If you've gotten accustomed to seeing the remaining percentage displayed in the battery icon— in whatever style—on your rooted HTC EVO 4G while it was running Froyo, then you were likely disappointed when you flashed the rooted and deodexed Gingerbread OTA update (version 4.22.651.2) or various custom ROMs based on it and discovered that the modded icon didn't work anymore.
Some icons may still work on the latest build but rather than waste time playing a game of trial-and-error, you can just flash Evolutionmod's 1% increment charging/usage battery icon mod (tutorial here), wipe your Dalvik cache (in recovery mode: advanced > Wipe Dalvik Cache), reboot, and enjoy the rest of your day with a fresh new icon in your status bar.
This mod has been confirmed to work on the rooted, deodexed OTA update, which is what I'm running on my EVO, and a few other mostly stock ROMs based on it. Compatibility with other ROMs is not guaranteed.[xda-developers]