I've been using my device for about a month so far and the original rechargeable batteries are still going. It's been reporting 50% for several weeks, not sure if it will ever report anything else or if the next step is just offline. Anyway, I'm happy with it, and my original annoyance about it only reporting in C isn't so bad. I put a little note on it that says 2C-(2C/10)+32 and I'm actually getting quiet good at converting C to F
