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well I just bought a battery shut off for my 72 ,and wondering if I should put it on the positive side or the negative side ,does it matter ,everyone have a good weekend!!! Bill
When you connect or disconnect a battery with the ground attached, even a shut-off switch, you take the risk of a spark arc. The ground post makes most sense. Think of it like the first cable off a battery and the last to be put on. And nothing can work with no ground. Neg post on mine.
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I have a rotary kill switch wired in on the positive side. Its on the wall between the seats so I can kill the power easily without getting into the battery compartment. Batteries can spark on either strap. The reason you bolt on the negative last is when you are tightening the positive first and the wrench contacts the positive side and the bare metal in the engine ompartment, you wont weld the wrench to the frame. If the negative is being tightened second and it touches the bare metal, then nothing will happen.
Really not a worry in a fiberglass compartment but you never know, its always wise to take the negative off first and put it on last and dont wear rings while you are working on a battery. The Navy Times had a picture of a finger burned off were the wedding ring had been as a safety advisory. I was googling pictures of burned off fingers but it seemed it would be a little too gruesome for this forum
Last edited by Rescue Rogers; Feb 15, 2019 at 08:45 PM.
My intent is to NOT have power on when working on my car. In a "plastic" car, positive (+) side stays connected to lots of stuff; ground is 'switched' to connect the circuit.
IIRC, seems to me NHRA required all disconnects to be on the positive side, Stock car was on the Negative (and I think they changed to switching the positive a while ago) and this was so that the was no power anywhere in the car when off and also to allow them to cut the power in the event of a crash (again spark) but of course has no effect when the car is running
I believe installing the switch on the negative for us "storage" car guys is to turn off the negative first just like you would when removing the battery, where if you slip with the wrench it doesn't matter hitting any grounded frame/brackets, etc. And this just came across to the quick disconnects and to corvettes regardless of our fiberglass tubs
That said I use a blade on the negative, a small jumper fuse to keep the radio presets and I leave the drives seat tipped ahead as a reminder to turn the switch back on before trying to start it
M
Great video. Everyone who posted here should take a few minutes and watch. These safety tips don't just apply to car batteries. Last summer I had quite a scare. I have a canvas bag that I carry supplies in when I travel to my hunting camp. When I left camp, I had a 6 volt lantern battery from a trail cam that needed a recharge, as it was just about dead. Without much thought, I threw it in the bag in the trunk of my Civic. When I pulled in my driveway, I smelled something burning. I figured the neighbor had a fire going in his fireplace. When I opened my trunk I got a faceful of smoke. Luckily, the canvas bag was only smoldering and hadn't burst into flames, yet. Apparently, a spare set of keys I carried in the bag had come into contact with the spring posts of the battery and shorted it out. Ruined the bag and the battery, but could have been much worse. Really scared the hell out of me.
Duane
battery shut off ???
