Alternator Kill Switch

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11secAvanti
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Alternator Kill Switch

Post by 11secAvanti » Mon Mar 25, 2013 11:47 am

Car has 16 volt system and kill switch in the rear kills the gnd from the battery. When I add a 16 volt alternator one wire it will tie into the B+ side of the kill switch. Will the engine continue to run since the alternator casing is its own independent ground and won't be killed? What is the wiring and or switching changes needed? Thanks.

11secAvanti
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Re: Alternator Kill Switch

Post by 11secAvanti » Mon Mar 25, 2013 6:20 pm

Never mind. I came up with a solution.

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Re: Alternator Kill Switch

Post by Kevin Johnson » Thu Mar 28, 2013 9:30 am

11secAvanti wrote:Never mind. I came up with a solution.

You might want to post up your solution because it might help others that find your topic in the future plus there are some highly experienced racers and brilliant electrical engineers reading that might see an issue. Always good to get a second pair of eyeballs on the problem.

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Re: Alternator Kill Switch

Post by 11secAvanti » Fri Mar 29, 2013 10:18 pm

I read the cabling wrong. The ground to the battery is permanent. The kill switch "opens" or "disconnects" the B+ line leaving the battery. The alternator wiring has to be on the correct side of the kill switch.

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John Wallace
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Re: Alternator Kill Switch

Post by John Wallace » Sat Mar 30, 2013 10:38 am

"Which is?"

Battery side of switch.
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Re: Alternator Kill Switch

Post by mbrooks » Sat Mar 30, 2013 10:58 am

Another save!

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Re: Alternator Kill Switch

Post by dwilliams » Thu Jun 06, 2013 8:12 pm

The alternator and battery need to remain hooked together. The disconnect goes between them and the rest of the electrical system.

If you disconnect the alternator from the battery while the engine is running, it dumps a huge load across the diodes. Diodes don't usually go up in smoke, they just start "leaking" backwards until the alternator doesn't charge any more.

Back when you could just pop the back off an old SI alternator and swap in a new $6 diode pack it was no big deal, but many modern alternators have *much* more expensive diodes, often spot-welded in.

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Re: Alternator Kill Switch

Post by jmarkaudio » Thu Aug 15, 2013 8:45 pm

Use this switch. Battery to one set of terminals, alternator to the other.

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Re: Alternator Kill Switch

Post by John Wallace » Fri Aug 16, 2013 8:17 am

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Re: Alternator Kill Switch

Post by justahoby » Fri Aug 16, 2013 3:58 pm

I read of a diode number to use from radio shack.... Turned out all empty...
So I wisely figured a different voltage/ amperage diode that was the same and not all over the Internet, they had plenty ..I can look it up if anyone interested if they got a stock type alternator leaving the motor running with the key off.
As I'm approaching 40,I still think I'm 20. What the hell is wrong with me?

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Re: Alternator Kill Switch

Post by justahoby » Fri Aug 16, 2013 4:10 pm

Here it is.. Te number at radio shack I forgot. But from keyed power to regulator ( again I realize this may be a different alternator form the OP but useful info) I used this.
The number Ipainted on it is: IN5400GI9644M (those are capital I not number 1s)

Don't know if this is helpful or not toady that read this thread and have a key off engine still running problem, but this diode worked for two years from letting it feed back and still working .
Remember the lined side towards regulator, and those using a gm internal regulator should use a form of resistance as well, like a ceramic ignition resistor, idiot light , or like I have a resisted wire from an ignition wire from an old points type ignition harness.
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As I'm approaching 40,I still think I'm 20. What the hell is wrong with me?

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