XPS M1530 power issues

I have an XPS M1530 that charges my batteries intermittently.  I currently have a fully charged 6-cell battery (that took about 6 hours to eventually charge 4%) and a 9-cell that is sitting at 7% charged.  I had this problem before (about 2 years ago) and Dell switched out the motherboard.   That fixed the problem for about 3 months.  What is currently happening is that I have constant power from the AC adapter.  However, I have a "Plugged in, not charging" status alert.  Also, if I unplug the AC adapter, wait for the green LED to turn off on it, then plug it back into the wall, the installed battery will charge for about 30 secs, stop charging for about 2 mins, start charging again for about 30 secs to a min then stop charging again.  With my 6 cell battery, it ran through this cycle enough times to finally charge the battery from 96% to 100%.  However, when I swapped over to the 9-cell that was sitting at 5% charge (due to an overnight power outage) I have only been able to get it to charge an additional 2% over the past 3 weeks.  Any ideas on whether or not this is a motherboard issue or an AC adapter?  All my connections are snug and constant and can run the laptop on AC power even with batteries removed.