Do I Need A Battery Cut-Off?

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CatGuy
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Do I Need A Battery Cut-Off?

Post by CatGuy » Fri Oct 03, 2025 9:10 am

Do I need a battery shut-off on my car? When I got my '28 A 4 years ago it came with one. The car was restored around 10 years ago and the wiring is good. One day I did leave the switch 'on' and it ran the battery down. My fault. There is a draw somewhere that needs fixing, then. Out of all the many old cars I've owned, this is the only one that has a shut-off. I've never considered it before. My '55 Chevy truck has the original wiring in it and no shut off. On my car I just unhook one of the cables when I'm not using it. So, does everyone here use a shut-off? When the cars were new they didn't have one, so what changed?

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Humblej
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Re: Do I Need A Battery Cut-Off?

Post by Humblej » Fri Oct 03, 2025 9:22 am

I have a 1/2" wrench that I use as a battery cut off.


love2T's
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Re: Do I Need A Battery Cut-Off?

Post by love2T's » Fri Oct 03, 2025 9:32 am

Humblej wrote:
Fri Oct 03, 2025 9:22 am
I have a 1/2" wrench that I use as a battery cut off.
:lol: ME TOO! Takes all of one minute and I keep the wrench right there in the back seat floor of my fordor for it.
the other car really don't need it....


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CatGuy
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Re: Do I Need A Battery Cut-Off?

Post by CatGuy » Fri Oct 03, 2025 9:38 am

Humblej wrote:
Fri Oct 03, 2025 9:22 am
I have a 1/2" wrench that I use as a battery cut off.
That's what I have, too! What I forgot to mention is that I don't enjoy leaning into the trunk of my Roadster to do that.


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Re: Do I Need A Battery Cut-Off?

Post by AndyClary » Fri Oct 03, 2025 9:43 am

I have a battery cutoff for all the usual reasons. One happy by product is the ability to let kids sit in the car knowing they can step on the starter button and nothing happens. Kids get in the car almost every time we’re out.


Andy.


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Re: Do I Need A Battery Cut-Off?

Post by mtntee20 » Fri Oct 03, 2025 10:41 am

I have battery cut offs on both our TT and Delivery.

1. Protects the battery from any random power drain.
2, Protects from poor insulation causing a fire when no one is around.
3. Very few people think of this one. Theft prevention. While it is well known, in this community, a thief must know how to drive a T before he steals one, a hidden battery cut out will make a theft "take too long" and thus be a deterrent.

You can go cheap: Harbor Freight ( which I am using with pleasure) all the way to the best: Caterpillar, bullet proof, dust proof, water proof, fuel proof, and will cost more than your T, or it will feel like it.

A cut off with a removable "key" is a blessing and curse. Blessing: NO ONE can turn it on without the key. Curse: NO ONE can turn it on without the key......INCLUDING YOU. If you choose the "key" type, keep a spare key handy, just in case. Most "keys" lock in when ON, but may fall out when OFF.


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Re: Do I Need A Battery Cut-Off?

Post by TXGOAT2 » Fri Oct 03, 2025 12:53 pm

It's a good idea for the several reasons listed above. Putting a fuse in the battery feed wire is also a good idea, with or without a switch.


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Re: Do I Need A Battery Cut-Off?

Post by TXGOAT2 » Fri Oct 03, 2025 12:55 pm

It is possible for a person to inadvertently start a T by stepping on the starter button. If the car is in "high", it could move away under its own power.


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Re: Do I Need A Battery Cut-Off?

Post by Professor Fate » Fri Oct 03, 2025 1:10 pm

Remote shutoff switch and solenoid. Shutoff switch from Lang's. 6v
1948 ford pickup starter relay.
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Re: Do I Need A Battery Cut-Off?

Post by Original Smith » Fri Oct 03, 2025 1:29 pm

Do what you wish. I've never had a battery cut off, and don't need one either!


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Re: Do I Need A Battery Cut-Off?

Post by speedytinc » Fri Oct 03, 2025 1:36 pm

Are currently available battery cutoff switches really good enough to carry the high amp loads of a 6V system?
What size are the terminal studs? 3/8"?
A fellow member has burned out/melted a few. Are there cheap/lite weight units to avoid?
Are there preferred styles? Is the Langs unit adequate & reliable?


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Re: Do I Need A Battery Cut-Off?

Post by mtntee20 » Fri Oct 03, 2025 3:36 pm

John, I can vouch for the Harbor Freight switches. I've used mine on 6volt systems for a couple of years now and have had NO problems with either one.

I am unable to find an amperage spec. on the Harbor Freight unit, but similar units are rated at 300 amps.

NOTE TO ALL: DO NOT BUY OR USE THE BATTERY POST TYPE SWITCHES. I have extensive experience with both types. They both break or corrode and become useless quickly. NOT WORTH THE MONEY.

Good Luck
Last edited by mtntee20 on Fri Oct 03, 2025 3:49 pm, edited 1 time in total.


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Re: Do I Need A Battery Cut-Off?

Post by speedytinc » Fri Oct 03, 2025 3:40 pm

Thanks. I looked em up. Quite inexpensive.


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Re: Do I Need A Battery Cut-Off?

Post by Professor Fate » Fri Oct 03, 2025 3:46 pm

chrome_screenshot_1759520475673.png
I've had this switch in my car for 3 years. Hearty and reliable. Hasn't let me down.Just get crafty as to where you want to hide it.[/size]
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Re: Do I Need A Battery Cut-Off?

Post by Jim Eubanks » Fri Oct 03, 2025 4:29 pm

I have the above switch on all my cars for safety an insurance from easy theft.

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Re: Do I Need A Battery Cut-Off?

Post by JBog » Fri Oct 03, 2025 4:33 pm

I have a fuse at the terminal block that I use as a battery cutoff in addition to general safety. I might add I’ve popped that fuse several times so I am glad I have it.

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Re: Do I Need A Battery Cut-Off?

Post by Charlie B in N.J. » Fri Oct 03, 2025 5:28 pm

You want cheap? Find the problem and fix it. Starter car? Very likely it’s the gen. Cutoff relay. There’s like 7 circuits in the T. Not hard to isolate the problem and keep the $ in that piece of dead cow in your back pocket.
Forget everything you thought you knew.

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Re: Do I Need A Battery Cut-Off?

Post by ewdysar » Fri Oct 03, 2025 5:39 pm

mtntee20 wrote:
Fri Oct 03, 2025 3:36 pm
John, I can vouch for the Harbor Freight switches. I've used mine on 6volt systems for a couple of years now and have had NO problems with either one.

I am unable to find an amperage spec. on the Harbor Freight unit, but similar units are rated at 300 amps.

NOTE TO ALL: DO NOT BUY OR USE THE BATTERY POST TYPE SWITCHES. I have extensive experience with both types. They both break or corrode and become useless quickly. NOT WORTH THE MONEY.

Good Luck
My '27 Runabout came with a battery post cutoff switch, that was probably installed in the '90s. I've had the car 5 years and the switch is still perfectly functional and is not broken or corroded. Getting to the knob through the battery access panel at the front of the trunk is fairly inconvenient, but there is nothing inherently bad in the design or construction of the switch itself. Your milage may vary. ;)

Keep crankin',
Eric


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Re: Do I Need A Battery Cut-Off?

Post by big2bird » Fri Oct 03, 2025 6:30 pm

If you need anything automotive electrical, try Del City.


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Re: Do I Need A Battery Cut-Off?

Post by Professor Fate » Fri Oct 03, 2025 6:43 pm

4NGU3_AS02.jpeg
use this and hope it doesn't back off or vibrate loose while engine is running.... no ground makes your generator produce "The magic smoke...." use the one i posted from LANG'S and put it within reach of the driver, so you can shut power down quickly and safely without having to pull over, get out, and access the battery....
Use this one!
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Re: Do I Need A Battery Cut-Off?

Post by Steve Jelf » Fri Oct 03, 2025 6:50 pm

Obviously, some like it and some don't. I'll leave it to the rest of you to sort out the pros and cons. If you decide in favor, here's some guidance.


March 1922 to 1927  Wiring Diagram.jpg
[/size]
The inevitable often happens.
1915 Runabout
1923 Touring


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Re: Do I Need A Battery Cut-Off?

Post by Professor Fate » Fri Oct 03, 2025 6:57 pm

This depicts what I use. But I use the switch to cut all power to the battery. The battery remains grounded whether switch on or off.
Starter-Solenoid-Wiring-Diagram.jpg
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