Acer A501 - Manual (Page 9)

9 Charging your tablet
Using your tablet
Charging your tablet
For first-time use, you need to charge your tablet for four hours. After that you
can recharge the battery as needed.
Connect the DC-in jack to your tablet and plug the AC adapter into any AC
outlet.
Note: It is normal for the tablet surface to become warm during charging or
long periods of use.