I bought a Canon 60D about three years ago and I purchased two third party (DTI) batteries as back up.
Last year I bought a Canon 6D. The batteries are the same, LP-E6, so I didn’t get a spare battery as I had four batteries and two bodies. When I came to change the battery, I put in one of the third-party batteries and I got the error message that the camera “cannot communicate with battery”. Fortunately the genuine Canon battery was also free so I put it in and there was no error message and the battery was showing full in the LCD display. I supposed it was Canon’s way of getting you to use only their batteries.
Then about four weeks ago, One of the third-party batteries would no longer hold its charge I had to get a replacement, so remembering what happened with the 6D (and the fact that the original 60D Canon battery was still going strong) I bought a genuine Canon replacement. First of all it took a couple of tries before the battery would charge (the charger seems to work best if you plug the battery into the charger and then plug the charger into the mains).
When I needed to put the new battery into the camera I got the communication error message again. I took the battery out checked that it really was a Canon battery and put it back in and got the same message.
I had a good look through the Internet and the thing that worked for me was cleaning the terminals on the battery, cleaning the terminals on the charger (to make sure the battery charges correctly) and also cleaning the terminals inside the camera. To clean the terminals on the battery and the charger I used a wooden toothpick
and gently rubbed the terminals just to make sure they were clean, I didn’t use any solvents or anything abrasive (I also turned the charger upside-down and pressed down on the two springy terminals, C and T to the left of the rigid terminals + and -, to make sure nothing had fallen into the slots).
To clean the terminals inside the camera I used a hand blower (squeeze duster) which you would normally use to get the dust out of a camera body. I put the new battery in and it worked perfectly.
I came across advice about putting the camera in the freezer or short-circuiting the battery, personally I wouldn’t recommend either of these.
