It is always frustrating when you are attempting to take a picture and your camera's batteries die. If you are using a Canon camera you can charge the batteries (as long as the batteries are rechargeable) not only through a wall charger but through a USB connection charger. This allows you to charge your Canon batteries wherever a computer is located.
Remove the batteries from your Canon camera.
Insert the USB battery charger into a computer that is currently powered on. If the computer is off the charger isn't going to work.
Place the batteries into the charger. A light comes up stating the battery is charging.
Remove the batteries once the charge has finished. Insert the batteries back into the Canon camera and you are all set to go out and begin taking pictures again.