Have a 2016 Outback 3.6 and
Have a 2016 Outback 3.6 and had several episodes of battery draining as the car did not start -during a 15 month period -(Jan 2019 thru March 2020) and had to replace battery twice. AAA told me there was a battery drain coming from somewhere.The dealer tested the car each time and found nothing wrong with the alternator and rest of the entire electrical system —which was extremely frustrating. However in September of 2020, after battery failed again—the dealer once again tested the electrical system and determined that a faulty telematics unit (the size of small TV cable box) inside the dashboard was causing a battery drain. A new unit was ordered from Indiana and I had wait a week for delivery. The dealer gave me a new loaner car till the replacement part arrived. Since the part replacement, my Outback has started with no problem—during the snowy winter of 2020/21 and even when the car wasn’t used for 2 or 3 days.
Bottom line, I was lucky with having a good Subaru technician to determine the cause of my vehicle’s battery drain. I was told that a defective telematics unit is not a common issue. But since that replacement (about 9 months ago), the car is running fine and most important- there are quick and reliable startups. Just hope it stays that way