There's already a bunch of "battery savers" that cannot really save your battery life - they rather drain your battery and pretend that are very useful and keep running and drain your battery. Well, there are still some apps that really can save your battery - the app called One Power Guard can definitely save your battery and moreover, it will decrease your charging time and speed up your Android phone!
One Power Guard, as the author says, is a unique battery enhancement tool designed to conserve your battery power an increase uptime on rooted Android smartphones/tablets. One Power Guard will decrease your charging time and increase your device performance while also increasing your uptime.
So, what the app really can do?
1. Extends stand-by time and battery life; optimizes charging parameters
2. Optimizes system kernel and CPU usage to improve device performance
3. Six (6) customized power-saving modes to suit different scenarios
4. Proactively guards from power-killer apps and safely shuts down useless power-consuming programs
5. Fast ON/OFF settings for 100% system customization
6. Intelligently switches to/from WiFi/Cell data to preserve battery life
7. Professional Tips on power optimization
And yes, it requires root to work.
The app really seems to be working, also due to high amount of satisfied customers:
"I started in the evening, with fully charged battery, at 22.00. I checked battery status (%) next morning at 08.00 - without One Power Guard 2.2: 78% - with One Power Guard 2.2: 97% No need to say more... One Power Guard 2.2, at least for my phone, is working"
"I found the second solution, which is using the ONE POWER GUARD. Now, the battery life IMPROVES EVEN MORE! Now when I wake up to check my device, a whole night sleep is just draining 2-3% the most!"
More user's stories can be found HERE.