I bought this replacement battery around 2 weeks ago and have been very impressed by its performance so far. The battery pack uses Sanyo Eneloop cells and as a result arrived pre-charged. Even without a charge this battery was an equal to and if not was slightly superior to the original supplied. However after a couple more charges this battery pack has really surprised me with its longevity. On one quick charge it lasted a whole week at work. Although this use was not continuous (maybe 2 hours a day) I really do have to have the volume of this radio up quite high as I work in a noisy environment. Also it should be noted I was using it as a speaker for my iPod. All in all I would recommend this battery over the original supplied wholeheartedly.