Electrical Troubleshooting

[67BAJA]

I am having issues figuring out what is going on with my electrical. Thought somebody can shed some light.

I just installed a electrical switch, similiar to the large black/red one for dual batteries (this one is for single batt.) from Mckenzies. I was having draining issues when the car sat in the garage for more than a week. After I set it up, I turned on my GPS with the switch on the OFF position, and it still read 12 volts. I can still run all electrical components, when this switch is on or off. I thought this switch (assuming I hooked it up right) was supposed to kill all power to the car.

The guy at Mckenzies could be wrong, he has been before.

[movindirt]

What type of switch are you using and where in the circuit is it located? You can check the function of the switch with an ohm meter.

[67BAJA]

For some reason I can't attach a file, I have a picture I will try and load later. It is a switch similiar to the one here:

http://www.race-dezert.com/skunkz/mm/60.jpg

Except it is for a single battery. Right now I have it hooked up between the chassis and the NEG side of the battery. I was told to hook it up on the NEG side, but then I also heard the POS side.

I checked the switch, and I know it is turning on and off. On and off still supply power to all electrical components independent on where the switch is set.

[ChuckH]

Almost sounds like something is wired wrong, you need to get some test equipment, get one of these and/or a OHM meter, without these you have no way of telling if you have a bad switch ( doubtful ) or have something wired wrong.

Cheap tester like this can be found at any parts store.
http://www.cardomain.com/item/SOU21000

[67BAJA]

I have a multimeter.

Checking with the ohm setup, at the NEG terminal, and chassis ground (switch in-between), there is 0.3 ohm resistance when switch is on, and 6 ohm resistance when switch is off.

I would think there should be close to zero (which 0.3 is) when the switch is on and infinite or at least a crap load of resistance when the switch is off. Right???

Any other ideas?

[67BAJA]

Can anyoe confirm that this switch can be installed on the NEG side, or on the POS side?

[WannaB-class5]

You went to bling Erik...I just have a quick disconnect on my POS side of the optima. My only question is can you start the bug with the switch in the off pos? Or is it just the electrical components?

[Ryan_P]

Are you running a fuse block or a main power wire to a tray of circuit breakers? If so, place the switch between the the positive battery terminal and the fuse block or tray of circuit breakers. That will cut off all main power to everything in case of an electrical fire takes place.

-Ryan

[14802]

If you are ONLY switching the negative side of your battery, your Positive side will still allow power, if the device you are powering is grounded to the chassis. I'm assuming you are using a "Perko" stlye switch. Make sure the battery ground wire's(ALL THAT ATTACH TO THE NEG. POST AT THE BATTERY) go to the "Perko" switch first.Then all grounding will run thru the switch..

[67BAJA]

If you are ONLY switching the negative side of your battery, your Positive side will still allow power, if the device you are powering is grounded to the chassis. I'm assuming you are using a "Perko" stlye switch. Make sure the battery ground wire's(ALL THAT ATTACH TO THE NEG. POST AT THE BATTERY) go to the "Perko" switch first.Then all grounding will run thru the switch..

I have it setup that the switch comes first off the chassis, and then all other NEG wires and the NEG terminal attach (no bypass around switch).

[14802]

I have it setup that the switch comes first off the chassis, and then all other NEG wires and the NEG terminal attach (no bypass around switch).
Well to get power to your G.P.S. unit or other accessories, it is being grounded by another route.If you have a Positive lug or main(+) point of attachment with multiple accessories are linked to, It might be "bleeding" enough power from one accessory to power another one that is under the same lug? Maybe" bleeding" is not the word, but It is finding ground somehow.
It might be easier to break the Positive side, but if you put it in the negitive side(prefered way) you will never worry about a loose battery shorting on the chassis.

[movindirt]

If you are checking the switch with an ohm meter, you are doing so without power correct? You can't have the battery hooked up when measuring resistance. If you have a DMM I would just use it in DCV mode and and measure between the pos post on the battery to the output side of the switch. Do this with the battery hooked up. If you get 12v when the switch is in the off position then either you still have a ground path around the switch somewhere or the switch is bad. If it seems to be the switch use your meter in the continuity mode to check the switch.

[67BAJA]

Well to get power to your G.P.S. unit or other accessories, it is being grounded by another route.If you have a Positive lug or main(+) point of attachment with multiple accessories are linked to, It might be "bleeding" enough power from one accessory to power another one that is under the same lug? Maybe" bleeding" is not the word, but It is finding ground somehow.
It might be easier to break the Positive side, but if you put it in the negitive side(prefered way) you will never worry about a loose battery shorting on the chassis.

I was thinking that maybe something is grounded somewhere it shouldn't be. You would suggest that if everything was legit, that I would be able to hook it up on the NEG as I do now?

[ntsqd]

If you are ONLY switching the negative side of your battery, your Positive side will still allow power, if the device you are powering is grounded to the chassis.

It takes a complete circut for power to go anywhere. With the switch btwn the chassis and the negative battery terminal: No ground = no power. Putting the switch in the negative side is a perfectly valid thing to do. It is more common to put it in the positive side, but assuming the wiring is correct it makes no difference in performance. Having it in the neg side can have some benefits. Things like EFI computers, alarms, and stereo memory need power while the battery is off. It is sometimes easier to wire their negatives around the switch than their positives.

THE thing you have to keep in mind while doing this is that if you attempt to start the engine with the switch off the only ground available to that ~400 starting amps is thru your stereo./alarm/etc. You want to protect those devices wired past the switch on both sides, ground and power.

Confirm that you have wired the switch with the ground cable from the negative battery post going to one of the switch's terminals. Then from the other terminal there is a cable to the chassis. AND that there are NO wires or cables attached to either end of the cable btwn the battery and the switch. And that battery cable terminal terminal on the switch is not in contact with the chassis.

Somewhere you have a ground to the battery that is only a 6 ohm resistance. You are right, if the switch is off then resistance across the switch terminals should be near infiinite. My bet is some accessory is causing your trouble.

[67BAJA]

NTSQD,

It is in a race car, and I do not want the radio, GPS or anything to operate when battery switch is off.

I confirmed the wiring set up, the NEG terminal has nothing between it and the switch, or the switch and the chassis

[shifty217]

6 ohms is still connected right to ground.
an open circuit should be "OL" or high meg ohms.

Does the battery have any other ground connection to anywhere?
Everything should go through that switch before it can get battery ground.
If that battery has no ground,nothing can work. So it must be grounded some how?
If that swirch reads 6 ohms witht the switch off then it's fubar.
Good luck!
Doug R

[gunny]

is it possible that you used the terminals on the back of your switch to mount the thing
go easy here cause I have seen it done
the body of the switch is isolated from the terminals and is what you should have mounted to your car
I saw a guy do this thinking that since the terminals are so big he could use em to mount the thing drilled three holes in the body of the car then put the battery cables on them then the nuts
this way no matter what he was grounded

[partybarge_pilot]

Take the switch out and test it all by itself. I have seen defective switchs.

[Billnis]

I think the best solution is to wire the disconnect to the Positive terminal of the battery not the Negative side. By doing it to the negative terminal you still have hot circuits just waiting for a ground connection. You could short a postive lead to ground while you are working on the vehicle. Some items in your vehicle could be grounding without a wire. My remote starter solenoid grounds right to the frame. If you were ever in an accident and wanted to remove all power, removing the ground connection might not do it. You might have a body or chassis part crunched up against a positive lead and creating a short. When connecting leads to a battery I was always taught that the positive lead is the first off and the last on.

[movindirt]

I think the best solution is to wire the disconnect to the Positive terminal of the battery not the Negative side. By doing it to the negative terminal you still have hot circuits just waiting for a ground connection. You could short a postive lead to ground while you are working on the vehicle. Some items in your vehicle could be grounding without a wire. My remote starter solenoid grounds right to the frame. If you were ever in an accident and wanted to remove all power, removing the ground connection might not do it. You might have a body or chassis part crunched up against a positive lead and creating a short. When connecting leads to a battery I was always taught that the positive lead is the first off and the last on.

As ntsqd pointed out it doesn't make a difference which side of a circuit you break. Yes if anything conductive bridges the gap of the switch when in the off position the circuit will become hot. This is true weither you put the switch on the positive or negative side. I really think you still have a ground path around the switch but it could be a bed switch.

[67BAJA]

Found the error. The radio ground was wired into the ground wire in between the switch and the battery NEG terminal. This resulted in all the ground traveling through this wire. Thanks for the help guys, I probably would have never seen that, and rewired everything.

:) :)