I'm not sure if this qualifies as badassity, but I thought this might benefit others.
Poor battery life is a common critique of smartphones in online phone reviews and forums. This post explains one reason for this, and a workaround to extend battery life.
I bought a used HTC Sensation in December 2012 after avoiding cell phones for as long as possible. The phone was officially released May 2011, but is still a well-spec'd device in 1Q13. I had done plenty of research prior to picking this phone, and picked up on the poor battery life theme. So I had low expectations, and sadly those expectations were met.
To clarify: I expected the phone to consume battery during actual use, but I was not prepared for high battery consumption when the phone sat idle. In my ignorance, I initially assumed this was due to the age of the phone & battery. I received a new battery for Christmas, but the idle drain persisted.
WiFi calling is a feature of T-Mobile and Republic Wireless (maybe others). In my case, I have poor T-Mobile reception inside my house so WiFi calling is great. Other carriers offer similar functionality through use of their femto cells.
I have WiFi at home and work, and my phone will automatically disable its cellular radios when connected to WiFi. The behavior is like this:
1) get within known WiFi AP,
2) associate with WiFi network,
3) disable cellular radio.
This works automatically at home and at work, which is nice. Except that I noticed a pattern of drastically different battery consumption rates at the two locations. Looking at Android's own battery power info (Settings -> Power) as well as Battery Battery Stats, I noticed that my main battery drain at work was WiFi. I'd lose 60% battery in a 9-hour shift. With this knowledge, I disabled WiFi at work - leaving just the cellular radios on. This has cured my at-work idle battery drain!
The cause turns out to be related to the distance between my phone and our wireless access point. At home, I'm never more than 20 feet from my AP. At work, my desk is 50 feet from the AP, through two cinder block walls and two metal stud framed walls. At home, I have a "loud" WiFi signal. At work, my phone struggles to "hear" our access point and frequently drops & reacquires its connection.
This applies to any device that automatically associates with known wireless networks - if your signal sucks, it'll drain your battery quick.
I now manually enable WiFi at home and disable it at work. I'm going on over 3 days since my last charge, and I still have 25% life remaining - image attached.
Based on my reading, there are two explanations for this.
1) It takes a lot of power to "hunt" for a RF base station. This is as true for WiFi as it is for cellular base stations. Here's an interesting look at
how WiFi affects laptop battery life. In short, while using WiFi resulted in only a 2% decrease in battery life, constantly dropping & reconnecting to an AP caused a 6-7% drain.
2) The inverse square law applies to all RF wireless transmission through clear airspace - radio signals attenuate with the square of distance. Add obstacles and other losses, and attenuation increases. The RF amplifiers in
cell phones compensate for this by automatically adjusting output power depending on distance and signal quality. If distances are great and/or signal quality is poor, output power will increase.