Rechargeable Proprietary Batteries
A proprietary rechargeable battery can have a lifetime of between 100 and 1,000 charge cycles, depending on the materials from which it is made. The types of batteries used in digital cameras generally last from 500 to 800 charge cycles, or about one to three years of average use. These are often quite expensive, as much as $50, and only work with a certain brand of camera.
As large proprietary batteries get older, the information in the LCD read-out about available battery power may not be accurate. Initially you might see that you have a full hour of power left; instead, the battery might last for only twenty minutes. This is a sign that the battery soon will not hold a charge and needs to be replaced.
In addition, they do have a limited lifetime, so expect to shell out another $50 for a spare battery and then another $50 every year or so.
Proprietary: This means that a device works only with one manufacturer's products. It is specific to that manufacturer. A proprietary battery, for example, generally will only work with a certain make of camera and may only work with certain models.