soobiedoobie, it would be great if you posted this other website that had the functions posted about the workings of a battery..
like here:
https://www.autobatteries.com/en-us/...tarts-your-car
but FYI-
(kind of reader's digest)-
when key is turned, battery energizes starter momentarily to crank engine; then that's it.. an alternator then runs your vehicle's components,- AND charges back the battery; it basically keeps a fully charged battery, fully charged.. IF the alternator fails, this is when the battery's 'reserve capacity' kicks in, but seldom ever used..
just like the 'cold crank amps' .. most days (and most city/states) it is above 32degrees. but when it is minus 10, i would much rather have this batt:
https://www.walmart.com/ip/EverStart...E&gclsrc=aw.ds
than this one:
https://www.walmart.com/ip/EverStart...ze-34/28275671
same size.. same 12V.. different starting/charging characteristics..
i also do not think we ever said if your subie was a 4 or 6 cyl..? i do not recall..
but this could be why bigger battery tray; for a #34 as opposed to a #25; regardless here are some selections of same size batt. w/ different attributes:
https://www.autobatteries.com/en-us/...stalcode=80235
i hope this helps; but still, go to a service center;
or autozone, as they install free with purchase..