[One (M7) General] Magpir:
This guide is for unrooted devices. If u are rooted with a custom recovery , hard reset procedures may or may not apply .

Here are some tips of mine which have seemd to work for me

Edit : if u have just updated to ota , this tweaks will work better with hard reset .

Calibration technique: ( does not involve full drain cycle)

1) do a hard reset at 100% ( green LED) ,

2) when phone restarts charge till (green LEd) again,

3) Do another hard reset

4) fully charge to 100% (green LED)

5) drain the phone to 2% remaining

6) fully charge to 100%

1) Go to settings > network and change to WCDMA (only ) seems to make the battery drain lesser . May not work for some if coverage in yr area is spotty as it will drain more battery . But generally if u are in a country where there is good coverage and 3G everywhere, use this setting to save battery life .

2) Install this app WiFi-matic . Set the options there to what works best for u

3) go to settings - wifi -

"keep wifi always on"

and disable the

"best wifi performance"

setting . The HTC one wifi is extremely power efficient and for some it may give battery life savings more than the 3G radio sleep

4) use the in built HTC email for all your emails and avoid using separate apps for gmail and hotmail .

The Htc email behaves more intelligently due to smart sync feature

5) Turn on the settings - deepsleep , power saver at all times and u can individually customize the power saver options to your liking . The power saver still runs 4 cores but at a lower speed but puts connections to sleep . The difference between the 2.

Power saver - reduces brightness, cpu , vibrations and puts connections to sleep after 15 mins when screen off

Deep sleep mode - turns them off entirely after prolonged inactivity

6) go to settings > apps and disable any apps u are not using eg. stock HTC apps or other stuff like google now.

[Update]: Disable maps , turn off location all instances of location featurs in maps and phone settings"

7) the usual other stuff that are recommended with all phones like turn off bluetooth, gps , if u are not using them.

8) Blinkfeed - Set to update over wifi only ( edit: In the facebook app , set auto refresh interval to never for massive battery savings)

9,) disable or enable GPU rendering in settings. Helps saves battery life on quad core devices by using less of the Cpu cores . However this setting may work differently for some depending on the configuration set up eg, if power saving on /off. recommended is testing to see what works best for u. Edit : depending on your soc and phone variants, firmware . This setting either helps or does not .

10) New : go to settings backup and restore use HTC account instead of Google . Turn off daily backup .

12) New go to settings - autosync - Google , turn off all settings under "maps and latitude" and turn off "let Google maps access your location " in location settings . this steps may possible help some by minimizing the havoc Google maps does to battery life.

13) New : disable auto brightness in display and install lux auto brightness app from playstore, put values from as shown in the screenshot link for massive battery savings