For powerful image-making you need, well, power. Lithium Ion Batteries allow you to be certain that you won’t run out. Lithium Ion doesn’t require being fully run down to be recharged with peak performance. So no more guessing how close you are to the end of the battery, or worry about shortening the battery life by frequent recharges.

 A powerful battery is a must with digital cameras. And the Canon digital rebel requires a proprietary battery, so you cannot use AA batteries. Although expensive, the good news is you only need one spare, as these are so long lasting. And the replacement battery is cheap. You can order the replacement battery for your canon bp-511. It will also extend your run time. Now give you two referenced websites in US and UK, you can searh the battery that you need with better price:

http://www.camcorder-batteries.us/digital-camera-batteries/canon-bp-511.htm

http://www.my-battery.co.uk/digital-camera-batteries/canon-bp-511.htm