battery,phone,or normal?

[mark elmore]

Wirelessly posted (Omnia1: Opera/9.5 (Microsoft Windows; Windows CE; Opera Mobi/9.5; U; en) VZW:SCH-i910 PPC 240x400)

when my phone drops to 25% left on the battery it slows way down on everything. is this a normal behavior?
the phone part shuts off at 10% and wont make/ recieve calls(its just a pda),camera wont work and wifi shuts down at 15%. i dont mind the wifi but the phone part and slow down are annoying.
are these all normal and is there a work around?
i tried to kill the battery to recalibrate it to the phone occasionally but everything that consumes any major battery is off so when I go to bed its 5% and next morning still 5% , just a fancy brick until I charge it