Floating grounds

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Floating grounds

Post by edvincent » Mon Nov 27, 2017 7:29 pm

Hi all,

In one of Jorge Menchu's articles he says that: 'when the engine is off, the battery is the lowest ground, when it's running, the alternator is the lowest ground'. I can't see why there is a difference, can anyone explain?

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Re: Floating grounds

Post by RYM6746 » Tue Dec 05, 2017 7:00 pm

I would imagine it is to do with the fact that the alternator is now supplying the car with all the voltage/current. Which means the current is flowing from the alternator positive (theoretical direction of current flow) through the battery and the rest of the car and back to the alternator ground (outer casing). I have completely disconnected a battery with the engine running and it carrys on running just fine. I will point out that all circuits become noisier due to the cushion effect from the battery being removed. I must say that this is just an observation on my experience and not a full blown conclusion.

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