why would a new battery go dead over night
www.youtube.com/watch?v=zdIKNnwEjIs -- check this out. It shows how to test for your problem circuit.
The first obvious thing to look at is if youre leaving something on. If not, then theres a drainage occurring through faulty wiring possibly. AAA checks these things for you or you could have electrical checked with YOUR mechanic. A stranger will take you through the ringer.
Looking for a Used Envoy in your area?
CarGurus has 1,961 nationwide Envoy listings starting at $2,200.
Search GMC Envoy Questions
GMC Envoy Experts