NHRA Remote Batter Disconnect Switch

[bfarroo]

Has anyone hooked up a remote disconnect switch per NHRA rules in their car for mounting the battery in the hatch? Specifically I know I can run the wiring from the remote battery through a disconnect but the switch will not shut down the motor once it's running. I'm thinking one of the disconnect switches with a auxillary contact running a secondary relay to disconnect the power to the electronics.
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[BadAssPerformance]

Per the rules, any battery relocation requires a rear vehicle mounted and labelled switch that cuts all power to the vehicle. Typically wired like:

Batt (+) --> switch --> main power tap (including fuel pump and ECU)

So when you flip the switch, the ECU and fuel pump are de-energized... if yours doesn't kill it, then thats maybe cuz you didn't break the circuit from the alternator?

[moparman76_69]

Per the rules, any battery relocation requires a rear vehicle mounted and labelled switch that cuts all power to the vehicle. Typically wired like:

Batt (+) --> switch --> main power tap (including fuel pump and ECU)

So when you flip the switch, the ECU and fuel pump are de-energized... if yours doesn't kill it, then thats maybe cuz you didn't break the circuit from the alternator?

Yeah I can disco the battery in the van and the alt will keep it running.

[22shelby]

you are going to have to also wire in a heavy duty continuous duty relay like a snow plow relay to pass the alt field wire thru.... then avtivat the relay via the batt disconect switch.... ill draw a diagram here in a few minutes

[shadow88]

Or have the relay interrupt the ASD relay as well as battery power.

EDIT This is from the 2008 rulebook.

Mandatory when battery is relocated or on any vehicle running
9.99 or quicker. 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.

[bfarroo]

Yeah that's pretty much what I found. I'm wondering if I can either cut the ASD power as this would kill the electronics or use a high amp relay to switch the entire fuse box power feed wire. Either adding a regular 30amp relay to the ASD circuit wiring, or extending the ASD wiring to the hatch and running them directly through the secondary contacts on the disconnect switch would be easy enough. The current wiring in the daytona is just for the rear mounted battery, I do have circuit breakers installed front and rear but it's basically in parallel with the alternator like the stock wiring is. It would seem like a lot more work to run a cable from the alternator to the battery, then to the disconnect switch, then back up to the front of the car.

[BadAssPerformance]

The intent of the rule is not to just cut the power to shut the engine off, but instead to break the (+) circuit of the power system so that, lets say the car is upside down and on fire, the insulation is burned off several wires, the main (+) circuit is broken with the switch

[22shelby]

^^ right...its to remove all elecrticity from the vehicle... there are many ways you can cut power and kill the motor... i.e. the 14DB wire going into the ECU is you power feed for the computer, cut the circut, shut the computer off kills the motor.... 14DG coil feed wire will do the same, cut the power off to the coil, kills the motor.... all these can be done from a HD sol/relay... i am currently doing the same thing per NHRA rules, and my disconnect will provide direct feed to the MSD ign. box, kill the power on the box, kills the motor...

oh and im planning on a dash kill switch too for the car, something to think about ;)

37254

[BadAssPerformance]

Need to add the alternator to your circuit diagram there...

[22shelby]

thats what one of the firewall passthrus are for... one for the alt, the other for the starter... all my electrical is going under the dash fuse box and all...oh and the ground is most likely going to be a direct mounted stud going thru the fire wall, no rubber grommet

edit... oh i see now, yeah your right.... ok... back to the drawing board...lol i thinkg if i just redirect the alt (+) directly to the battery, that should work...

[BadAssPerformance]

right...

[bfarroo]

I can understand the idea of wanting to kill the power to the wire so it can't short out and catch on fire. I was a MECP certified automotive electronics installer for a few years while going to colleage for electrical engineering. God knows I've seen way to many burnt up cars from people installing wiring for a stereo without fuses. What I don't understand is if you crash the power is not going to be cut until emergency crew member X runs down the track and flips the switch. If the wire is shorted it will be burnt to a crisp long before anyone gets to the switch. Having a circuit breaker installed will instantly kill the power if the wire is shorted. I'm all for the safety but the approved execution is strongly questioned. I think I'm going to start with the battery disconnect and interrupting the ASD circuit and go from there. This will remove any safety aspects of shorting the wiring/battery and will also kill the car when flipped.

[ATaylorRacing]

This is why I am happy keeping my battery up front to help with traction!

[Warren Stramer]

I can understand the idea of wanting to kill the power to the wire so it can't short out and catch on fire. I was a MECP certified automotive electronics installer for a few years while going to colleage for electrical engineering. God knows I've seen way to many burnt up cars from people installing wiring for a stereo without fuses. What I don't understand is if you crash the power is not going to be cut until emergency crew member X runs down the track and flips the switch. If the wire is shorted it will be burnt to a crisp long before anyone gets to the switch. Having a circuit breaker installed will instantly kill the power if the wire is shorted. I'm all for the safety but the approved execution is strongly questioned. I think I'm going to start with the battery disconnect and interrupting the ASD circuit and go from there. This will remove any safety aspects of shorting the wiring/battery and will also kill the car when flipped.

Benji, One other option you have is to use a constant duty solenoid (80 amp minimum) for the main batt. supply, with the control side switched by a simple toggle switch that you mount at the rear bumper area. that way you dont have to run so much heavy cable to required outside cutoff switch.
Also with this system you can wire a ford style inertia switch in series with the toggle sw. If you crash the inertia switch shuts everything down.
NHRA wants to be able to shut the car off at the starting line in case of a leak or some other problem the driver or crew are unaware of.
As discussed in another thread the Ford inertia switch has not inadvertantly shut my car down, even with 1.5 short times.
Also, I had NHRA div. tech man give me the OK on the setup. Hope this helps somehow.

[BadAssPerformance]

Good info! :thumb:

[bfarroo]

I'm finally getting the switch installed this weekend. Does anyone know what wire the ADS power feed wire is on a SBEC car? I found a TBI diagram which lists it as terminal 3, RD/WT. I would think it would be the same with the turbo car but want to make sure.

[Ondonti]

Benji, One other option you have is to use a constant duty solenoid (80 amp minimum) for the main batt. supply, with the control side switched by a simple toggle switch that you mount at the rear bumper area. that way you dont have to run so much heavy cable to required outside cutoff switch.
Also with this system you can wire a ford style inertia switch in series with the toggle sw. If you crash the inertia switch shuts everything down.
NHRA wants to be able to shut the car off at the starting line in case of a leak or some other problem the driver or crew are unaware of.
As discussed in another thread the Ford inertia switch has not inadvertantly shut my car down, even with 1.5 short times.
Also, I had NHRA div. tech man give me the OK on the setup. Hope this helps somehow.

In case this thread is easier for people to search for, found it when looking up kill switch rules on google.

I have a continuous duty solenoid and a real Moroso metal switch in the rear (but only rated for a low amp carb'd car). Because the solenoid eats battery when energized, I have it wired to turn off when key off, and then to start the car I have to first energize the solenoid with a momentary switch. Once the solenoid is energized it won't turn off until key off. This means no memory functions for me unless I wired in something outside the kill system. My boost controller has a memory function and it pulls ridiculous amperage so I may never worry about it. Its for some sorta learning function that I might not care about (not boosted not to even be able to test).

I also have a 100 amp breaker before the solenoid.

[bfarroo]

I ended up wiring everything through the switch. Alternator wire runs front to back and ties to the battery. Power leaves the battery goes through the switch and back up front to supply power to the electrical system. I also installed a circuit breaker up front to protect the wire feeding the battery from the alternator and another circuit breaker at the battery to protect the wire feeding the car electrical. The car shuts down when the switch is flipped.

[contraption22]

Lots of good info here. Thank you all contributors.

- - - Updated - - -

Lots of good info here. Thank you all contributors.

[Reeves]

Looks like I'm going to be doing the same soon. Like Benji did. Thanks for the info.

[zin]

Also with this system you can wire a ford style inertia switch in series with the toggle sw.

If you crash the inertia switch shuts everything down.

As discussed in another thread the Ford inertia switch has not inadvertently shut my car down, even with 1.5 short times.

Also, I had NHRA div. tech man give me the OK on the setup. Hope this helps somehow.

This is a great idea, one of those "I don't have to do anything" safety devices, like automatic sprinklers.

Missed it the 1st read through...

Mike

[rbryant]

What about running a really small AGM battery up front like 5Ah or so that activates a remote starter solenoid that connects the main battery in the rear.

That way at the track if they disconnect your little front battery it shuts the car off, the other main battery is "for my stereo." :)

I was thinking about doing this to avoid the stupid rear switch.

-Rich