What brand of rechargeables are you using? I tried rechargeable alkalines (Pure Energy) and they only recorded around 3hrs straight out of the package (marked pre-charged) and only around 2.5hrs after the first charging and rechargeable NiMh's (Optex) wouldn't even turn the H2 on. (because of the lower voltage, I assume). I did change the battery setting in the H2's menu to NiMh.definitely use rechargeables. regular duracell/energizer batteries will work in a pinch but they won't last nearly as long as a single charge on a rechargeable battery.