Battery Disconnects

[John Galbreath Jr.]

Both of my vehicles have the battery cutoff on the positive side. After a close call yesterday installing a battery in Solo, I think it would be best for it to be on the negative side. I ordered the cables and disconnect to add a negative side disconnect.

What are your thoughts and why?

 

[wont work]

I had mine that way and my auto teacher at the school suggested I not do it that way. He gave several reasons and to be honest I cant remember them but did change it over to where the only thing that stays hot is my memory wire to the computer.

After my close call at RBD last year I put a another master switch in that shuts the fuel pump off also. So I now have 2 master switches.

 

[patooyee]

Mine's positive also. But after I did it that way I thought, "What if the positive cable to the shutoff switch is what shorts?" Then you're still just ****ed. I would switch the negative if I did it again.

There was an older thread here about this exact thing ... see if I can find it.

 

[RustyC]

I think I replied this in the older thread to but...Caterpillar puts a battery disconnect on all their machines on the negative side. I can't remember the theory behind the location. I will try to get the reason why and reply back.

 

[sandw]

I tried this on mine it will not shut down the motor if you use a one wire alternator

 

[crawlin85cj]

I can't think of a single reason why this is a bad idea other than the additional cable required. I typically run my negative cable to the chassis shortly after the battery then use the chassis for grounds or connecting grounding blocks. It almost seems like a safer way to install it since the positive cable goes dead as soon as it looses all ground path.


2010 Jim's Garage 4429
2012 Jim's Garage YJ
2013 Wide Open Design WFO

 

[matth_85]

Since electricity typically flows opposite of what your car wiring makes you think it does make sense to do it on the negative honestly. It's just hard to get your mind past that I think.

 

[TBItoy]

Mine's positive also. But after I did it that way I thought, "What if the positive cable to the shutoff switch is what shorts?" Then you're still just ****ed. I would switch the negative if I did it again.

There was an older thread here about this exact thing ... see if I can find it.

I put a 300A mrbf fuse on the hot side of my battery in case the wire going to the disconnect somehow shorts...

My main reason for a main + disconnect was to have a distribution block at the front of the truck and to be able to stop the winch in case of a stuck solenoid/runaway winch. We had a very bad experience one day when a winch stuck ON...

https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A


I also plan to put a ground disconnect at the battery in the back, so someone could kill the truck from the outside.

 

[patooyee]

My main reason for a main + disconnect was to have a distribution block at the front of the truck and to be able to stop the winch in case of a stuck solenoid/runaway winch. We had a very bad experience one day when a winch stuck ON...

If you just ran the battery ground back to the switch would it not cut battery power just as a positive would with the positive cable ran to a positive switch?

 

[TBItoy]

If you just ran the battery ground back to the switch would it not cut battery power just as a positive would with the positive cable ran to a positive switch?

Yes ...?

I'm trying to understand what you are asking, but yes, if you isolate/switch the battery ground from the chassis, then it will kill everything when off.

I basically used the battery disconnect at the front of the truck as a junction/distribution block, I could have just used a simple post or buss bar.

 

[patooyee]

Re:

Your statement about the winch seemed to indicate that a negative switch would not stop a runaway winch for some reason. But I think I am misinterpreting you now. Don't worry. :homer:

 

[zukimaster]

Y'all need to be more positive! And quit being so negative about things!

 

[Chuck19]

My main reason for a main + disconnect was to have a distribution block at the front of the truck and to be able to stop the winch in case of a stuck solenoid/runaway winch. We had a very bad experience one day when a winch stuck ON...

https://www.bluesea.com/products/5191/MRBF_Terminal_Fuse_Block_-_30_to_300A


I also plan to put a ground disconnect at the battery in the back, so someone could kill the truck from the outside.
[/quote]




What kind of distribution block are you using I have not found one that really looks like something I want to use!

I have disconnects at both of my winches just in case !

 

[TBItoy]

Re:

Your statement about the winch seemed to indicate that a negative switch would not stop a runaway winch for some reason. But I think I am misinterpreting you now. Don't worry. :homer:

OH, I got ya.

Actually, I wanted the switch at the front of the truck (specifically for run-away winch scenario), so yeah, I had to break the + side at the front, because the winch will ground through it's body.

I welded a stud to the frame for a ground lug in the front, and one in the rear by the battery (so my - battery cable is only ~8" long).

I read a lot about using the chassis for a main ground (especially for the winch) when I debated setting it up this way, but I only have a 6000lb winch and the spec on it is max 260 amp draw... hell, it's only got 6 gauge wire coming off out of it...



But yeah, in my situation, and the way I used the disconnects, I had to break + at the front, and I'm going to add a complete - break in the rear.

I used this disconnect, and will get another for the rear.

https://www.bluesea.com/products/category/Manual_Battery_Switches

 

[RustyC]

I got a generic answer back as to why CAT puts them on the neg side. Basically due to cost and and simplicity.
On both my rigs I use a disconnect on the neg side and the chassis as the ground. The disconnect switch is in reach of the driver. With the switch off you can short anything pos+ to the chassis and there is no issue at all.
I even switch everything off when then are being hauled around.

I use a CAT disconnect the part # is 7N0718 and available at you local CAT dealer. About $75 and able to handle twin starters and emergency elect/hydro steering. No way we can hurt then on a trail rig or race car.

 

[fordcontraption01]

I run two batteries on my junk wired like a diesel and I got a disconnect on both my grounds and ever had any issues.

 

[greenlion]

I recently rewired mine to cut off the negative side. Battery ground goes to kill switch and then to chassis and engine block. No ground wires connected to battery; all connected to out side of switch or chassis. Turning the switch off completely cuts out the ground circuit, isolates the battery and kills EVERYTHING. Safest way to do it.

 

[John Galbreath Jr.]

Follow up. I already had a positive disconnect and decided to add a negative disconnect. Both are within my reach and the negative is readily visable to someone outside the rig.

Sent from my iPhone using Tapatalk

 

[John Galbreath Jr.]

I had one of my disconnects stop working when I got to Harlan. I just put both wires on one side to ride. Today, i went to swap it out and realized it fell apart. I am returning it to the eBay seller for a refund. I am lucky the exposed terminals did not find grounded metal. I went to a higher capacity and higher quality cutoff. Had to do a little changing to make these fit. Now one on both positive and negative.

This is how I found it. Two pieces were a n the belly pan. This is the new Summit ones.

Size comparison.

Sent from my iPad using Tapatalk with my left thumb.

 

[Jep72m]

I had one of my disconnects stop working when I got to Harlan. I just put both wires on one side to ride. Today, i went to swap it out and realized it fell apart. I am returning it to the eBay seller for a refund. I am lucky the exposed terminals did not find grounded metal. I went to a higher capacity and higher quality cutoff. Had to do a little changing to make these fit. Now one on both positive and negative.

This is how I found it. Two pieces were a n the belly pan. This is the new Summit ones.

Size comparison.

I had the same thing happen back in June at Grayrock. The battery disconnect fell apart and I crossed out the 2 post and rode the rest of the weekend.

I bought this one off ebay with the key. Time will tell if it will hold up.

http://www.ebay.com/itm/Keyed-Master-Battery-Disconnect-Switch-2-post-SPST-kill-cut-off-nhra-nascar-d-/300899913264?pt=Motors_Car_Truck_Parts_Accessories&hash=item460f084e30


Sent from my iPad using Tapatalk with my left thumb.