TriX wrote:
Although Li-ion batteries do self-discharge very slowly, once they reach a certain low voltage threshold, the internal protection circuitry will prevent recharging without some real heroics, and unless you have the knowledge and equipment to “awaken” them and allow charging, they are essentially useless. Moral to the story is to periodically charge your batteries.
Hopefully that threshold is way below the point where my camera says "replace battery"!