I tried using 2 different after market batteries, one I don't even know the manufacturer, the other is a Wasabi . . . neither one of them are recognized and each gives me a different message when I power up:
Unknown - "Cannot communicate with battery, Use this battery?"
Wasabi - "Communication with Canon LP-E6/LP-E6N battery is irregular. Continue to use this battery?"
They power the camera if I choose to continue but I'm not sure how correct the battery percentages are. I'll stick with the original OEM Canon batteries just to be safe.