With a full charge, the battery on your Pen and Tablet should last you up to 16 hours. Once the battery is fully drained, it will take 2 to 3 hours to fully charge. 

When charging the Pen Tablet, it is recommended that you connect it to your computer or USB hub that is connected to your computer. Using a USB charger that is connected to the wall socket is not recommended due to possible damage due to an incorrect voltage being sent to the Pen Tablet and causing damage to the unit.

You will want to charge your Pen Tablet once it gets to are below10% battery life.

Tool Tip: 

Once you are done with your tablet for the day, connect the USB cable and let the tablet charge overnight. It will then be fully charged and ready for use in the morning.