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wiring a 2 pole kill switch

EFI Wiring Fundamentals

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Discussion and questions related to the course Motorsport Wiring Fundamentals

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i have a 2 pole kill switch i want to wire it in a proper way in order to prevent voltage spike that may cause the alternator to be damaged.... is it okay to connect the +12v batt and the alt charge cable on one pole and the other side will go to the starter and to the +12v collector? the car is bmw e36

I've used that technique before. Some racing organizations don't like that becasue the alternator output is still hot with the master switch off.

If that is a problem, then get the master switch with the two extra poles (one Normally Open and one Normally Closed with the Switch off). Wire a 5 ohm large wattage resistor to the normally closed, so that when the master is turned off the switched side power is grounded through the resistor. Wire the Normally Open, to the Ignition Power to the coils. This will stop the engine when the switch is turned off. And any excess alternator power is dumped through the resistor.

u mean that there is no way to disconnect the battery from the whole car with preventing the voltage spike in 2 poles kill switch?

You could have two switches. One as the external "kill" switch (wired as you currently do), and one right on the battery (only used when you want the battery completely isolated.

thanks david

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