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Battery disconnect switch

orange69

Full Member
Joined
Feb 10, 2002
Messages
309
Does it matter which side (+ or -) that a battery disconnect switch goes on? Also what gauge of wire should I use? Total distance would be about six feet.

Thanks.
 

Jerseydevil

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Oct 21, 2009
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Loc.
West Chester PA
I don't know if it really mattersfor security purposes, but I think I'd put mine on the positive side, because some accessories have their own ground, so they could still potentially drain your bettery, even if you have the ground side switch open.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
37,067
Doesn't matter which side. You are opening the circuit, doesn't matter where you open it at it is still open.
Just size it to match the existing battery cable, probably 4-gauge.
 
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orange69

orange69

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Feb 10, 2002
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Thanks for replies. Currently I have it connected to the positive side, but was told it should be on the negative side. I didn't think it mattered either but thought I'd ask. Today I was looking at the cables because it wouldn't start and the cables were extremely hot, so I was wondering if I should upgrade to 2 gauge since I need to replace them anyways.

Thanks for advice.
 

Pa PITT

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Jul 15, 2005
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11,300
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Stephenville TEXAS
.. I have never been good at the electric of our rides. I've always put them on the + sides but the last few years I've been told it's better to put them on the - side. They said it was better to keep it hot to the items . I still don't understand why.
 

66broncoCT

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Feb 6, 2012
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Torrington, CT
I don't know if it really mattersfor security purposes, but I think I'd put mine on the positive side, because some accessories have their own ground, so they could still potentially drain your bettery, even if you have the ground side switch open.

Yes, but if your disconnecting the ground at the battery youre killing the power so it cant drain your battery. The accessories independent grounds are grounded to either the body or frame, which is then grounded to the battery. It's just a big loop from the positive side to the accessory to battery ground. So if you take off/disconnect the battery ground youre opening the circuit which means no power used. To the OP, I'm not sure if it matters which side you put it on, I always do the negative side but it's purely preference. And if you have efi you shouldn't disconnect the computers always hot, it screws with the learned idle.
 
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orange69

orange69

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Feb 10, 2002
Messages
309
I've had mine on the neg side for years, no issues.

Hot cables and a no start issues sounds like you have a starter or relay problem.

I've been slowly replacing parts trying to figure this problem out. I put on a new starter and solenoid and it seemed to help alot. It starts fine when cold, its when I try to start it after its warmed up that I'm having issues. Cleaned battery cables, no change. Then I figured I'd check the connections on the disconnect switch and that's when I burnt my fingers. My next step is to replace the battery cables and am thinking of using larger cable.
 

patterdale

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Joined
May 24, 2010
Messages
1,252
Check the cables for white powdery stuff near the battery ends inside the cable. They can corrode inside the casing and seem normal but be down to just a few strands carrying the current. (thus the heat) After you replace them do a post mortem. I would put the disconnect on the negative side of the battery as close to the battery as possible. It is just best to have as few connections on the positive side to make accidental contact with when wrenching and generally fooling around. The other problem you could have is a bad starter. They will run fine when cold but heat them up and the resistence goes up as well. Mine was turning slow when hot so I blew it out (carbon dust from brushes not letting them make full contact with the armature) and put on new cables. It spins like new now. It doesn't hurt to take the end cap off and touch up the armature with some emery cloth and contact cleaner either.
 

Broncobowsher

Total hack
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Jun 4, 2002
Messages
37,067
There's a reason the ignition switch is on the positive lead.

So the engine can be built as cheap as possible. Only 1 wire run to the distributor. The ground is cycled via the distributor.

Look at EFI, all the control circuits (injectors, IAC, solenoids, fuel pump relay) are all switched on the ground side.

When you pull the batteries out of your kids toy that won't shut up at 2AM it doesn't matter if you pull the negative or the positive, as soon as you brak any of the connections it goes dead. Open circuit is an open circuit, doesn't matter where it is open at.
 
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orange69

orange69

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Feb 10, 2002
Messages
309
Check the cables for white powdery stuff near the battery ends inside the cable. They can corrode inside the casing and seem normal but be down to just a few strands carrying the current. (thus the heat) After you replace them do a post mortem. I would put the disconnect on the negative side of the battery as close to the battery as possible. It is just best to have as few connections on the positive side to make accidental contact with when wrenching and generally fooling around. The other problem you could have is a bad starter. They will run fine when cold but heat them up and the resistence goes up as well. Mine was turning slow when hot so I blew it out (carbon dust from brushes not letting them make full contact with the armature) and put on new cables. It spins like new now. It doesn't hurt to take the end cap off and touch up the armature with some emery cloth and contact cleaner either.

Thanks for the tip on the starter. I will try that if these cables don't fix the problem. I'm pretty confident it will. Sounds like its a matter of preference on which side to place the disconnect switch. Now that I thought about it, every manual I've read say to disconnect the negative before doing any work, so maybe I will move it to the negative side.
 
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orange69

orange69

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Feb 10, 2002
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So I put on new cables and it starts great now, even after it's warmed up. ;D I also put the disconnect switch on the negative side. But now another problem surfaced. I have a dual post battery. My winch is hooked up to the side terminals. So now it's grounding through the winch! It will barely turn over when the switch is disconnected, and the headlights will turn on. So I disconnected the - side of the winch and everything seems like it should; no start, no headlights, etc. So is there something not wired up correctly on my winch? Do I somehow isolate how the winch is mounted? I've checked to see if a winch cable is shorted out against the frame somewhere and couldn't find anything. Anymore help would be greatly appreciated!

Thanks
 

Broncobowsher

Total hack
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Jun 4, 2002
Messages
37,067
Move the ground for the winch off the side post and put it on the disconnect switch (non-battery side).

You have multiple ground paths, you only disconnected one of them.
If you follow the ground cable into the winch, it probably goes to the winch motors body. A dedicated ground since the chassis ground is very poor (all insulated with rubber, motor mounts, trans mount, body mounts, etc). You now have a weak ground from the chassis back to the engine, but good enough for the lights to work.
 
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orange69

orange69

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Feb 10, 2002
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309
Thanks Broncobowsher. I thought of that too, but I mounted the switch in the cab, so its easy to get to. I would have to get a longer cable for the winch and my lack of funds right now means it won't happen anytime soon. Next payday next month maybe. That's why I was wondering if there was a way to isolate the winch mount somehow. For now I might just leave the winch disconnected or put another disconnect switch on the side terminal. What if I moved the winch ground to where the battery ground bolts to the engine block? Would winching pull too many amps through the switch?
 

Broncobowsher

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Jun 4, 2002
Messages
37,067
But you would have to run the positive feed to the switch as well, so no gain.
Benifit of running the ground is if anything happens (wire chafe) ground shorting to ground does nothing. Power shorts to ground makes a mess.
 

asinor

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May 13, 2011
Messages
1,396
Loc.
Tulsa, OK
Always disconnect the ground/common side first. Its safer and most of the other electronics, gauges, etc in your car are controlled by connecting, disconnecting or varying the ground resistance. If you drop a wrench on the positive terminal and it touches anything metal while the ground is connected it is a dead short, if the ground is disconnected it will not short.
 

jim3326

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Joined
Jul 12, 2010
Messages
1,781
Loc.
Appleturkey
I had a continuous duty solenoid that I hooked up to the negative side, that way I only had to run a 14 ga. wire to a switch in the cab. I would put a quick disconnect plug on the winch and only plug it in when you needed it.

Jim W.
 
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