Wiring Emegency shut off Switch

[sciff5]

Hey guys as my sig says I have an ls1/rx7 with a rear mounted battery and thus I have to have an emergency shut off switch to run at the track. Obviously I'm running the positive cable through the switch to the starter. I know if I just do that when I flip the switch the alternator will still keep the car running I know I need to run a 10ga cable from the alternator back to the battery positive cable but honestly I dont know which wire on the alternator to run back there, or why I'de run it back to the battery.

[sciff5]

bump trying to get her ready for track opening which is wednesday

[MIGHTYMOUSE]

you need to have the power sources (battery/alternator) on one side of the switch and the power users (acessory post, starter, etc) on the other.

the big wire from the alternator is the one you want. and it needs to be more like 4ga-2ga

[sciff5]

Originally Posted by MIGHTYMOUSE

you need to have the power sources (battery/alternator) on one side of the switch and the power users (acessory post, starter, etc) on the other.

the big wire from the alternator is the one you want. and it needs to be more like 4ga-2ga

Damn.. thats like 25 feet of 2-4ga wire running through my car. Thats a lot of resistence.

Alright second idea. Running a relay. How many amp relay would be ok to run

[MIGHTYMOUSE]

your starter or alternator both can move 150A or so

[ATwelveSec02Z28]

Im pretty sure without openning a rulebook you cannot use a relay or solenoid

[patriotformula]

Not to step on any toes, but I did some researching... 10ga is rated for 150 amps... However, because there are varying grades of wiring I went with 8 ga fine stranded for the alternator side of my kill switch...

[Mark98SS]

I went to the local welding supply house & picked up some #2 cable for an arc welder. Works good, real flexible.

[Chris@Straightline]

heres a good diagram of exactly what you need to do.

[sciff5]

I have my positive cable coming from the battery to the switch from the switch to the starter, from the starter to the alternator. So when I flip the switch it should kill power to the starter and alternator. The only thing is I believe is there is a red wire (like 18ga) coming from the alternator which I believe feeds the harness.. thats the one I think I would be able to disconnect with a relay. If I do that I think I should be set.

I think

[patriotformula]

Needs to be wired like Chris has it in the diagram, if you put the alternator on the other side of the switch it will keep feeding the car...

[sciff5]

Originally Posted by patriotformula

Needs to be wired like Chris has it in the diagram, if you put the alternator on the other side of the switch it will keep feeding the car...

Thats not too bad. So do I have to kill power to the harness too via that small red wire?

What size fuse do you guys rcommend?

[patriotformula]

I just wired my cutoff switch... I was wondering about the fuse size as well though. I didn't put one in mine.

[sciff5]

Wired my emergency shutoff switch as shown in the diagram and when I tried it the car kept running.


Battery positive terminal is wired to post 1 on the emergency shut off switch, the alternator is wired to that same post after I disconnected it from the starter.



On the other post I have the starter, and the fuel pump power wire.


Turned the shut off switch and she kept running like nothing happened. Only thing I can think of is that red wire (like 18ga) coming off the alternator into the harness is still providing power.

I could connect this wire to the switch too or run a relay but based on the diagram I shouldent need to play with it.

[Chris@Straightline]

Off the top of my head i cant rememebr exactly but that small red wire has something to do with making the alternator charge. When you wire it, the alternator and battery need to be on one side of the switch. and the starter and positive terminal for the car by the fuse boxes needs to be on the other. That way when the switch is thrown it completely cuts power to the entire car.

[patriotformula]

^ya what he said... If the alternator is on the same post as the wire that feeds the fuse box etc. the alternator will still juice the car without the battery's help. IF you have the alternator and battery on one post and you cut the switch then no power can physically make it back to the front of the car.

[Magic Man]

On the relay the rules say it has to be a direct wire back to the switch because the relay may stick or become forced on which would keep power applied to the car.

[sciff5]

Found out my issue

Ignition switch was wired to the alternator, just wired it to the same wire that goes to the starter.

Worked perfect. Thanks guys