I got my Outback 8/27/21 and have less than 6000 miles on it. I drive it 5-6 days/week. A few months ago was unable to unlock to drive to work, battery dead, assumption was “must have left something turned on”, battery charger got it going again in a few hours. This week while on vacation, went for a short hike and came back to a dead car. No nearby dealership so $350. later had new battery from O’Reilly’s which was not a subaru and several dash lights on that could not be reset or turned off by the guy @ the auto parts store. Currently at local dealership where we were told would have to pay for 2nd new battery in 48hrs as the off brand does not allow for diagnosis of all the electronic failures (check engine, brake, no cruise control, eyesight off, RAB off) unless there is a subaru battery in car. Warranty won’t cover new battery because we did not bring back the original that failed while we were stranded. Is this Subaru battery just a piece of junk? Why & how does is drain so quickly?
On either of my two older cars, as long as the battery fits the allowable space, posts are in correct position, it will do the job w/no complaints. But some newer cars these days do require a very specific battery, partly b/c the car’s computer software now controls the charging algorithm, and for that to work correctly requires specific battery functionality. In my two older cars the charging strategy is determined by a simple voltage regulator, no computer involvement. Newer cars have more demands for electrical power than my two cars, what w/all the electric gadgets and gizmos, power windows, window defoggers, heated seats, electric steering, entertainment systems, cameras, security systems, & the like.
That said, seems unlikely the Subaru battery is the problem. First step for w/batteries that run out of juice for no apparent reason, ask shop to measure the battery voltage before first start of the day, after car has been unused overnight. Should be about 12.6 volts. Then immediately after starting engine, 13.5-15.5 volts. You are welcome to report the numbers measured for your car, might get some more ideas.
It seems to be a problem with past vehicles too. check to see if there is a software update for your vehicle. the article shows there is one for the other vehicles listed.