On Tue, 12 Apr 2016 10:26:56 -0400, Ed Huntress
wrote:

On Tue, 12 Apr 2016 09:50:23 -0400, Bob Engelhardt
wrote:

On 4/12/2016 9:18 AM, Ed Huntress wrote:
...
The way it works is that the anode/cathode (the cathode is
the steel, iron, aluminum alloy, brass or bronze) combination forms a
battery, and the anode material is "eaten" away as the "battery"
conducts electricity. The water is the electrolyte.
...

Right! And where is the electrolyte in a car?

Bob

I assume it's an intermittant thing: when the area is wet, you have an
electrolyte. When it's dry, you don't have to worry about corrosion,
anyway.

Again, I haven't seen it used on a car. I'm guessing about how it
would work in practice.
The part that is going to rust can be wet and salty while the anode
location is clean and dry.

It's been tried - the results are not encouraging - not worth the cost
and effort of installing, generally speeking.