[EVO 4G Q&A, Help & Troubleshooting] ikkysleepy:
Nah, it works. You just have to know what you are doing. What's using the battery life? What's the condition of the battery? What is running and what apps drains the battery? Here is an outline to Tame Your EVO:

0.) Load Balance your battery

Just charge it till the light turns green, unplug, charge till green, turn-off phone & charge till green, unplug and charge till green 7 more times or so.

1.) Auto Kill Apps

I have the paid version of Process Manager and ignored things like Facebook and HTC/android tasks; every hour everything gets killed that is not in the ignored list. If you don't know what to kill then trial and error.

Apps Running Before

Crap that came with the phone

Crap I downloaded and forgot

Crap you don't use

2.) Kill Startup Apps & Services

A lot of startup apps and services are running in the bg, so use something like Autorun Killer or a Task killer to disable them from starting up or kill them when they do. I disabled apps like Flickr/Sprint Tv/etc. and services I don't use like GoogleTalk.

Apps that start on bootup

Android Service (good)

Google Talk Service (bad)

SetCPU (good)

Etc.

3.) Tweak Sync Setting or Disable Sync

I have my settings set to only sync gmail, weather and 2 e-mail accounts every 4 hours or so.

Apps Running in the Background on Sync

Weather for City 1 (once a day)

Google Calendar (Never)

Google Mail (every 4 hours)

Google Contacts (Never)

Stocks (# of stocks) (Never)

Mail (# of accounts) (every 4 hours reg. and every 4 hours peek)

4.) Setup CPU

Create a profile that you can live with. I have my EVO underclocked and set such that when the battery drops the cpu also throttles down; the most important thing is setting the speed to the min when the screen is off.

5.) Other Tweaks

I have my battery widget and Facebook and made sure to clear all my sense UI. I use ADW but have my sense still running, I think, so I set the sense to a clean state and then switched to ADW. I Don't use live wallpaper and have a colorful bg. Here are some tips users posted before:

Disable "enable always-on mobile data"

Check that you are on the CDMA (Auto)

Don't use Live Wallpaper

Don't use cpu or data intensive widgets like news and weather that update hourly

Consider using something like locale or Setting Profile to auto change your settings based on a condition.

Monitor your battery and memory. Some apps take a lot of memory but don't use up a lot of battery unless you are using them. Some apps take up little memory but are cpu hogs. After a while you know which apps are hogs and know when to use them; for instance I try to use XDA/NYTimes app when I am on WIFI at home/work b/c while I am on the train it will just drain my battery.

At this point you should be getting great battery life, if you are not then consider this: location, location and location. If you are located in a bad sprint coverage your battery will drain much faster. If you are located were it is HOT your battery will drain FASTER. I know when I ride BART (train) my battery and signal goes from say 90% to 70% in 25 minutes just surfing the web, but that's because the signal is weak and goes in/out. When the battery gets hot, there goes your battery, so how you hold it might make a slight difference in terms of the battery temperature, but YMMV.

I hear a lot of people complain about their battery, but if you are in a good coverage area with average temperature and you did the load balance of your battery, tweaked your start up apps, have auto kill turned on and sync tweaked out and you still are not getting 14+ hours then something might be wrong with your battery. Your battery is stored energy,and you are using that up somehow. What is that something? It could be a stupid app causing android not to go to hibernate, like someone said, or it could be that AOL messenger downloading ads and you don't even know it. Tame your EVO!

You can get even better battery life if you use a custom ROM with modified kernel and radios, but you know these are the basics.