Battery Shutoff switch location question

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Jim64

Jim64

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Hi Folks - I have relocated my battery to the trunk, on the passenger side. If I want to go to a track, I need a power cutoff switch. I know how to wire it in, but I've been trying to figure out the best location.

The picture attached is the underside of the area where my battery is. (The hold-down bracket bolts are visible in the picture.) I'm wondering if I'm allowed to place the switch where I'm holding it.

It's hard to tell, but there's probably 3" clearance between the switch and the leaf spring, so interference isn't an issue.

Any reason I can't put it there, or does it need to be "inside"?

One advantage of putting it there is that I could hide it behind one of the bumperettes when I'm not at a track, and would still be able to use it.

Battery_Shutoff.jpg
 
as a former nhra tech official, it has to be located in an area easily accessible to starting line personnel in case the car/truck has to be shut off.
 
I was under the impression it had to be VISIBLE, meaning the bumper, etc. "If I ever" get mine back on the road, I intend to mount it in the trunk, with and outer sleeve/ inner rod "push" setup for theft. Open the trunk to engage the switch, the knob will protrude out the rear, and push it to kill the switch. Pulling it out will not re-engage the switch, rather just slip the tubing on the rod
 
Most tracks go by NHRA rules.
The rule, Section 21 page 37 8:4, part of NHRA's General Regulations, says that a Battery Disconnect is "Mandatory when battery is relocated, or as outlined in Class Requirements. An electrical power cutoff switch (one only) must be installed on the rearmost part of each vehicle and be easily accessible from outside the car body. This cutoff switch must be connected to the positive side of the electrical system and must stop all electrical functions including magneto ignition. The off position must be clearly indicated with the word "OFF." If switch is "push/pull" type, "push" must be the action for shutting off the electrical system, "pull" to turn it on. Any rods or cables used to activate the switch must be minimum 1/8-inch diameter. Plastic or keyed switches prohibited.
 
Jim64 said:
Hi Folks - I have relocated my battery to the trunk, on the passenger side. If I want to go to a track, I need a power cutoff switch. I know how to wire it in, but I've been trying to figure out the best location.

The picture attached is the underside of the area where my battery is. (The hold-down bracket bolts are visible in the picture.) I'm wondering if I'm allowed to place the switch where I'm holding it.

It's hard to tell, but there's probably 3" clearance between the switch and the leaf spring, so interference isn't an issue.

Any reason I can't put it there, or does it need to be "inside"?

One advantage of putting it there is that I could hide it behind one of the bumperettes when I'm not at a track, and would still be able to use it.

View attachment 1716012379
Click to expand...
God forbid there's a car fire. You're not going to want to reach under the fuel tank to throw a switch
 
On my 68 Barracuda, I drilled a hole just below the RH tailamp and passed the rod thru it, then bolted the switch down behind the battery. Remember, your switch has to cut the alternator as well, else the running engine will keep right on running. I used a HD relay in the Field coil.
 
You can mount the actual switch there, just need a rod going to the back per the rules shown above. So, you could use a piece of aluminum angle for the push/pull handle to slide through to avoid penetrating the bumper. It’ll get sprayed with burnout water and rubber in that location though.

I threw a rod not long ago, which slicked the tires and the car ended up in the wall. Safety safari got there as I was getting out and flicked my cutoff as first order of business; they’re well trained. It needs to be conspicuous for EVERYONE’S safety…imagine someone getting hurt trying to save you.
 
i would throw in a little caution here with rod type linkage. i have seen it happen. got a call from a friend that had that on his street/strip car. if you use that type, make a detent in the rods. as the linkage wears, it my become loose to where it my slide like stuff does in the bed when you take off. sure it will probably be some time before it is sloppy. story on friend. he hammered it to get on to highway and his was so loose, it caused the rod to slide to off. he had everything in the car power. door opening solenoids, windows, etc, etc. he could not open the doors, roll windows down. called and said he needed help. when help arrived, all that needed done was flip rod to power.
 
Even if the rules said you could mount the switch where the OP wanted to I wouldn’t do it.

You don’t want someone who doesn’t know the car looking for the kill switch while you are unconscious and your *** is on fire.

Thats a bad scenario and falls under the “just because you can doesn’t mean you should” banner.
 
The "switch" itself can theoretically be installed anywhere but no matter where it's located, it has to be easily actuated outside the car by track personnel in case of emergency. Often the switch is in the trunk which generally can't be seen but as long as there is a way to find and actuate the lever quickly then it's fine.

If you do put it underneath where you show in the pic, you'd need to have a lever attached to it in clear view for access and marked indicating what the lever does (i.e; "push off"). I looked at doing it that way myself but decided against it because I drive my car on the street. With the switch underneath, you'll have to run the wiring through the floor and as everyone understands, street driving will always increase the chances of "something happening". Previously I had the cutoff switch under the rear bumper which is similar, just not as far forward. While easily installed and accessed, running all the wires through the floor was less than ideal.

Here's what I ended up doing. Don't mind the mile-long handle, this pic was just for mock up, it will be trimmed to where it's just and inch or two off the bumper. It can also be easily removed when not at the track. To actuate the switch only takes about an inch and a half of movement. Having the switch bracket a little more forward helps to keep the cables slightly shorter. if I switch to a fuel cell, the lever would have to be reworked to put the jog farther back but the concept would the same.
IMG_3050.jpg


The reason I went though all this was because I didn't want to drill any holes in my tail light lenses or pristine rear panel. There's a small area in the upper right corner of the license plate opening where the lever goes through but to reach the switch obviously required the lever to be configured the way it is. Eventually there will be a "push off" sticker on the bumper.
IMG_3041.jpg


I know my method is not typical. If you don't care about drilling a hole in the rear panel or tail light lens then that's probably the easiset way to do it.
 
I appreciate all the input - maybe I can clarify. I've attached another pic that I've marked up using my awesome editing skills.

I've drawn the switch (it's that black rectangle thing) approximately where it will sit below the floor. The dashed silver line is where the rod will be. Note that it will be directly in line with the bottom section of the bumperette. With the bumperette in place, the rod would not have a handle, and the end of the rod would fit inside the bottom of the bumperette. In that configuration, I could reach under and operate the switch if I wanted to.

At the track, I would simply remove the bumperette, put the handle on the rod, and put the "PUSH OFF" sticker on the bumper above the handle. I would make sure it is CLEARLY visible to track staff.

I plan to put some sort of shield over the switch to protect from water and debris. The only real downside I see is having to run wires through the floor, but it does avoid me having to put a hole in the sheet-metal above the bumper, or through a taillight.

Rear_Corner_Edit.jpg
 
I don’t see why that wouldn’t work.

BTW there are solid state disconnect switches available now that completely do-away with the traditional disconnect switch and utilize an electronic push button to isolate the battery. Just have to find a place to mount the button. They are REALLY expensive though.

Solid state battery disconnect

Looks like Waytek sells the module but you’d have to figure out the rest.

Waytek electronic battery disconnect

I looked into one of these but decided it was too expensive. The first one I linked actually almost doubled in price over the last two years from what I remember.

Finding a spot for the button was also a limiting factor since I didn’t want to drill any holes.
 
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