Actually Group 31 are about 130 but wait there is more (27/29 are about 100)
Most of the "Group xx" batteries out there are either straight up starting or MARINE/deep cycle.. these batteries should be kept fairly full for best life. Rapid againg sets in around 75% (M/dc) or 80%(Starting) where as a TRUE Deep Cycle can go to half full before that happens.. or so they say. NOTE there will be differences berand to brand. Also the ability of the battery to recover from an "OH C**P!" level run down (like the volt meter has only one digit run down) is better with the DEEP CYCLE.
GC-2 (Golf Car, takes 2 to make 12 volts) and GC-12 (Golf Car, 12 volt) are DEEP CYCLE batteries.
LiFePo4 is even better, and more costly and other things that matter some good some not so much... (I'm just starting to play with those)