TimeBatteryPercent is a plugin for PSP. It allows you to show the percentage amout of available battery energy left, directly next to the battery icon.

Changes:

*Added compatibilities with 5.00, 5.02, 5.03 and 5.50 cfw (for 5.02 and 5.03 I didn’t check if it works but it must be ok)
*Added configuration file (TimeBatteryPercent_config.ini): you can configure TimeBatterPercent like you want. Indeed tou are now able to:
-show or not: hour, minute, year, month, day, battery time left (in parentheses), battery percentage, cpu/bus clock frequency
-choose date format (YYYY/MM/DD or MM/DD/YYYY or DD/MM/YYYY)
-choose hour format (12 hour or 24 hour clock format)
-choose to display string date format (like November 24 Thursday for example) or not (like 24/11)
-write what you want under clock and date information (if you want to write something go to the configuration file and in front of “writrewhatyouwant”
write what you want :p else you can write nothing if you want

http://forums.qj.net/psp-development-forum/161613-release-timebatterypercent-version-2-0-a.html