I'm almost at my wits end with the battery in my m9. After charging to 100%, it holds a screen-on time of about an hour - give or take. I've tried solutions I can find through google: standard battery saving measures i.e. turning off location services and wifi, xposed and greenify, lower brightness etc... All to little avail as I was pretty battery conscious to begin with. I also tried/am re-trying battery recalibration because on of the most annoying aspects of this battery loss is the handset will consistantly die off at around 10-15% rather than drain down to 0%. I tried a variety of calibration apps and even tried manually deleting the batterystats file from the system.

I'm currently trying a recalibration app but noticed something odd. I drained the battery fully until the handset died then placed it on charge without turning it on (as instructed). When I plugged the charger in, the onscreen battery readout was 24%. I'm not really sure what that means... Is there still charge in the battery that isn't being used? Is the readout itself incorrect? If it is incorrect, what happens when it reaches 100%? Will it stop charging 24% shy of a full charge?

If anyone can please shed some light as to what is going on here, I'd really appreciate it. Thank you.