Battery draining overnight

Battery is drained in the morning after being fine while driving during previous day. Boost vehicle in morning and works fine all day but is not sitting for long periods. Did some testing on battery and voltage is good, battery is charging and removed negative cable on battery to test all fuses and relays to see where power was being draw from but found nothing. Battery is draining overnight because it seems as though something is draining power from it other then the computer. What could be doing this? Has the alternator grounded internally and how do l test it or is it possible that l have a bad or stuck relay?