I have a 5DMIII with genuine Canon batteries and genuine battery grip. With the camera turned off, I found that two batteries (in the grip) last for about 10 days, maybe more but I never tested. Did ...
I couldn't resist and bought a bunch of Wasabi LP-E6 lithium batteries for my 5DMIII. They are much cheaper than Canon counterpart. Now, regardless of whether they keep the charge better or not than ...