Canon BJ-10sx - Manual (Page 89)

Charging the Battery Pack
3. Hold the printer with one hand and the battery pack with the
other hand. Make sure the writing on the battery is up and the
terminals are down. The terminal end of the battery has silver
arrow showing the direction in which you insert the battery.
4. Insert the battery pack in to the compartment -- terminal end first.
(When installed correctly, the writing on the battery pack is
upside-down if you're facing the back of the printer.)
5. Replace the battery compartment cover.
6. Rotate the printer stand back to its original position.
NOTE: Always charge a new battery pack. A new battery is not
charged.
It takes approximately 10 hours to charge a new battery or a fully
discharged battery. When you are charging a battery pack, the
printer cannot print.