This is exactly the point I'm trying to understand, and get an answer
for. Our regional rules (CASC) state that the main cut-off switch must cut
off the alternator as well as the battery, and I'm trying to figure a way
to do that. Lot's of people run alternators, so some-one must have figured
this out...:)
Brian
At 12:34 PM 3/19/02, you wrote:
>Brian:
>
>I haven't actually tried that, as it could damage the electronic ignition,
>rev-limiter, and tach. I have my main cut-off switch between the battery
>ground terminal and the chassis, disconnecting the battery only. If you
>disconnected this switch with the engine running, this would be similar to a
>condition known as "load dump". In this case the alternator tries to charge
>an infinite load. With the battery disconnected, the alternator voltage
>output rises (also due to the fact its a huge inductor), and the voltage can
>go as high as 120V for a brief spike. This would almost certainly fry any
>and all 12V devices connected.
>
>The main power cut-off switch does not disconnect the alternator from the
>rest of the electrical system, nor was that its intent. The ignition switch
>is still the best and only way to shut off the engine. You bring up an
>interesting issue, however. You would have to wire another heavy duty relay
>(like a standalone starter solenoid) between the main alternator output and
>the vehicle electrical system, with its coil energized via the cut-off switch
>to also disconnect it with the external cut-off switch.
>
>Regards,
>Myles
Brian Evans
Director, Canada
MCI Wholesale Internet Services
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