2020-2022 Outbacks use a Group 47, EFB type battery, and if you get a replacement battery, it must be EFB or AGM. The trick of driving with the headlights on is a bummer, but it works. Many of us have turned to periodic external charging to top up the battery that drains during the short trip.
At idle I can see voltages as low as 11.9 volts in my car, apparently because the alternator is shutting down to “save power” and the hvac fan, infotainment system and other electronics are just running on battery even though the engine is running. After shutdown, the battery will return to 12.3 volts or so, so that tells me yes the battery was under load when it read 11.9 volts.
When you get a new battery these days, they need to be charged with an external charger. Auto parts stores used to do this before selling you a battery and you had to wait for it to charge. Today, when you buy a battery, they just give it to you without checking the state of charge. The last NAPA battery I bought took 8 hours to charge at 4.7 amps before it was fully charged, and that was a small 30 amp hour battery for a Honda Fit, 151r.
People have bought aftermarket batteries after their OE battery failed while under warranty, fax the bill to Subaru of America and they get reimbursed. This is not a guarantee, but it seems to be common.
I think the best battery for a Gen 6 Outback is the ODP-AGM47 H5 L2 (47-650) ODYSSEY Performance Series Battery | ODYSSEY® battery
Your OE battery falls under your 3/36 bumper warranty.
One member claimed to have been told there is a fix to the charging system, but this is probably untrue as it could not be verified, but I too hope that at some point they will change the charging algorithm to better support short-haul drivers.
