While the stock battery icon that permanently resides in the status bar of your HTC EVO 4G is a fine way to monitor your remaining power, it isn't as accurate or informative as being able to see the actual percentage, overall health, current temperature, and voltage readout of the battery.
That's why you might want to try Battery Indicator, a handy little percentage icon that sits on the left side of the status bar, with more details (shown above) accessible through the pull-down notification area.
Here's how you can use it to keep an eye on your EVO's battery:
1. Download and install Battery Indicator by Darshan Computing from Android Market. There's a free version, a $0.99 pro version exclusively for the Motorola Droid, and a $0.99 pro version for everyone else. The pro version includes some extras like high-resolution images, color options, and boot-up behavior settings, but all the main features are included in the free version.
2. On the EVO, press the program menu button and tap Battery Indicator from the list that appears.
3. Tap "Hide This Window" when you're ready to start using Battery Indicator.
4. Now just glance at your status bar whenever you want to check your battery. Pull down the notification bar to see more information.
There are similar apps available in Android Market (some include a widget that you can use on your home screen), but I like Battery Indicator best because it's unobtrusive, informative, and easy to read.
According to Darshan Computing, "It doesn't do any polling. It receives a broadcast message from the OS when the battery status changes, then it simply updates the icon and goes back to sleep. What this means is that it will take up a small amount of RAM, but essentially 0 CPU cycles, so it can't drain your battery."
The only downside to this and other battery utilities is that they won't replace the stock battery icon. But if you can live with having two battery icons in your status bar, then I think it's a great thing to have on your HTC EVO.