RustStop Electronic rust protection and rust prevention.
Electronic Rust Inhibitor - dslreports.com
There are a million postings splattered all across the web, half of which say this works, the other half says otherwise. I doubt that the responses on this forum will be any different. One point that was made is that modern cars have such extensive rust protection, that such devices are not necessary. The concensious seems to be that these units are expensive add-ons , like undercoating, that are almost pure profit to dealers.
Almost all sea going vessels use a cathode system to keep the hulls rust free, but unlike ships hulls that are all continuous sheets of metal, with no gaps, supposidly the same type of unit will not work because cars have too many gaps in there body, even though the entire body is a continuous ground. One posting suggested that such units would only work if a car was completely submerged in salt water.
I doubt that this posting will dredge up any new info, other than what was sated in the original old thread, or is stated in the numerous threads spread across the internet.
A really good quote:
>Hi, I'm looking for a schematic to construct a anti rust device, to be
>fitted to a 12v car. Can anyone help?
I think they only work well with boats where the metal parts are
always in contact with the water. The idea is simple and only takes
an op amp and perhaps driver transistor. You measure the voltage
being produced by the galvanic action of dissimilar metals and apply
enough current to another electrode to cancel the galvanic voltage.
Unless all the parts are bonded - connected together electrically - it
won't work. Unless the electrode and parts being protected aren't wet
at the same time by the same electrolyte, it won't work.
If it were that easy - you could just bolt a sacrificial anode (zinc)
to the car and be done with it - that technique has worked well for
many years in boats.
Things to search for are "active cathodic protection"
I knew a guy with a boat who was paying the dockmaster to look after
it. He complained that the zincs, he added, where being eaten away in
no time - and plating out on the bronze parts below the water line.
So I went out to look at it - it had an active rust prevention scheme
already in place. That suggests, to me, that had he had galvanized
fittings below the water line they might be eaten away leaving the
iron exposed - but I don't know for a fact. I just told him to use
one system or the other, but not both.