I have a C-15 Drill that I purchased 11/13. One battery shows a full block of charged lights after being charged while the second battery only shows 1 light after a full charge. Is there something wrong with the second battery? The power seems to be Ok for a while, but runs out quicker than the 1st battery. The 1st battery hasn't been charged in about 2 months and still holds the full block of lights, while I have charged the second battery a couple of times in the same period and it just shows that one light.