Originally Posted by fnd66
how do you get a better battery life.. its really bad
First of all, this is a really general question and also doesn't give us much information about what you have tried already and _how bad exactly_ it is. I shall nevertheless give it a try:
Maybe the battery needs to be recalibrated, which is a common issue after flashing a new ROM.
To do so, charge your phone to 100% without interruption, then unplug the charger and leave the phone running without recharging it until the battery is completely empty such that it turns itself off.
Repeat this procedure twice.
After that, battery statistics should again reflect your battery's full capacity.
If battery life is still bad after that, you should check under settings -> battery, if there is any particular process eating up all the power.
Also, if you want to temporarily increase your battery life above its usual level, say for outdoorsy activities, you can use an app like SetCPU to reduce the processor speed available. However, you need to be rooted to do that and the CPU settings need to be handled with care!
Apart from all this, turning off Bluetooth, NFC and WiFi whenever it isn't needed and reducing your screen's brightness can help extend your battery life. Also, if you are somewhere without any mobile signal reception, you will save heaps of capacity by entering flight mode, since the network search is quite energy intensive.
Sent from my Galaxy Nexus using xda app-developers app
Samsung Galaxy Nexus (maguro) / GT-I9250
Android Version: 4.3.1 Jelly Bean
Build: CM 10.2-maguro (nightly)
Kernel: Stock 3.0.72-cyanogenmod
Recovery: CWM 188.8.131.52