Subaru Outback 2017 battery
Battery died in the Subaru Outback. Bad
battery was just replaced with a new one a
few months ago (Feb) and now it is dead
again with no reason. Suspect it is something
more than just the battery. It took the dealer
10 days to diagnose and replace the battery
the first time. Now I can’t even schedule a
service appt for almost 1 month. What else
could be causing problem, if it isn’t just a
defective battery? Do I have to wait for a
month and go to dealer to have warranty
A defective alternator will deplete a battery in much less time than that. I suspect a parasitic drain. There's something in the electrical system that's causing electricity to flow when the car is off; could be a switch stuck closed or an electrical short. As the problem wasn't fixed on your last visit to the dealer, don't wait. The mechanic just has to check the car one electrical system (fuse) at a time to find out where the problem is, then track down the culprit. A good mechanic shouldn't take more than a few hours to do this. Meanwhile, have them authorize a rental for you.
This is a common problem with newer Subaru's due to the inadequate battery Subaru installs. You may get a new one under warranty but my suggestion is to get a high capacity battery such as Optima.