When charging the Phantom's batteries I'm used to seeing the green LED's light up progressively as the charge nears full - so at first there is one solid LED and then two and the other LED's flash until they are solid and then they all go off and the battery is charged. Today I decided to top up both of my batteries which were around 50% fully charged. On connecting them to the charger all the LED's flashed in cycle as if the battery was empty and after about 40 minutes all the LED's went off. I disconnected the battery and pressed the button on the battery and all four LED's are solid showing that the battery is fully charged whereas before it was showing only 2 LED's. So the charger and battery are definitely charging OK but I'm puzzled as to why the LED's didn't progressively go solid as the battery charged up? Could it be because they were already at 50% although I'm sure I haven't seen this behaviour before?