A simple way detect whether your battery is charged fully or not:
charge for 12 hs first: you will find the battery very hot because the charging process produce lots of heal
pull out the plug letting the battery's tempararure cool down for mimutes
pull on the plug again,wait for a few minutes ,touch the battery ,if become hot again , charge again,if not ,feel easy using your camera .
some other common tips about camera battery
Fully charge and discharge your new CANON BP-511 battery two to four times.
Charge the CANON BP-511 battery after it automatically powers off , then full charge the battery.
Charge CANON BP-511 when you're ready to use them after storage.
Never use an open flame near the CANON BP-511 battery or charger.