Kill switch

Discussion in 'Electrical & Stereo' started by SMOKEDYA, Sep 21, 2013.

  1. SMOKEDYA

    SMOKEDYA Active Member

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    I posted this on our fb page as well. My question is anyone have a push/pull kill switch? If so care to show pics and also did you go threw the tail light or the bumper? My other question is just to verify.The + from battery goes to one side of the switch and to the same side of the switch you also connect the + off the alternator. Then on the other side of the switch you run a wire to the + on the fuse box under the hood. Correct?
     
  2. Suspect

    Suspect Well-Known Member

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    i went through my taillight. i think mines + to switch same side + to fuse box. id have to look its been a long time.. either way itll shut off, just might end up with pull off. swap and it should be push off.
     
  3. MustangChris

    MustangChris Legend Retired Staff SN95 Supporter

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    you can get a diagram from your local track, but here's one i tracked down online...

    [​IMG]
     
  4. Pete@FTR

    [email protected] Active Member Preferred Vendor

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    +1 to this ^ Gotta love that MS paint schematic haha
     
  5. SMOKEDYA

    SMOKEDYA Active Member

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    So + battery goes to the starter,not the fuse box? How does the car get power then? Or do you still run power to the fuse box from the starter then? I have wired up my foxes the way I described above,just want to double check cause the SN's have built in solenoids in the starters.....
     
  6. MustangChris

    MustangChris Legend Retired Staff SN95 Supporter

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    we'll have to wait until a 5.0 expert like [MENTION=17007]RichV[/MENTION] chimes in.... the 96+ have built in solenoids, but im not familiar with 5.0s.
     
  7. ttocs

    ttocs Legend

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    assuming the starter/fuse box are tied together that should kill power to the car. The only thing I would add is that it shows a fuse between the alt/switch, there should be one 12" from the battery as well. Otherwise if you have a wreck, even with the switch turned off that cable would still be live and if it shorts it will either weld itself to the chassis or worse... rule #1 in automotive electronics - always fuse 12" from the battery. Rule #2, refer to #1.
     
  8. RichV

    RichV Well-Known Member

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    I don't have a push/pull, mine is a standard rotary mounted next to my steering wheel.

    You will need a 4 pole, two large lugs will be for the battery. The smaller lugs will be for the charge wire. Follow the heavy gauge out the back of the alternator, it will connect to a terminal on the fusebox. It's on the driver side strut tower. I disconnected there and ran out of the alternator through the kill switch, back to the terminal at the fusebox. The battery cables are a no brainer, just run them through the big terminals on the switch.

    You're doing this for NHRA?
     
  9. SMOKEDYA

    SMOKEDYA Active Member

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    yes NHRA requires it to kill the engine plus all power.
     
  10. Pete@FTR

    [email protected] Active Member Preferred Vendor

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    Basically you need the + on the battery and the + on the alternator behind the switch in the circuit (not parallel with anything).
     
  11. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    Dredging this thread back up, I have a couple questions. I've done some looking on-line and there seems to be several different ways of doing this. I am doing this in conjunction with a battery relocate (to either the trunk or rear seat area, not sure yet). The ones I have found/am interested in are:

    Option 1
    This seems to be one of the more common options found via the Google; using a 2 post switch: extend alternator wire to one post. Connect the battery + to this SAME POST. Run the starter power feed to the 2nd post, run the fuse box power feed to the second post. Circuit breakers will most likely be needed in the alternator run, starter run, and maybe fuse box run? Circuit breakers will probably need to be at least 150 Amp, maybe 200 Amp. This has the disadvantage of requiring more runs of hot wires. Also, there is a lot of talk online about spikes to the alternator when power is suddenly disconnected and it destroying stuff - is this an issue with this set up?

    Will any 2 post switch work? Does the switch need to be able to handle the amperage from the alternator?

    Option 2
    What has been suggested in this thread; use a 4 post switch: extend the existing stock battery cable to one large terminal on the switch. Connect the other large terminal to the battery. Find the alternator charge wire, remove from fuse box and run it to one of the smaller terminals on the switch. Run the last smaller terminal to the fuse box (where the alternator used to connect to). Turning off the switch (or breaking it) will disconnect the battery from the existing car battery cable, and will disconnect the alternator from the fuse box. This has the advantage of not running as many wires from the engine bay to the cut off switch to the battery.

    A candidate switch for this is the Longacre HD Disconnect switch (#47582). However, this is listed as supporting 125 Amps on the B terminals (the smaller terminals for the alternator). What happens if I am using a 130 Amp or great alternator? Does that mean I blow the switch?

    Option 3
    This one is touted as the "right" way to do this. I don't really know, which is why I am asking here :) Use a 6 post switch (like the flaming river combination battery and alternator switch, part #FR1013); The battery goes to one large post; the starter, alternator and fuse box goes to the other large post. There are two sets of 2 small terminals (for a total of 4 small terminals). One set connects/breaks a connection between IGN (+12v) and the coil positive; the second set connects/breaks the starter/alternator/fuse box to ground. When the switch is on (battery is flowing), the first set of terminals connecting the IGN and coil is connected, the shunt to ground is closed. When turning off the switch (breaking it), the first set of terminals (IGN and coil) is broken, and the start/alternator/fuse box is shunted to ground with a resistor in place to trickle the power down and not spike voltage.

    This might sound confusing, so here's some pictures:

    [​IMG]
    [​IMG]

    This is by far the most complicated of Options, but not impossible. Disadvantage is there are more wires to run than the other options, and I have to re-wire the coil connection a bit. Advantage may be is this is the nicest to electrical components and computers? It essentially relies on turning off spark (via the coil) to kill the engine, and then disconnects the battery from the system. Also, I don't think the amperage of the alternator affects anything here, correct?

    I'm not looking for the "easiest" to do - I'm not afraid of work. Having said that, we might all agree that Option 3 is technically the best way (for example) but there is nothing wrong with Option 2 (for example), it works, and is easier than Option 3, so just do that.

    Lastly, the switch I would "like" to run is the Flaming River one I mentioned in Option 3. If we all agree that Option 2 is the way to go, than I have to select a different switch (which won't kill me). And it's probably a good idea, regardless of which Option is selected, to fuse/circuit break the wires to the battery, yes?

    Thoughts on each of the Options? [MENTION=17007]RichV[/MENTION], [MENTION=9209]ReplicaR[/MENTION], [MENTION=10532]MadStang[/MENTION], others - what do you guys think?
     
  12. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    Bueller? Bueller? Bumpers. I may need to create a new thread...
     
  13. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    The view count on this thread has not moved. Creating a new thread. Disregard here.
     
  14. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    Some More Cut-off Switch Questions

    Hey guys, I posted this in an old thread, but it wasn't getting any action (and/or I am being impatient), so creating a new thread. There was some discussion in a Kill Switch thread on a way of wiring it up. I haz teh questions. I've done some looking on-line and there seems to be several different ways of doing this. I am doing this in conjunction with a battery relocate (to either the trunk or rear seat area, not sure yet). The ones I have found/am interested in are:

    Option 1
    This seems to be one of the more common options found via the Google; using a 2 post switch: extend alternator wire to one post. Connect the battery + to this SAME POST. Run the starter power feed to the 2nd post, run the fuse box power feed to the second post. Circuit breakers will most likely be needed in the alternator run, starter run, and maybe fuse box run? Circuit breakers will probably need to be at least 150 Amp, maybe 200 Amp. This has the disadvantage of requiring more runs of hot wires. Also, there is a lot of talk online about spikes to the alternator when power is suddenly disconnected and it destroying stuff - is this an issue with this set up?Will any 2 post switch work? Does the switch need to be able to handle the amperage from the alternator?

    Option 2
    What was suggested in the Kill Switch thread; use a 4 post switch: extend the existing stock battery cable to one large terminal on the switch. Connect the other large terminal to the battery. Find the alternator charge wire, remove from fuse box and run it to one of the smaller terminals on the switch. Run the last smaller terminal to the fuse box (where the alternator used to connect to). Turning off the switch (or breaking it) will disconnect the battery from the existing car battery cable, and will disconnect the alternator from the fuse box. This has the advantage of not running as many wires from the engine bay to the cut off switch to the battery.

    A candidate switch for this is the Longacre HD Disconnect switch (#47582). However, this is listed as supporting 125 Amps on the B terminals (the smaller terminals for the alternator). What happens if I am using a 130 Amp or great alternator? Does that mean I blow the switch?

    Option 3
    This one is touted as the "right" way to do this. I don't really know, which is why I am asking here :) Use a 6 post switch (like the flaming river combination battery and alternator switch, part #FR1013); The battery goes to one large post; the starter, alternator and fuse box goes to the other large post. There are two sets of 2 small terminals (for a total of 4 small terminals). One set connects/breaks a connection between IGN (+12v) and the coil positive; the second set connects/breaks the starter/alternator/fuse box to ground. When the switch is on (battery is flowing), the first set of terminals connecting the IGN and coil is connected, the shunt to ground is closed. When turning off the switch (breaking it), the first set of terminals (IGN and coil) is broken, and the start/alternator/fuse box is shunted to ground with a resistor in place to trickle the power down and not spike voltage.

    This might sound confusing, so here's some pictures:

    [​IMG]
    [​IMG]


    This is by far the most complicated of Options, but not impossible. Disadvantage is there are more wires to run than the other options, and I have to re-wire the coil connection a bit. Advantage may be is this is the nicest to electrical components and computers? It essentially relies on turning off spark (via the coil) to kill the engine, and then disconnects the battery from the system. Also, I don't think the amperage of the alternator affects anything here, correct?

    I'm not looking for the "easiest" to do - I'm not afraid of work. Having said that, we might all agree that Option 3 is technically the best way (for example) but there is nothing wrong with Option 2 (for example), it works, and is easier than Option 3, so just do that.

    Lastly, the switch I would "like" to run is the Flaming River one I mentioned in Option 3. If we all agree that Option 2 is the way to go, than I have to select a different switch (which won't kill me). And it's probably a good idea, regardless of which Option is selected, to fuse/circuit break the wires to the battery, yes?

    Thoughts on each of the Options?
     
  15. ttocs

    ttocs Legend

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    Will any 2 post switch work - I will have to say no on that as there are some that are not made to handle any current on them and will melt if you run your ignition through them. I don't think you need the 200 amps your talking about in your breakers but you definitely do not want to get some stupid 10 amp switch.

    So what is more important here the switch or the wiring you run?
     
  16. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    Hey ttocs, I created a new thread on this because I thought this was burried and no one was seeing it. Feel free to merge them back if you want, or if some mod wants to.

    To answer your question, the switch I'm interested in is rated at 150 Amps continuous, with a 2000 Amp surge. It it an Option 3 type switch, so it's alternator provision is rated at 120 Amps.

    In the end, I care more about the wire. Having said that, I care about the switch too because if I'm hitting that switch, $hit has hit the fan. I prefer a push-off style. So if the answer is "any of the wiring options above will work equally well" then I'll select the one that let's me use the switch I want. If the answer is "Option 2 is the best" then I guess I'm looking for a different switch.

    My question, ultimately, is which of the above wiring method options is preferred/works/is the best?
     
  17. ttocs

    ttocs Legend

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    ah ok. I am not trying to be difficult but I am not sure how to rate one better then the other assuming that they both turn the motor off and kill the battery wire, short of what the difference in cost is. Obviously the switch you want and how it actuates is important and there is no reason that cannot dictate what you use. Its just a matter of figure out what is more important to you and then go for it. I would not let the number of wires you have to run scare you as if you prepare for it and prep a pre-made harness outside of the car you can run them all at once and its neater/cleaner anyway.
     
  18. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    Oh the number of wires doesn't bother me, I'm totally prepared to do Option 3 if necessary. I guess what I am asking is this: of the 3 options on how to install a kill switch, is there any difference? Do any of the options just flat out not work? Do any of the options create a fire hazard? Do any of the options destroy your alternator/computer when the switch is hit? Or are all 3 options basically the same, meaning they all accomplish the same thing, they are all about equally safe, just do which ever one you want?
     
  19. ttocs

    ttocs Legend

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    I don't see any of these causing a problem that I can tell as long as everything is fused/circuitbreakered correctly but this is one wiring element that I have not actually done myself. I am more into the security/stereo area then the drag strip but its not outside of my understanding either. Not sure who to direct you to either but now that I think about it I might be doing this on a friends car this winter... This is one of the many points you will find in the custom world where there is more then one way to skin a cat and its just a matter of picking what is most important to you.
     
  20. mcglsr2

    mcglsr2 Well-Known Member SN95 Supporter

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    Alright, I appreciate the response. [MENTION=17007]RichV[/MENTION], [MENTION=9209]ReplicaR[/MENTION], [MENTION=10532]MadStang[/MENTION], any insight?