MTFCA Forum

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?

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

Humblej wrote: ↑

Fri Oct 03, 2025 9:22 am

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

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....

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.

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.

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.

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.

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.

Remote shutoff switch and solenoid. Shutoff switch from Lang's. 6v
1948 ford pickup starter relay.

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

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?

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

Thanks. I looked em up. Quite inexpensive.

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]

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

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.

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.

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

If you need anything automotive electrical, try Del City.

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.


[/size]

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.