Two games I remember having that had save via battery were Tecmo Superbowl and Baseball Stars. I never had a problem with TSB, but we bought Baseball Stars used and there were a few times when we lost all our save data. I'm guessing that had to do with an old battery. We were so frustrated when that happened. My brothers and I would spend so much time creating our teams and building up the players to the point where every guy was 100% in every stat.