Proper Wiring for a Battery Disconnect W/Alternator

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Super1303
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Proper Wiring for a Battery Disconnect W/Alternator

Post by Super1303 »

The objective with the Battery Disconnect/Master Switch switch is to isolate the battery and provide, in essence, a 'Master off switch' for the car after an impact or incident to protect the workers and driver from a kinetic energy source and to shut off the car/vehicle completely.

What happens when you have a 2-pole Master Switch on a car with an alternator and you shut this switch while the vehicle is running?

-Most times the vehicle will continue to run as long as the alternator is live. (Lets forget about all the other details like voltage spikes, letting the magic smoke out, and stuff because if you have the proper switch this is not usually not a concern.)

So you shut the 2-pole Master Switch wired to the battery, pick a cable it makes no difference, and the car can potentially still be live.
Why? Because the Alternator is generating electricity if the engine is spinning, right? And that Electricity is being fed into you cars electrical system, after the switch, keeping it live until the engine stops turning. Wiring the alternator before the Master Switch would shut the car off, electrically, but it becomes a conflict with the idea of having a Master Switch since the alternator is still live.
Meaning it has power potential and is still a potential hazard.

To summarize, A 2-pole switch is used, typically, on a, internal combustion engine, vehicle without an alternator, generator, 3-phase stator, whatever you get the idea, and it's electrical system is fed battery power only.

Most of the cars I see on the hill run an alternator, so a 4-pole/post switch would be the proper 'Master' switch to use.
And is typically wired like this.

Image

My car is wired similar, the switch wasn't in the right location, but instead of the 10 GA wire running to the alternator it feeds a switch panel through a fusible link that powers the car. If the engine can't run the alternator can't produce power.
Something like this.
Image

A fusible link is also a great idea installed in the circuit where in the 10 GA jumper wire is shown, just in-case.
Image

It's ultimately the responsibility of the Driver of the vehicle to make sure his or her car is able to pass tech.

I tried to keep it short, if I missed anything fill in the blanks, I'd like to know.
I hope this will help clear up the difference's and provide a method too properly and simply wire up a 4-Pole Master Kill Switch/Battery Disconnect.
Hello, my name is Evan and I'm a Volksaholic.
1973 Super Beetle, #666
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