I am very experienced working on old cars, but not experienced at all with large home RE battery packs, so take this with a grain of salt...
Ever notice the only vertical surface in your home that collects dust is the face of the TV? The invisible electromagnetic field draws the dust.
A cars battery is vented for when it get hot, and the battery terminals weak and invisible field draws the sulphuric vapors to the post, causing corrosion. Lead will be whitish, and copper will be greenish.
I take the clamp off, clean everything thoroughly, re-attach, then smear grease over both the posts. It works for me (on old car batteries).
I have heard from old heavy equipment mechanics that they have poured Karo syrup over the post, which dries into a crust, but I have never tried this.
"Now I know why tigers eat their young"! -Rodney Dangerfield in "Caddyshack" when observing the bosses son.