Motorola E815 / E816 Hollywood

Today is the first day that I have really pushed this phone by listening to MP3's continuously. It plays only about 3 songs about 4-5 minutes each on a fully-charged standard battery before it starts displaying the "low battery message" and the battery indicator is red. If I power off the phone and turn it back on then it shows green on the battery indicator and the battery level display shows 6.

I'm assuming the extended battery fits under the cover and doesn't increase the thickness of the phone (is that correct)?

Thanks!