Stainless steel bolts for electrical connections.

With an ss bolt you get 2 problems

1. chrome oxide layer
2. dissimilar metals plus electricity

Just what impact those have I wouldnt know.

NT

That's probably the one of interest.

Well, a typical ground connection on a car will be a plated brass ring terminal to the steel chassis. Most likely a steel nut welded to the back of the panel, and a steel bolt doing the clamping.

Is what I wondered if anyone could give chapter and verse on.

I'm no expert but a sailing friend often talks about the huge range of stainless grade and only a few are suitable for use in salt water. Stories include keels falling off due to using incorrect bolt grade.

So it seems there is scope for electrolytic problems with certain grades.

Perhaps he did not actually bolt the surfaces directly but put a nut in between so it was more like a terminal. That would cause corrosion I'd imagine. I found this out once many years ago on a lawn mower battery we used during the 3 day week back in the day, and I scuffled around to find some usable screws, and one must have been stainless, at least it was for about two weeks. :-) Brian

Any two dissimilar metals plus none pure water =galvanic action=chemical saltsformed that don't conduct as well as metal.

So cars are a big no no due to the salt used on roads.

Always made worse if there is electrical current from exterior source.

So the worst thing he could possibly do.

Metals that are far apart in the reactivity series are the worst, eg zinc and copper/brass. But aluminim and zinc not as bad.

Yes - that's what I did wonder. If it's merely used to clamp the terminal to a clean chassis there would surely be (near) zero current flow via the nut and bolt?