I happened to see this FAQ when browsing the official Hanlin website, hope it helps:
4. How long the battery last after charging? Does the battery can be replaced by the user?
A:It can support the power for turning not less than 8000 pages; music playing for up to 10 hours after fully charged.
The product adopts the
general battery (Nokia Bl4c, Bl5c); user can buy it in any electronics shop. Battery fully charged need three (3) hours through charger, and six (6) hours through USB cable
Original webpage is
here.