My new Canon 90D is powered by LP-E6N battery. Dimensions are the same as LP-E6 batteries, just the mAh is little higher. Experts opined that both these batteries can be used interchangeably. So, I decided to put this to test. LP-E6 packs 1800mAh and LP-E6N features1865mAh.
I found a fully charged LP-E6 battery does run the 90D properly. However, the same battery with around 50% or less remaining charge does not. I inserted one LP-E6 battery with 53% remaining charge into 90D and it said – change the battery pack. I tried twice and ended up with same result.
The same battery with 53% remaining charge is running my 7D in full power (continuous shooting, rapid bursts etc). Unsure whether the slight difference in mAh is creating this discrepancy!
Would like to learn more about it!
Thanks in advance.
Total battery capacity is just part of the specification picture, another aspect is how much current it can produce under load and with how much voltage drop. Your 90D is likely basing the "change battery" recommendation on the voltage delta between no load and loaded.
This same issue shows up in other ways. My first Canon 1 series was a 1D Mark II and at one point I needed replacement battery packs in a hurry before heading on a trip. B&H and Adorama were both back order status on Canon so I tried a third party brand. It seemed to charge and work normally UNTIL I shot a few fast bursts with the 1D M2 and I noticed the battery level indicator would drop from full to 1/4 during the burst and if I didn't immediately interrupt the burst then the camera would lock up requiring battery removal to reset. After a burst, the indicator would return to indicate a fully charged pack. The third party pack just couldn't sustain the 1 series burst current demand causing voltage to sag under that load.