I just picked up a Ctek battery maintainer/charger on Amazon. It's only 4.x amps but it has an equalize setting. Can't vouch for its effectiveness because it's new, but it cost about $70 delivered.

It claims to have an effective desulfation cycle. I have a 6a charger that's 1980's vintage, which I've been using as a maintenance charger on my home sump pump backup bank. That bank is almost never used and I'm hoping this new more sophisticated charger will squeeze some extra life out of those batteries. (My home sump pump backup is a 4,000 gph 12v bilge pump rigged to a bank of deep cycle batts that were retired from my boat, and are always on float charge in case AC power or my primary AC pump fails in a storm).

Link below.(nl)