[Help] Want to CHANGE Battery Low/Battery Full Sound.

Hello Y'all

I had an idea a while back to change my Phones Battery Notification Sounds to Custom Sounds. I wanted to know if that is Possible on My Android OS and or Phone. Also what type of audio file needed.

Phone: HTC Desire HD

OS: Android Standard 2.3.3


Yes, it's possible.

MP3 / AMR / AAC / AAC+ / e-AAC+ / WMA / RA

can you expand?
there is no setting anywhere to change the battery notification, can you explain where this can be changed? I've looked under sounds and can't find anything that remotely resembles battery notification.