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installing a battery cut off switch.


bluefoxamazone

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It makes no difference.  The battery disconnect switch prevents current flow.  It presents an open circuit to the battery, so if there is no path for current flow, your battery is isolated from the car's circuitry.  It would be the same result if you simply disconnected either one of the battery cables.

 

Wayne

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Disconnect the ground side?  Well, if you cut off the hot side, you could still have some metal thing fall on the (+) post and touch metal elsewhere, and get an arc.  If you disconnect the ground side, you would have to drop something across both posts to get the accidental arc.

 

I use disconnecting cable clamps at both posts, of the main battery and of the auxiliary battery.  It makes it easy to disconnect the batteries and to switch them if need should be.  (But come to think of it, I recently disconnected the hot side of each battery.  Oh, I guess it doesn't matter!)

 

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You should always go with the ground. Just like wiring a light switch in a wall. You don't run the hot wire to the switch. That way there is less chance of getting nailed when you flip the switch if you are providing a ground with yourself.

 

I've heard of battery disconnect switches but I guess something is getting by me. Why put one? The ignition switch is suppose to be the battery switch isn't it? Perhaps a short causing battery drain - but that's something that should be tracked down. Why else put a battery disconnect switch?

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Lloyd, on 31 Dec 2014 - 8:58 PM, said:

Just like wiring a light switch in a wall. You don't run the hot wire to the switch.

When wiring a light switch I always switch the hot wire and not the neutral or ground. I don't want the light socket hot all the time espically when I replace bulbs.

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When wiring a light switch I always switch the hot wire and not the neutral or ground. I don't want the light socket hot all the time espically when I replace bulbs.

Don is correct.  The hot wire is the conductor to be switched, never the neutral.  Sorry for getting OT.

 

Wayne

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Mr. C is right on, with house wiring.  You want the shell of a light socket to be continuously connected to the neutral wire, and the hot wire switched to the center contact of the socket.  When you are screwing the bulb in, the threaded part is exposed and in contact with the neutrally-wired shell.  You don't want the shell hot.  

 

Similarly with tools and appliances.  The neutral blade of the plug is wider than the hot blade, so that the wiring does not get reversed. Some double-insulated tools, and low-voltage chargers, don't care how they are plugged in, and the blades are both narrow. 

 

Back on topic:  Why have a shut-off for your vintage car? Over time, you could be getting something causing battery drain, or there may be some anomaly in the ancient wiring that could overheat.  With a shut-off, this can't happen, and no one can hot-wire the car.  Sleep better.  

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When wiring a light switch I always switch the hot wire and not the neutral or ground. I don't want the light socket hot all the time espically when I replace bulbs.

 Yep your right Don. My mistake, I got it backwards. Seems I do recall an old electrician telling me that you don't want to take the chance of getting shocked changing the bulb and not flipping the switch. Hot wire it is. Thank you.

 

I can see using a switch for preventing hot wiring your car, but battery drain should be tracked down and fixed. When I have had drain problems I've disconnected the battery at nights as a temp remedy but only temp.

But in my Plymouth P8 the battery is in a box below the car so it would be easier to disconnect with a switch if I needed to rather than accessing the battery to pull a terminal.

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Rather than a battery disconnect switch,I use SAE 1/2" wrench to disconnect the ground cable clamp at the battery  - (positive in my Dodge).

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O/k so mines a 12 volt hotrod(1940 Dodge) with the battery mounted in the trunk but the battery isolator switch is mounted on the side of the console, beside my left leg(RHD remember) so I just lean down, turn the switch and theres no power to anything........makes a very good electrical safety item and also anti theft tool.......andyd

Edited by Andydodge
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Meant to include this pic......you can see the battery cutoff/isolator switch in the pic, its the small black item sticking out of the side of the console......the positive cable runs from the trunk mounted battery along the floor up into the console and to the switch terminal........andyd

post-612-0-26752900-1420086080_thumb.jpg

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And heres a pic of the trunk showing the battery box and the power lead heading up front to the cutoff switch........andyd

post-612-0-25642200-1420144621_thumb.jpg

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...Not pretty - but here's a photo of my low tech,low cost,6 volt,short run battery disconnect. ;)

post-296-0-54736300-1420147245_thumb.jpg

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I've heard of battery disconnect switches but I guess something is getting by me. Why put one? The ignition switch is suppose to be the battery switch isn't it? Perhaps a short causing battery drain - but that's something that should be tracked down. Why else put a battery disconnect switch?

 

 

They are really handy if you have an issue like a stuck starter, or horn contacts stuck together. It can also save your car burning up if there is a short that starts smoking...it takes a long time to disconnect a battery cable.

 

Rob

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