IT Concepts X2U Instruction Manual page 10

Avoid touching the battery contacts with wet hands.
Should the device not be used for a longer period of time, remove the battery
from the device and store it in a dry place.
Notice
Charge the battery fully before first use or after a long period of storage.
If the battery is used outside the recommended operating temperature, this may
result in reduced performance and operating time.
Page | 9