Testing with a multimeter i found that after charging (clutched her), the charge continually goes down. It went from 13.22v to 12.76 fast initially then tapering off more slowly. I assumed when a car was turned off whatever the figure was not under charge that the battery would gain power not lose it (a little bit anyway).

Am i wrong in assuming this?

Oh by the way shes starting fine now that i have charged the battery up and sanded the connections on the battery and earth body connection.