I’d like to share with you the policy I’m using to preserve my phone energy. I’ve tried most of the out-of-the-box policy, but I hated them all.
My personal policy is based on the idea that the components that require the biggest part of the power are the 3G and the display. So if you are able to keep both off you can have the best battery life. Having a smartphone and not using it and keeping it off-line would be – obviously – insane.
My policy is way more battery consuming than that, since I think I bought a phone to use it, and I use Whattsapp a lot, so I need 24/7 internet connection. How I solved? I power off WCDMA every time I don’t need to surf the web. In this way, I’m able to use Internet through the GSM (32kb/s) but it doesn’t eat my whole battery in a few hours.
I really suggest you to use the same policy since from my tests, it can increase your phone battery life from 8 to 36 hours without sacrificing anything.
As last thing, I’d like to propose to HTC to use this policy by default on their devices so their battery will last way longer than their opponents phones.
