Charge the battery initially for 9 hours. After the initial charge, under normal usage, your power pack should be fully charged in 3 to 6 hours. If the power pack is run-down completely, it may take up to 6 hours to become fully charged.
The red light is just a power indicator. The light will not go out, change color, or blink when the charging has been completed.
To prolong power pack life, avoid leaving the power pack on charge for extended periods of time (over 30 days without use). Although overcharging is not a safety concern, it can significantly reduce overall power pack life.