JVC BH-VC20EK Instructions Manual page 10

This charger is exclusively for use with JVC digital still cameras.
Never use in combination with other equipment.
Discharging
Batteries self-discharge while they are not in use. Be
sure to charge them regularly before use.
Operating temperature
Batteries are chemical products. Efficiency may
change for a time even within the recommended
temperature range, but this is not malfunction.
EN-10
Information regarding rechargeable batteries
Note:
New batteries or batteries that have not been used for a
long time (more than about one month) may not be
fully charged. This is not a malfunction, but is a
characteristic of the battery. Charge them two or three
times before using them for the first time or when they
have not been used for a long period.