Battery Warning plugin is a PSP plugin that shows a message on screen when your battery reaches 15% or less charge. Works in VSH/GAME + Homebrew Games & Apps.

Why bother when the PSP LED blinks when the battery is low? Well lets face it, who can honestly say when they are stuck into a game that they even notice the LED blinking at all, also added to that, the fact that when your playing a game your thumb practically covers the whole light, it’s not an ideal method of warning.

http://forums.qj.net/psp-development-forum/164138-release-battery-warning-plugin-v0-3-a.html