These batts like a trickle type charge. Mine charges at 12v and 750ma. The wall type charger that came with my 1st box was 12v at 600ma and it did fine. I charged them overnite.
With my Hyperion 0610i I would use 12.0v. It asks for batt capacity in amp-hrs (ah) and these are usually 7.5amp-hr. I could charge at up to 7.5amps, but I wouldn't charge at over 1amp. You want a long, relatively low amp discharge from these and charging at high rates goes contrary to that.
I use a battery tender (float type charger) now and it stays on the charger all the time unless I'm going to be using it. No more getting ready to go somewhere to run only to realize my starter box batt is dead.