All I can add is that my experience does not match yours. I use the Z9/800PF combo a lot. I have a second battery. I could have left the spare battery in the original packaging for all the use it has gotten. Nor do I recall seeing the battery below half-charged even after a considerable amount of use. Wish I could help you more. I suspect the difference lies in combinations of how-I-shoot vs how-you-shoot, and the number of comments and suggestions already made. That is, a complex interaction of factors.