What year and model is your MBP? Is it the one in your signature? If you're not already doing so, use
iStat Pro (free) or
iStat Menus ($16) to get accurate readings of battery health and cycles and computer uptime, among many other things. A forum member has posted a copy of iStat Pro that has been "tweaked" to enhance compatibility with Mountain Lion. You can download it
here.
See the link for troubleshooting MagSafe adapters at the bottom of the CHARGING section of the following link. The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.