I would try resetting the SMC first here. Follow this Apple TN: [http://support.apple.com/kb/HT3964|Intel-based Macs: Resetting the System Management Controller (SMC)].
Also, check out this little gem [http://www.coconut-flavour.com/coconutbattery/|coconutBattery 2.8]. Lets see what it tells us on your battery and the charging circuit.
I don't think your DC in board is any issue here. I would make an effort to clean the contacts of both the charger and the system if the contacts look dirty.