Macbook Pro taking 20 hours to charge but charges faster when it is " not charging"

Hi guys, I have an extremely werid problem. So since August of last year my 15in mid 2010 Macbook Pro began to take 20 hours for a full charge. I made an thread back then and details of my problems can be found at https://discussions.apple.com/thread/3280834?start=0&tstart=0

So I took my MBP to the Apple Store, the guy there said I might need a new motherboard. Since I didn't want to pay the $400 for it. I decided to make my MBP a desktop by hooking up a 24in monitor to it with keyboard/mouse and take it out once in a while. The other day I was in the library and my battery ran out so I plugged in my charger. The light on it stayed green the whole time and I see the message "not charging" near the battery icon. I did take notice of it but when I unplugged my charger about 1.5 hours later. My battery was full at 100% I was pretty much dumbstruck. So to reiterate

Charger Light Green- message = "not charging" - take about 1.5 hours to charge from 0 to 100%

Charger Light Red - message = "20:00" - takes about 20 hours to charge from 0 to 100%

And I can't seem predict when the "not charging" charging happens. It happened one more time to me and rest of the time, I get the red light and 20 hr full charge. In both occasions, my battery was completely out and when I turned mac back on with the charger plugged in (green light), it restarted instead of resuming and I get the message that my "clock is set before Jan 1st 2000" (date might be wrong) and had to re enter my wifi info. Seems like something had been reseted on the mac.

This makes no sense at all, can someone explain to me what is going on?