Paid close attention yesterday at a wildlife sanctuary. Fresh battery, 1 hour and 40 minutes of handheld, mostly Mode 2 IS (which was a mistake, I see!), one card only, a ProGrade 128GB CFE. Near the end, maybe after 1 hour and 20 minutes, I heard the ECFS sound change, get clunkier, a bit louder. Checked my battery and I was down to 54%. When I left I was at 48%.
How many shots? 1012! Quite a few bursts, mostly birds-in-flight, but also some on the ground or wading.
I think my battery usage is more related to how long I'm using the camera more than how many shots. So if I only take bursts of 2-3 shots, maybe 4-5, during a 90 minute hike, I get about 400 shots before being down to 50-60%. (Sorry, AlanF, for using such imprecise language as "several hundred," but I haven't paid much attention to the usage. I did buy two extra Canon batteries after a week with the R5.)
Does CFE use significantly more power than SD?
Oh--I have my Sensor Cleaning set to manual only, and I engage it only after changing a lens.
I can put a new battery in, 100%, do a sensor cleaning, a format, a few things in the menu. And, whoa, suddenly I'm down to 94%? Strange.
One other thing, I am seeing that the newest batteries drain faster just sitting in a drawer. (And this makes me think back to the days of the 5DIII, how I could go two months without using it, having left the power switch on, and I'd still have well over 80% battery charge. The 5DIV was never like that. On or off when stowed, batteries drained in it steadily.)
As for testing, I'm not seeing any real inconvenience or unexpected behavior. I keep an extra battery in a little pouch in my pocket. I charge as soon as home...So I don't want to put in the time or wear and tear on the R5 for a test. And I am too busy to try to figure out how to set something controlled using an Android phone to just fire away...
I did map the Movie Record button to switch between EVF and Display, but I only use that when walking for exrecise/pleasure with a smaller lens, and the rig is slung over my shoulder so that the EVF gets constantly activated by my shirt. Carrying the 100-500mm in my hand by my side doesn't cause this.
I do believe that with IS on all the time when the body is active, it makes sense that we'd see a range of drainage patterns here. But where is the "in spec" threshold? I'll leave that to others for now!
Good luck, AlanF! I do wonder if a particular battery could be part of the equation--even if it is showing as normal?