Back during the beta test period, Magic Flight warned us not to totally deplete the Glyph batts. We could keep them topped off for better reliability. I found that the batts really dropped off quickly as they lost juice, so I would keep them charged up. I liked that feature as it insured great performance or none at all. After 6 months of daily use the batts had trouble holding a good charge. I bet if I had one of those digital high flatootin chargers my old batts would still be kicking.