I used POR-15 on a battery tray in an old Mb. Preparation was to rinse off the acid, rinse again with a bi-carb solution, rinse again w/water, wash and rinse with bicarb, letting it sit this time. yada, yada , yada. let dry with a heat lamp for three days, paint with por15. Install one of those yellow battery acid pads and the battery. This was 3 years ago. Recently noticed battery was leaking and removed it. Battery pad was pretty well soaked. Removed it. Now, the POR15 was basically flaking off in big slabs like GM paint but not much damage occurred. I've started the rinse business again but am going to try rust-bullet this time. Won't be a good test since I am replacing the battery with an Optima. This isn't a bad-mouth of POR-15, you do have to prep carefully per their instructions; I did not use the metal wash they spoke about. Other things I've POR-15'd are holding up well but they are not subject to battery acid.