The reality of batteries is that unless you have back-ups (or the option of plugging into AC), when they poop out, it's a wrap. Game over. And while it's a common practice (not to mention common sense) to have multiples of critical power supplies on hand when shooting on assignment, you never hear anybody complain about their batteries lasting too long. If anything you're more likely to hear praises to the Lord for sustaining the power supply through the last moments of the last scene. Fortunately, battery technologies continue to evolve rapidly and the benefits of these new technologies are evident in some of the newer batteries manufactured by Anton/Bauer and IDX.