Lead-acid battery terminal corrosion from road salt

Used as a real-world illustration of how trace chloride catalyzes a self-regenerating corrosion cycle on lead — Tom's mechanism for why halogen-activated flux residue destroys printed circuit boards.

Let me show you what happens. Unfortunately, this is not quite as intuitive as it used to be for students. It used to be intuitive because if you ever did any maintenance on your car battery, you would see this white deposit that forms on the lead terminals. This used to be the old types of unsafe terminals where you had a little post of lead sticking up and you had a clamp and you just clamped to it. Now we actually have a stainless steel screw cast into the lead terminal and you just tighten the screw up against the flat piece of lead. You can get the same corrosion, but they actually have rubber boots and stuff to keep the moisture out.