Sony UWP-D27 2-Person Camera-Mount Wireless Omni Lavalier Microphone System (UC90: 941 to 960 MHz) - Manual (Page 64)

If the battery terminal is dirty, you may not be able to turn on the product or the battery pack may not be properly
charged. In that case, clean the battery by lightly wiping off any dust using a soft cloth or a cotton swab.
How to store the battery pack
To maintain the battery pack’s function, charge the battery pack and then fully discharge it in the camera at least once a
year before storing it. Store the battery in a cool, dry place after removing it from the camera.
On battery life
The battery life is limited. If you use the same battery repeatedly, or use the same battery for a long period, the
battery capacity decreases gradually. If the available time of the battery is shortened significantly, it is probably time
to replace the battery pack with a new one.
The battery life varies according to how the battery pack is stored and the operating conditions and environment in
which each battery pack is used.
5-021-699-11(1) Copyright 2020 Sony Corporation
64