The battery is good, but sometimes it won't start, the relay is clicking but won't go through to the starter solenoid. One thing I do to solve is to unplug the solenoid for 15 minutes then reconnect afterwards so it'll start. This isn't a permanent solution. What is the probable cause for this problem?

I also noticed that when the car is parked for a few days, the battery gets drained. When I disconnected the solenoid connection for a month the battery is still good. I'm assuming that the first problem is related to this one as well.