From my experience, i have tested many 3rd party batteries on many cameras from the BP-511's to the latest 7D,5d3 batteries and most 3rd party batteries, while good for the first or second cycle, tend to lose memory quickly and it's charge capabilities are severely diminished. Some of the 3rd party BP-511's i tested on a full charge, after a few charge cycles only could support 50 or so photos with occasional chimping... The newer batteries were not as bad, but still i have not found batteries that hold a charge better than the OEM's so I have resigned myself to stick with OEM's... It does not surprise me a bit that canon made their changes to help discourage 3rd party batteries. Not saying what they did was right, but it's practical.