battery disconnect switch.
- Thread starter 31chevy
- Start date
It really doesn't matter which side is disconnected. I have had at least 3 of the ones with the green knobs fail. They are cast aluminum gold colored and do not give full power after a while. Bob Shewman gadgiteer@aol.com provides a heavy duty disconnect that give full power with no drop and should last forever. These are specified for use on hospital emergency vehicles. G.M.
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I think the negative side disconnect is for negative ground systems.
When you disconnect the battery, it is safer to disconnect the ground side (first). If your wrench would hit something grounded as you loosen the nut, no sparks fly. But if you disconnect the ungrounded side and the wrench hits a ground, you cause a battery short.
With the grounded side disconnected, dropping anything on either the positive or negative terminals (but not both) won't cause a short. It's unlikely but if you want to choose one, this is the choice.
When you disconnect the battery, it is safer to disconnect the ground side (first). If your wrench would hit something grounded as you loosen the nut, no sparks fly. But if you disconnect the ungrounded side and the wrench hits a ground, you cause a battery short.
With the grounded side disconnected, dropping anything on either the positive or negative terminals (but not both) won't cause a short. It's unlikely but if you want to choose one, this is the choice.
JM 35 Sedan
Well-known member
Use one of the good heavy duty snap action switches designed for this application and sold by many automotive parts suppliers. The best recommendation is to break/open the ground side connection.
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37 Coupe
Well-known member
GM , have you posted wrong email on Bob again? it bounced back on me,think this is one of those "Deja Vu all over again" moments
we always put the switch on the chasis ground ,without a ground one can even accidentally short to the non ground and not have a problem when the circuit is interrupted at the chasis side, flaming river makes a good heavy disconnect , we used them for years on trucks and heavy off road equipment also they have an optional lock out bracket.
fordestes,
fordestes,
V8 Bob
Well-known member
First, avoid the crappy green knob post-style switches. The best are HD inline rotory remotes made by Cole Hersee, Moroso, etc, and those with alternator connections are designed for positive + battery switching (For negative - ground systems). NHRA also requires positive + switching, and that's how all my battery switches are wired. Do some research and you'll find most recommend switching the positive + side. IMO.
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4dFord/SC
Well-known member
JerseyJim
Member
I don't like the looks of the green knob type switches that attach to the battery terminal. As others have mentioned, my experience with them is that they burn or pit as well. I prefer rotary type, bulkhead mounting switches that I can hide. You get what you pay for on these as well. The cheapies tend to fail pretty quickly.
I was in a hurry to get a switch installed and went to my local NAPA store. The only one that they had in stock was an expensive one. Bought it because I wanted to get the job done that day. You could feel the difference. The switch was much more positive than the cheaper versions. That switch has been working flawlessly for three years now and engages just as well as it did when I installed it. The model number was SW29. It will give you sticker shock however.
I was in a hurry to get a switch installed and went to my local NAPA store. The only one that they had in stock was an expensive one. Bought it because I wanted to get the job done that day. You could feel the difference. The switch was much more positive than the cheaper versions. That switch has been working flawlessly for three years now and engages just as well as it did when I installed it. The model number was SW29. It will give you sticker shock however.
I know a lot of you are going to think or say "$84.99, holy crap thet's too much. $84.99 might seem like a lot, but it could save your vehicle, and it's probably less than you spent for the last little "widget" that you bought to finish it. And that "widget probably had nothing to do with safety or operation of the car. Now, if it's at night that something happens and your car is in the garage/shop -------------, and your garage shop could be attached to your house----------------- and your family could be sleeping in the house-------------------
Pretty cheap insurance if you ask me.
Pretty cheap insurance if you ask me.
Hamtown Al
Well-known member
I don't know what is really best but I have been putting my disconnect switch in the positive line with the switch normally on the floor of the vehicle slightly under the front edge of the passenger side seat since the early 70s. A HANDY inside switch can do wonders for your piece of mind when you car starts smoking while driving down the road and the alternator suddenly cooks! I switched it off, the wife stopped getting excited, and we coasted to a driveway and got off the road.
Put the sw where you can get to it NOW! if necessary.
JMO.... and the wife's!
Hamtown
Put the sw where you can get to it NOW! if necessary.
JMO.... and the wife's!
Hamtown
Randy in ca
Well-known member
So it seems the majority favor putting them on the Negative side, which seems to make sense to me but is the opposite of what the NHRA requirements are (it seems like they should know). Any more insight??
PeteVS
Well-known member
I think (pretty sure) that the NHRA position is that if you try to kill the engine in an emergency by disconnecting the battery, the output from the alternator or generator will continue. The engine will keep itself running as long as the ignition switch is on. I use a switch on the ground side just to make sure that the car is dead when it's parked/stored and I only disconnect it when the engine is already off.
JM 35 Sedan
Well-known member
You may have misunderstood what you read in some of these posts. Negative (-) does not necessarily = ground. My cars are stock 6V positive (+) ground and I put the cutoff switch in the ground or positive (+) side. Now if my cars were connected negative (-) ground I would still put the cutoff switch in the ground side which in this case would be negative (-) ground. Remember that ground does not always = negative (-).
