Kill switch on a generator car (Page 2 of 2)

Jumping in on this late.

The problem for an Alternator or a generator is that its spinning and making volts, which then power the engine side of the harness, and so even when you cut off the battery, the Alt / Gen still keeps everything running.

The Lemons rule does not specifically state that the Alternator output (which connects to the Battery +) must be disconnected. The rules says the engine has to stop running, which should (should!) stop oil and fuel from pumping, but that does not stop oil/fuel leaks from broken s&*t. The INTENT is to have all power sources in the engine bay (CAR!)  be cold (0 vdc). Hot connections can lead to sparks, sparks plus spraying oil or fuel = fire. I know there are many cars which do not disconnect the Alternator from the battery and get away with it.  I bought a car like that and nearly welded a 8mm wrench to the engine block when I was removing the Alternator.  I installed a 4 pole kill switch.

I know there are a few cars, which power their go pro cameras and radios from the battery direct. This does not meet the overall rule of everything off, but  its probably OK, as its a 5vdc line for the go-pros, and having the radio ON for comms is maybe helpfull. BUT I am not the chief inspector, so my opinion is not the law.

Ways to make it stop with a 4 pole kill switch.
Obviously the main battery cable goes To/From the main (big) connections on the 4 pole switch.

1. Run +12 vdc to the small switch terminals, then to the Coil. When the switch opens the coil has no power and the car will die.

2. Run +12vdc output of the Alternator to the kill switch, then connect it to the everything else side of the kill switch. In this case you want to put the resistor on the Alternator side of the switch and ground it. It will use a little power from the alternator all the time, but it protects the alternator when you switch the kill switch.

3. Run the switched +12vdc to a DPDT relay coil and to ground. Run the Alternator +12vdc output to the common switched input to the relay. On the NC (normally close, aka non-energized position) put the resistor to ground. Connect the NO (normally open) connection to the switched side of the big +12 vdc of the kill switch. This connects the Alternator to the battery when the Kill switch is ON, and connects the Alternator to a resistor when its OFF. And it does not waste any electrons in generating heat in the resistor during normal car running.

4. connect the generator field +12vdc through the small contacts on the kill switch. When the kill switch is OFF the generator field is 0 vdc and the generator will not generate.

Test what every you do to make sure it kills the engine and has no +12VDC in the engine bay with the Kill switch off.