Rep Power: 0

Car's fine if used daily. Left unused for 1 day, dead as a doornail. Jump works but, rapid clicking sometimes happens and still starts off charger (electric). Battery and alternator tested fine. Can't figure out the problem.

 
Rep Power: 0

what did you use to test the battery? do you have an extra car battery lying around that you can use? i had a similar problem where i swapped in a old but larger battery that i charged with a charger. the car started fine that day but the next morning, all i get was a clicking sound from the starter, but would start fine with a jump start. i tested the battery with a dmm and it read close to 13v but the car still wouldn't start. i dropped in my original battery and no problems since.

btw, you posted this in the wrong section