Master Cutoff Switch

Keith 944 · 03-23-2019, 04:09 PM

Quote:

Originally Posted by FireSale

Ditto.

This Might be part of the problem, you get in an accident, shut your power off, first guy there thinks he’s turning it off and has turned it back on...
It should also be mandatory if you have one inside the car it moves the lever outside the car also, which I’m sure most people already do

Larry Hill · 03-23-2019, 09:19 PM

The disconnect inside the car will not be affected by the outside disconnect being in the on position. The outside disconnect feeds the inside disconnect.

w

FireSale · 03-23-2019, 10:24 PM

Quote:

Originally Posted by Keith 944

This Might be part of the problem, you get in an accident, shut your power off, first guy there thinks he’s turning it off and has turned it back on...
It should also be mandatory if you have one inside the car it moves the lever outside the car also, which I’m sure most people already do

When I had a push-pull system, I had a cable running from the trunk switch to a lever in the cockpit, Pushing the lever physically moved the rod on the back bumper. Since emergency persons are trained to move that switch, they could possibly turn the car back on. My current setup is a rotary switch on the back deck that cuts all power between the battery and the car. The power feed into the cabin is through a continuous duty Cole Hearse solenoid connected to an aircraft switch on the console to energize it. If something goes haywire I can slap that switch and kill all the accessories and ignition power. There is still one hot wire in the cabin (the battery cable) but the juice isn't going anywhere. It's a quick way of shutting off the ignition and fuel pump without flipping multiple switches.

Jeff Stout · 03-24-2019, 11:27 AM

If I have battery in stock location and add a second battery in back do I need a master cut off switch?
I think I don't but asking as I need to add a battery.

FireSale · 03-24-2019, 12:01 PM

Quote:

Originally Posted by Jeff Stout

If I have battery in stock location and add a second battery in back do I need a master cut off switch?
I think I don't but asking as I need to add a battery.

General: 8.4 Mandatory when battery is relocated or as outlined in Class Requirements.

Check the current class rules for your car. My guess is yes. Battery in trunk = rear deck mount cut off.

Jeff Stout · 03-24-2019, 12:29 PM

Quote:

Originally Posted by FireSale

General: 8.4 Mandatory when battery is relocated or as outlined in Class

Check the current class rules for your car. My guess is yes. Battery in trunk = rear deck mount cut off.

I thought that at first, but I'm not re locating. Just adding

Duster 7695 · 03-24-2019, 05:19 PM

Jeff,
You do need a cut off switch at the back of the car since you are putting a battery in the trunk.

Raul

FireSale · 03-24-2019, 05:27 PM

Quote:

Originally Posted by Jeff Stout

I thought that at first, but I'm not re locating. Just adding

It's just a switch.... Unless you are adding under the hood, put it in.

A stock battery location is under the hood. Install one anywhere else and a cut off would be required. When the battery is under the hood the power usually runs to a distribution block under the hood keeping the feed short and contained. When you add/relocate a battery in the trunk, you have 10-15 feet of vulnerable wire running under the car. The cutoff switch is meant to do two things, kill ignition and fuel pump power (fire control) and prevent any pinched or cut wire from shorting the chassis and blowing the whole friggin' car up with you inside.

Disclaimer: I am a bracket racer. I have a full cage, window net, neck collar and fire extinguisher in my 12 second car.

Anyone know the kill requirements for electric vehicles? Jeff Lane, you out there? I'd ask Garlits but I don't think he's around these parts much.

cmracing · 03-25-2019, 11:57 AM

Quote:

Originally Posted by Jeff Stout

If I have battery in stock location and add a second battery in back do I need a master cut off switch?
I think I don't but asking as I need to add a battery.

Yes! And if you want to wire this car "correctly" you will need a large constant-duty relay under the hood to disconnect the front battery from the rear switch........ Pain in the butt and extra cost, but well worth the hassle. I did an NHRA Stocker like this, the only "issue" is you need to remember to turn the main power off, especially after you put the car in the trailer. That constant-duty relay pulls a decent amount of power and will drain your batteries.........

Now, back to the battery location issue. I have a 2008 Buick Lucerne, stock battery location is under the rear seat. My 2015 Camaro has the battery in the trunk, from the factory, so do the newer Vettes.

These batteries are no relocated, wonder when the NHRA will start looking at these vehicles and making people put a switch in the rear of the car.

And what about those electric vehicles............

Dan Bennett · 03-25-2019, 06:44 PM

It's sort of a side step instead of a total thread derail, but I'm pretty amazed that no one seems to be concerned with batteries in electric cars.

Ever seen a vid on Youtube where some idiot shorts the battery of a vaping device and it goes into thermal runaway? Hellfire and carnage results.

Teslas use the same battery. But they have 8000 of them in their battery packs. Haven't heard a peep from the NHTSA, nor DOT for that matter.

03-23-2019, 09:19 PM	#2
Larry Hill Live Reporter Join Date: Oct 2004 Location: Hickory, Ky Posts: 10,635 Likes: 1,929 Liked 10,691 Times in 2,227 Posts	Re: Master Cutoff Switch The disconnect inside the car will not be affected by the outside disconnect being in the on position. The outside disconnect feeds the inside disconnect. w __________________ IHM Used Parts https://ihmusedparts.com 888-821-1817

03-24-2019, 11:27 AM	#4
Jeff Stout VIP Member Join Date: Dec 2001 Location: phoenix Posts: 1,486 Likes: 66 Liked 704 Times in 281 Posts	Re: Master Cutoff Switch If I have battery in stock location and add a second battery in back do I need a master cut off switch? I think I don't but asking as I need to add a battery.

03-24-2019, 05:19 PM	#7
Duster 7695 Member Join Date: Dec 2008 Posts: 140 Likes: 1 Liked 8 Times in 6 Posts	Re: Master Cutoff Switch Jeff, You do need a cut off switch at the back of the car since you are putting a battery in the trunk. Raul

03-25-2019, 06:44 PM	#10
Dan Bennett Member Join Date: Jun 2007 Posts: 438 Likes: 848 Liked 592 Times in 135 Posts	Re: Master Cutoff Switch It's sort of a side step instead of a total thread derail, but I'm pretty amazed that no one seems to be concerned with batteries in electric cars. Ever seen a vid on Youtube where some idiot shorts the battery of a vaping device and it goes into thermal runaway? Hellfire and carnage results. Teslas use the same battery. But they have 8000 of them in their battery packs. Haven't heard a peep from the NHTSA, nor DOT for that matter.