Thanks for the helpful answers! I unplugged the neg terminal which stopped the beeping. After 24 hours on the 12 amp charger, it still wouldn’t turn on — not even the interior lights. Called Subaru Roadside Assistance, they got here in about 75 minutes and were able to do it with a more powerful jump starter. I checked to see if the interior lights were on — none. Then took it to the dealership without an appointment where., to their credit, they took it right away and called me back after about 90 minutes saying the battery had a 20% charge state but was otherwise fine. The service advisor said that the car could not be expected to start if it sat for more than 2 weeks without a trickle charger. I said bull!, it has lasted more than that many times with no problems They are going to do a parasite drain test but at this point I still think batt is possible the fact that it wouldn’t charge on my 12 amp charger.
Yes, I read the last 6 pages of the Gen 6 Battery Powerthread 
Do I have unrealistic expectations about charging the battery enough to start after 24 hours on a 12 amp charger?
Checked for replacement batteries within 10 miles of N Seattle (AutoZone, Napa, Walmart), almost all cost around $250, not many options available. Autozone has an EFB for $239 with 110 minutes of backup, the AMG for $249, with 100 minutes; both have a 3-year warranty. Local Subaru dealers now only stock 1 replacement battery for all Outbacks (and Ascents): the SOA821B900 has higher capacity but is also slightly larger in dimensions. When replacing an original fitted battery (SOA821B700) with the new SOA821B900 EFB, additional parts and slight modifications will be required to ensure proper positioning and secure retention. Cost is about $380 with extra parts; I don’t know what the warranty is.
If I’m forced to buy a new battery on my own dime, which one is likely to be better for a car that sits in the garage more than it’s driven?
