2002 Chevy S-10 Battery Drain

This truck will drain enough power from the battery to cause starting problems at times. If it is driven a good portion of the day, there is little problem. However, it can be a charged battery and if it sits for a day or so, something is causing a power drain. The battery is a year old ( replaced an older battery thinking that was the problem ) but this was to no avail. I have checked what I can think of but ask for any advice / ideas before I make the trip into the shop for a search. Any advice appreciated ! Thanks.

Is this not a duplicate thread?