Its not just the copper pipe but all metallic parts exposed to the H2S , the galvanised cable tray, engine, electrical terminals, the inside of the hull etc. I think you have a bigger corrosion problem than you imagine.
The tell tails on the batteries are useless. They are not floating balls anymore, just a pointed plastic stub, when the end dips in the acid it causes total internal refraction of the light so it shows green. When the acid is low, no refraction so shows black.
As the acid level rises as a battery charges, green is supposed to mean OK and charged, totally misleading, just make folk wreck their batteries faster.