Battery Disconnect / Isolator
 

I currently have the six volt positive ground system in my car. My question is, which terminal do I put my battery isolator / disconnect on, positive or negative?

Thanks in advance!

Re: Battery Disconnect / Isolator
 

make sure you have proper cable size for 6 volts (00 size battery cable,12 volt use #1 size battery cable

Re: Battery Disconnect / Isolator
 

put the disconnect or night switch on the ground cable. positive.
with the switch off that will kill all power from the battery.

the same idea as disconnecting your ground wire first before working on your car.

Re: Battery Disconnect / Isolator
 

Agree!

Re: Battery Disconnect / Isolator
 

"Old Ugly" What a great name!

Re: Battery Disconnect / Isolator
 

The disconnect switch is good for assuring the battery does not discharge while the car sits, or for theft deterrence. But it is most useful when there is an emergency, such as a short causing a fire or the starter switch sticking. So put it somewhere where it is accessible.

Re: Battery Disconnect / Isolator
 

this is so true.
one of the biggest causes for the battery discharging while the car is parked is the generator cut out. a night switch, as long as you shut the switch off, will prevent that.

Re: Battery Disconnect / Isolator
 

haha.
my father-in-law gave me that nickname in the mid 1980s, i don't know why, i wasn't even old then.

Re: Battery Disconnect / Isolator
 

55 years ago , when I first got my A I took her to the car wash to clean the engine preparing for detailing the engine and firewall . Smoke began leaving the firewall wiring, so I flipped the rubber mat back , popped the battery cover off , and wiggled the positive ground battery terminal off ! Well it took me longer to type this than to actually disconnect the battery ! From then on when I reinstall the battery terminal I install it “ a little lose “ so that I can remove it by hand , wiggle and pulling it up and off , Fords original battery disconnect !

Re: Battery Disconnect / Isolator
 

Hello, I have a disconnect switch on the 31 , connecting to the ground cable, the switch itself is mounted to to seat riser for easy access.Pictures don’t show very well, on other cars without the seat riser , it might be able to mount it on the cross rail under the seat .

Re: Battery Disconnect / Isolator
 

Like looking for Waldo, I can't see the switch. Good idea though. Can you buy a wire long enough to reach the battery.

Re: Battery Disconnect / Isolator
 

I have my disconnect switch mount in the floor just in front of the seat in my Town Sedan on the ground wire.

From Bottom:
https://live.staticflickr.com/65535/...23e5cd87ea.jpg

Re: Battery Disconnect / Isolator
 

Y-Blockhead did you just mount it in a hole in the frame or did you have to drill one.
Do yu have a picture of it mounted.

Re: Battery Disconnect / Isolator
 

Tom, I had to punch a hole in the cross brace in front of the seat. I will try to get a better picture later today.

Re: Battery Disconnect / Isolator
 

LOL. I just walked behind my '31 and the brake lights were on. I had removed the rear brakes yesterday, finally disconnecting the last brake rods (fronts were already off). Took me just a second or two to lift the driver's side hood and pull the fuse. It is a blade type, easy in and out.

I normally pull the fuse before any major work. Forgot this time. The brake lights are LEDs, so no big deal. I'll put the batt on charge while I get the drums ready to ship.

Re: Battery Disconnect / Isolator
 

Tom, here is a different angle. That is the brake crossshaft just below it.

https://live.staticflickr.com/65535/...24b7e1caba.jpg

Re: Battery Disconnect / Isolator
 

Hello again, better picture this
time two holes were drill for cables in curtain pan to attach to switch, probably won’t be able to duplicate this setup but the is for a 31 Roadster .

Re: Battery Disconnect / Isolator
 

Tom, I don't know if this helps are not, hard place to get a picture...

https://live.staticflickr.com/65535/...f43d4c26b7.jpg

Re: Battery Disconnect / Isolator
 

Did you ever get the correct answer to your question???!!!

Re: Battery Disconnect / Isolator
 

I believe the OP's question was answered in post #3.

Re: Battery Disconnect / Isolator
 

I use a switch in all of my cars. When I got my very first one, it was fitted with one of those horrible ones that fit on top of the battery - the ones with a green wheel on them. NEVER use one of those. Their life is very short and they can leave you stranded on the side of the road. Don't ask how I know.

Re: Battery Disconnect / Isolator
 

Mine came with the car and is mounted on the side of my seat riser. I love it and I think every Model A should have one.

Re: Battery Disconnect / Isolator
 

Actually the first answer was given in Post #2. Does anybody recognize where Gary copied that page is from?

-
https://www.fordbarn.com/forum/attac...5&d=1779429677

Re: Battery Disconnect / Isolator
 

Actually, no. The first correct answer is in Post #3, on the ground wire. Post #2 shows the switch on the supply wire.

Re: Battery Disconnect / Isolator
 

I don't think he is very old! ;)

Re: Battery Disconnect / Isolator
 

Another thread here with good ideas.

https://www.fordbarn.com/forum/showt...ch#post2068301

Re: Battery Disconnect / Isolator
 

Thank You.

Re: Battery Disconnect / Isolator
 

Ground side or supply side really not much differance. Most of mine are on the suply side because they need to meet the rule book for NHRA drag racing and there very clear on the master switch wiring. I know that were not racing here but 50 years of use with no ill efects I think putting the switch on supply side is fine, everything else in your car is switched on the supply side with no problems :)

Re: Battery Disconnect / Isolator
 

I don't get the picture, maybe there's different quality switches. I keep hearing horror stories about the battery mounted switches. I have one that's been on a vehicle (not a Model A) for 10 years and never a problem w/it. Vehicle gets used about once a month.

Re: Battery Disconnect / Isolator
 

The battery disconnect switches used on boats are the best quality. Probably overkill for a car. The marine switches are available that disconnect both sides of the battery. $$$$

Re: Battery Disconnect / Isolator
 

If you have a 30 amp fuse installed, are you expecting your starter switch to fail. IMHO, that would be the only reason to install a battery cutout.

Re: Battery Disconnect / Isolator
 

See post #6

Re: Battery Disconnect / Isolator
 

What does the fuse have to do with the starter switch? Other than being mounted on it.Any number of things can go wrong and caues a problem while sitting around.Most common ones I have been seen have been sticking cutouts,and sticking brake light switches.I've seen two problems from switches mounted in the hot side.One in an A,mounted on the firewall.The cable worked it's way out of the crimp and bounced around arcing until it wedged itself in a solid spot and blew the battery up.Another was in a Comet drag car,(Maverick) and the switch was mounted where the gas cap used to be at the rear of the car.The trunk was full of camping stuff,with a couple cans of gas and a propane bottle.That fire even melted the rear tires on the trailer it was on but the fuel cell in the trunk never burned.I've never seen a credible reason to put the switch in the hot side,it always seems to be,well they told me to.

Re: Battery Disconnect / Isolator
 

To me, it is common sense to put the switch on the earth (ground) side. That isolates EVERYTHING - no half measures.

Re: Battery Disconnect / Isolator
 

Oh, it is more than a name. He really is old and ugly!:p

Re: Battery Disconnect / Isolator
 

I second the suggestion to locate the cutoff switch near/through the seat riser. The new-to-me Fordor slant had it mounted through the firewall next to the clutch pedal. The seller didn’t mention its existence, and twenty minutes after writing him a check I accidentally shut off the current with my foot while approaching an intersection in Houston. Everything turned out fine, and I had a cutoff switch relocated.

Re: Battery Disconnect / Isolator
 

Attachment 586081

In 1972 I had a wiring harness fire in my first Model A. Thankfully the damage was minimal. I’ve installed a battery disconnect switch in every Model A I’ve owned since that incident. Lesson learned.

Easy access to the switch in an emergency is often overlooked. Cutting the power could be the difference between minimal damage and total loss. When seconds count the fire department is minutes away.

Some models can be challenging to find a location for the switch. There are some really clever solutions out there. The attached photo is my current 1929 Tudor. I can easily reach the switch from the driver’s seat.

Re: Battery Disconnect / Isolator
 

X-2 ! Then you only need to be careful with the battery ! You don’t want to cross the posts with something metal !

Re: Battery Disconnect / Isolator
 

With the switch OFF everything IS isolated except for the short length of cable between the battery and the switch no matter what side the switch is in, OFF breaks the path for currant.
Just like your headlight switch, OFF and no currant between the switch and the light
The switch that's in the currant supply side ;)
Sloppy workmanship, bad or loose conection, and unprotected conections points are just asking for trouble at some point in time no matter how you wire a switch :)

Re: Battery Disconnect / Isolator
 

A couple of months ago in the Restorer or Model A News there was an article about a Model A the burned due to the clutch rod coming in contact with the power cable. If there was a S/O switch on the ground side, a lot of damage could have been prevented. Another fella had the battery hold down come in contact with the negitave terminal. Same situation.

I realize these are not common occurances, but they do happen.

BTW, I thought I would mention, our club does have genuine Ford Model A Smoke available in limited quantities if you inadvertently let yours out... don't use the Lucas smoke that is on the market!

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