The Electronic Cigarette Pack charges one battery and holds four cartridges plus an extra battery. A total of two batteries and four cartridges can be held in this new pack!! To charge the Electronic Cigarette Pack, plug the pack into a USB port to charge the internal battery. The LED level indicator will show when the battery is fully charged. Allow 4-6 hours for the ECP to charge. To charge your Electronic Cigarette battery using the Electronic Cigarette Pack place the battery in the charging port. While you are screwing the ecig battery into the charging port press and hold the charging button the front of the pack. The LED on the ecig battery will blink 3 times indicating the battery is properly charging, the smaller LED light on the cigarette pack will blink numerous times indicated proper charging also. The indicator light will be red while the battery is charging and turn green when the battery is fully charged (when you press the button on the front of the pack, otherwise the lights will not be lit to preserve battery power). The ECP will charge up to four ecig batteries off a fully charged ECP pack.