External Battery (sold separately)
Connect the external battery to ND2901 (marked "BAT") to extend the operation time to about 90 minutes. Use the internal and external battery together and increase the operation time up to 3 hours. To charge the external battery, connect the external battery to "BAT" on the ND2901 and charge it with AC Power Adapter (or a USB cable). It takes about 7 hours to charge both internal and external battery (sold separately) when the ND2901 is not in use.
Connect this external battery to [BAT] connector to use SSD as an internal storage.