Battery shelf life is the length of time a battery can remains in storage without losing its capacity. Even when not in use, batteries age. The battery's aging is generally affected by three factors: the active chemicals present in the cells, the storage temperature and the length of time it remains idle.https://www.google.com/search?q=definition+of+shell+life+a+battery&rlz=1C1IHCB_enUS722US729&oq=definition+of+shell+life+a+battery&aqs=chrome..69i57j0i546l3.13167j1j7&sourceid=chrome&ie=UTF-8?
I have measured voltages of several batteries every day (with exception of meetings, vacation in China) in more than 8 years. This graph is one of them (rechargeable Duracell(NiMh) in more than 2 years. The first point is the voltage at the first day when the battery was being charged. Each point is the voltage average of 4 batteries.
The 2nd picture is the raw data for a different battery started from 12/1/2021. Each number is the voltage measured on that particular day.
