2002 Pontiac Montana electrical

Took car to advance auto, tested starting/battery etc system. Found can has a drain on the battery. Went thru fuses looking for drop in amps. Found the ctsy lamp had a drop from 4.45 to, 85 checked the doom lights and found they appeared to be burnt at the socket (very hot) took out bulbs. Put a charger on the battery to ensure a good charge. In doing so the charger would flux between charged and 50 every few seconds, feel some other issue is the problem and not sure how to proceed.