John,
Here's the Fullriver battery model I recently installed two-of in our rig. Notice that it's recommended float voltage exactly matches that of stock RV converters so that it's not necessary to buy another charger for one's RV using these batteries ... hence they don't get ruined from a too-high float voltage. Due to their low internal resistance, these two batteries also charge fast enough for our camping style using just our stock RV converter:
http://www.fullriverbattery.com/product/batteries/DC115-12Here's a document explaining how to charge them. Note the far right portions of the charging stages graphs, where they give the equations for, and show, the small amount of tapering current flow that occurs as they approach a full charge:
http://www.batterien-mueller.de/uploads/media/Fullriver_Lade-Anweisung.pdf