"killed" 12v for third time. Replace or recharge?

Leaving the rear hatch of a Subaru Outlook open for an extended period is a well-known way to kill the 12v battery. I have a dog that upon arriving home after an outing seems to believe that if he refuses to jump out of the open hatch, he may get another outing.

It was late, dark and I was tired upon arrival home after a long day's hike in the mountains. Went out this morning. Opps. Hatch open. Car tries to start. Nope. Sort of half turns over and gives up.

Hooked up my little GooLoo battery jump pack ($50 on Amazon) and starts right up. Leave it running for 30 minutes than shut it all down.

This is the third time I have done this since purchasing the Outback brand-new in March 2019. It is the original Subaru 12v. Car has 58K.

Got the hatch closed, will hook the battery up to my "traditional battery charger" in a bit, but thinking the smart move might be to replace the battery. Or, if it charges up, is all good??

 

The Outback (maybe all the subies) are known for this issue. IIRC, the car draws 15w from the battery, when the hatch is open. Has nothing to do with hatch lights (mine are off, btw). Apparently an open liftgate keeps the computer fully awake (or at least at a higher state of "awakeness"), and it uses that much power in that state.

There is a hack, if you put a carabiner through the hatch lock, that fools the car into thinking the hatch is closed. That's fine if I plan to leave the hatch open....but....

Charger has been on an hour and it started at about 90 percent and is now up to about 98 percent.Glad I have the little jump pack.

 

Lets see. Got answers from the A-group of folks I most trust. So....thinking I will play it cheap and leave the old battery installed. All the while making sure my jump pack is fully charged!

I am toying with buying the Harbor freight battery load tester, which I would link to -- but apparently their site is down -- but it's $20. That, paired with my Schmacher charger and my Klein tools multimeter, should make me good.

Funny thing about the HF tester is that it is on various sites, including Amazon, under various names for prices up to $50 -- and apparently PriusChat is not letting me link to those overpriced sites....so..off to clean the shed.

 

So got battery fully charged with my old school plug into the wall charger yesterday morning and went back up to the mountains yesterday afternoon. No problems with starting.

Returned home. Left the car running and opened the hatch and hauled the mutt out of the car. Closed hatch with car still running. Popped open hood, Shut down car. Returned some 14 hours later -- today -- and planned to go out with my meter and test the battery without opening anything other than the hood, which I had actually opened before shutting down the car last night.

But, groggy old habits die hard and I proceeded to walk up to the car and open the driver's door and at the same time said a bad word.....no, it wasn't Bisco.

Closed drivers door. Hooked up the Klein meter to the battery -- 12.7 volts. So good to go for now.
Will continue to keep the fully charged jump pack close and I encourage all of you that do not own one -- hey -- they are fairly reasonable and it is a lot better than trying to find someone to help you jump start your car -- if there is even anyone around -- which there usually is not in the mountain areas where I often drive.