@Herbhornist : Actually, this is not quite true. You can replace the battery easily enough, but you need to have access to Genie 2 because you have to re-calibrate the battery’s capacity in that program. You can’t just pop the battery in, and resume operation because everything has to be recalibrated due to the additional capacity of the battery due to its newness.
(The newness of the battery contributes to its capacity, but not vice versa.)