Hi Tony, dont know if this is of any use but I use one with my Pentax, havent checked if there is a connector for the Canon. (can check tonight if you are interested)
Charge from mains, car or a 12v battery. Can supply 3V/5V/6V/7.4V not sure how long it would last drawing 7.4 but I just left it connected to a 7AH 12v battery.
http://www.interbatteries.com.au/pro...oducts_id/2836