch and then back to the actual distribution point in the battery box to pull.
And yes, this also works with the negative terminal.
It was explained to me that in a vehicle you basically try to have ground available everywhere with every component. Quasi a mass inflation!

But... the longer I think about it now, I think it really does not matter. What I learned seems to me as logical as illogical for a switch to negative as a switch to positive.

Translated with www.DeepL.com/Translator (free version)

 

[Coug]

This only applies to the switch if you do not have it directly on the battery bay. So somewhere outside the box.
Here it has proven a positov terminal to the switch and then back to the actual distribution point in the battery box to pull.
And yes, this also works with the negative terminal.
It was explained to me that in a vehicle you basically try to have ground available everywhere with every component. Quasi a mass inflation!

But... the longer I think about it now, I think it really does not matter. What I learned seems to me as logical as illogical for a switch to negative as a switch to positive.

Translated with www.DeepL.com/Translator (free version)

Yes, every component goes to ground, but then all of those grounds end up going to a single point, and then to the negative battery post.

Either way, the start of every circuit comes to a single point, and the end of every circuit goes to a single point. Disconnecting either of those will have the same basic effect on the system, which is to prevent any power from flowing. So in that sense, no, it does not really matter.

In a house, we kill the incoming side/source of the power, as the ground/earth is distributed and available everywhere, but in a DC circuit in a vehicle both the beginning and end are single points, so killing the one that won't cause damage if something bad happens makes more sense to me.

One more thought. To install a disconnect on the positive side of the circuit, you still have to disconnect the negative terminal from ground/earth before working to prevent accidentally causing sparks/arc welding wrenches to the body, but if you install it to the negative you don't have to disconnect the positive as well.

 

[Mogman]

This topic has been covered MANY times, Neg is the easiest and safest to do BUT if you have equipment on the 12v tap you can reverse polarity the 12v equipment including the voltage regulator, this also has been explained several times, SO I always put in 2 switches one for the neg lead and one for the 12V tap and you need the main (neg) switch to be rated at 1000A certainly not those puny little ones with the regular type key, turn the 12V tap off first and on last.

This is an example of a real switch.

I actually flipped this switch so it is connected by pushing down on the inside, the handle is 180 deg out from this picture touching the floor, this makes it much harder for the Commander to accidentally turn the switch off. I put the 12V switch The ones most think is good enough for the main switch on the 45 deg area above the main switch.
Found the final setup, despite the markings the top switch it is the 12V tap, these are both in the ON position.


Now even that puny top switch will work for day in and day out as the main switch when you only have to crank for a few seconds but when you are having problems and have to do some extended cranking it will smoke, and that is EXACTLY when you do not need something to fail.

And of course the main has a key that can be easily removed, I can assure you no one can "jimmy" that cam switch.

If you have a dual voltage system and put a switch in the positive lead you do not have the capability to shut off the 12V equipment so again you would need two switches so you may as well do the neg. lead and 12V tap as the end result is the same and you do not run the risk of having the main switch get grounded somehow.