NEC C944 - Manual (Page 11)

9
Battery
Capacity Icon
When batteries are replaced, no icon will be displayed before a
complete charge cycle has been completed, except when
almost empty batteries are inserted in the phone, then the icon
will be shown immediately.
When the battery capacity icon is displayed the indication is
reliable.
If charged batteries are inserted, the batteries can become hot
during the first charge cycle, and if the fully charged batteries
are removed from the phone and inserted again, the batteries
can become overcharged.
Charge
Warning
When the batteries’ capacity is almost exhausted, an acoustic
warning is given in the form of 3 short ”beep” signals (only dur-
ing a call). Approximately 5 minutes of talk time is left.