Got it, people like having a 2nd battery.
To be clear, I never questioned spending $100, the question was taking up more space in my already crowded dry storage area that's filling up with stereo related stuff. Anyway, I understand the value of a 2nd battery for helping prevent the battery from draining when the engine was off. My real question was, is there ever a point where one battery isnít enough even when the engine is running? But, now that I think about it, I guess thatís more of an alternator question since the issue would be not being able to keep the battery charged as fast as itís being drained. Hmm, I'm pretty sure I'm not near that limit, so I'll retract the question! Thanks for the replies.