As Alan said, they are the newer kit chargers, by Schumacher. We found a set of 4 chargers on ebay pretty cheaply. Once opened up, there are two circuit boards connected by a (i think) 5 pin ribbon cable. One board does all of the "work", while the other handles all of the control (switching between 2, 4, and 6 amp, and switching between 6 and 12 volts). We simply took the whole thing apart, added some extra wire to the ribbon cable, and mounted the front where you can see in this picture, and the back in a section behind the batteries - see
http://www.chiefdelphi.com/media/photos/35787 for details.
And yes, our batteries have names. Alfalfa, Bertha, Chester, Diana, Edward, Franklin and Ginny (I think... it's hard to remember). Sadly one of them (I think it was Bertha) took a 6-foot dive off another shelf during the build season, and was immediately labeled bad and set aside to be recycled. The big question though... what's the next name going to be?