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About a month or so ago there was a you-tube video posted about witch terminal to use for a battery disconnect.
I have used the negative terminal for close to 15 years on the Negative side of the battery.
I saved the you-tube link but cannot find it.
Friend of a friend needs one on his Semi truck.
Anybody have the link to the video ?
Either will work to disconnect power from the car. I choose to use the positive terminal...just so there is NOTHING in the vehicle with positive power on it when I am working on the car.
Switching the "grounded" terminal as that's the only way to completely isolate the battery and eliminate any chance of an accidental short by something touching the "hot" terminal and/or disconnect switch exposed metal..
The battery mount switches are designed to go on the smaller ground post.
I have quick disconnect switches connected to the negative side....similar to the setup in the video that Richard454 posted. The disconnect switches I am using currently have the small bypass wire and fuse to provide a small amount of volts to the clock which is my primary reason for using the negative terminal quick disconnect.
I get why 7T1vette and KenSny would choose the positive terminal instead for their quick disconnect setup.
Thank you Richard454 that's the one i was looking for.
This guys neighbors Semis truck windshield had a leak on the passenger side where the battery's are, the owner looked out in the driveway at the truck and the cab was filled up with smoke. Had to use bolt cutters to disconnect the cables as they where all red hot.
So, 5k later he is back on the road but is now paranoid about battery and would like to add a disconnect.
Thanks again.
Yeah! Youtube videos are just RIFE with mis-information. Referencing the video by some Serbian guy pounding the bearings out of a Chevy alternator to 'clock-it'.
ANYBODY can vomit onto the internet!
Does this aforementioned video have anything to do with Negative ground C-3 Corvettes that ground the entire electrical system thru the chassis, because it s a fiberglass body??????
Negative post. 45 years with a 'green switch'.
To put a very fine point on this...your battery disconnect is a PRIMARY safety device....it can turn an disaster into a minor annoyance. I find the neg post is more accessible QUICKLY in the event the blue smoke escapes the wires!
To put a very fine point on this...your battery disconnect is a PRIMARY safety device....it can turn an disaster into a minor annoyance. I find the neg post is more accessible QUICKLY in the event the blue smoke escapes the wires!
Unkahal.
I've been in the positive post camp since installing disconnects. Is there an inherent reason the positive post is not recommended? Is it merely access as you mentioned above? THX!
I've been in the positive post camp since installing disconnects. Is there an inherent reason the positive post is not recommended? Is it merely access as you mentioned above? THX!
The post terminals on a battery are different sizes- the negative post is smaller than the positive.
Measure the the disconnect switch and you'll find it was designed to fit the negative terminal. Most have green or black *****.
Side post type will work on either - but it is still recommended to use the ground as your disconnect side.
The big piece of metal behind the seats and across -next to the battery- is grounded to the chassis.
Even though the body is fiberglass (an insulator) the birdcage is still connected/grounded to the chassis.
The disconnect switch has a lot more exposed metal area- if in an accident the battery can easily hit the metal with all the exposed area of the switch.
It's just a better idea-as it has always been taught to remove the ground cable first and connecting it last when replacing the battery.
On a side note- NHRA still requires a positive 'kill' switch- but IIRC all other racing (NASCAR) want the negative kill....
The disconnect switch has a lot more exposed metal area- if in an accident the battery can easily hit the metal with all the exposed area of the switch.
I have quick disconnect switches connected to the negative side....similar to the setup in the video that Richard454 posted. The disconnect switches I am using currently have the small bypass wire and fuse to provide a small amount of volts to the clock which is my primary reason for using the negative terminal quick disconnect.
I get why 7T1vette and KenSny would choose the positive terminal instead for their quick disconnect setup.
FWIW,
NCRS 1968-1969 Technical Information Manual and Judging Guide, 5th Edition P. 47, "Fig. I 13.0 R59S battery with a cut-off switch attached to the negative cable" shows a photo similar to this of the disconnect...
Just to put a further perterberance in the force....
I have used 'Green Switches' for years. As shown above.
The DEFECT in the green switch is that the weight and or the angle/pressure by the stiffness of the wire can OVERRIDE the disconnect. Causing the green switch to 'make' even though it's unscrewed.
I check this by looking at the dome light..... making sure that OFF is OFF!
I have used the bladed style on the positive side for 10 yrs now no problems. I can see the concern of a possible direct short to ground.
I had to relieve some of the brass on the cut off to fit the pos. side terminal post.
Marshal
Switching the "grounded" terminal as that's the only way to completely isolate the battery and eliminate any chance of an accidental short by something touching the "hot" terminal and/or disconnect switch exposed metal..
The battery mount switches are designed to go on the smaller ground post.
Thank you Richard454 that's the one i was looking for.
This guys neighbors Semis truck windshield had a leak on the passenger side where the battery's are, the owner looked out in the driveway at the truck and the cab was filled up with smoke. Had to use bolt cutters to disconnect the cables as they where all red hot.
So, 5k later he is back on the road but is now paranoid about battery and would like to add a disconnect.
Thanks again.
You remove the ground cable from a battery 'first' because most vehicles have metal bodies, etc, etc. and removing the positive terminal might risk some contact between the tools you are using to remove the positive cable and the metal body (which is grounded).....NOT because there is some inherently beneficial reason to remove the negative over the positive cable.
Bottom line: Any owner can choose whichever terminal to install a disconnect switch. Either one will create a complete 'break' in the power circuit within the car. There are some minor risks which can be avoided by choosing one terminal over the other...depending on the type of vehicle and how it is wired.
Last edited by 7T1vette; Feb 18, 2021 at 12:31 AM.
I have used the bladed style on the positive side for 10 yrs now no problems. I can see the concern of a possible direct short to ground. I had to relieve some of the brass on the cut off to fit the pos. side terminal post.
Marshal
EXACTLY- as it was designed for the negative terminal... and you will not get a good connection with the cable on the switch unless you use a negative cable (terminal) on the positive side..
Originally Posted by 7T1vette
Bottom line: Any owner can choose whichever terminal to install a disconnect switch. Either one will create a complete 'break' in the power circuit within the car. There are some minor risks which can be avoided by choosing one terminal over the other...depending on the type of vehicle and how it is wired.
It's not a minor risk when there are the possibility of sparks around a battery.
Battery disconnect terminals
I think I'd fix the leak first.
