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

Discussion in 'Fred's House of Pancakes' started by Stevewoods, Aug 31, 2022.

  1. Stevewoods

    Stevewoods Senior Member

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    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??
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Check it with one of the electronic load testers. You can buy a pro-sumer level tester for $50~80, and a lot of automotive retailers will have similar pro-level testers on hand, will test for free.

    To use these you need to hook up directly to the battery posts, enter a couple of parameters (battery type and rated CCA). Then run the test, and it'll display the as-tested CCA and give a verdict. With mine the verdicts are "pass", "pass but recharge" and "fail".

    The model I'm using is Solar BA5, but it's been superseded; think this is the replacement (doesn't say BA anything):



    Clicking on the link, you'll see the alternatives as well, lots of brands to consider.

    that said: 3 strikes IS getting up there.
     
    #2 Mendel Leisk, Aug 31, 2022
    Last edited: Aug 31, 2022
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  3. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    Is there a trunk light that can be turned off? My Rav4 has one and after leaving the hatch open once, I turned my light off (as I can always turn it back on) and now can leave the hatch open. In The RAv4 the dome light in the passenger compartment is a separate item that turns off when the car door is closed so if I open the hatch, only the trunk light would go on and now it doesn't. Left open over night and no problem.
     
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  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Even if no lights are lit, I think having any doors (or the hatch) open "wakes up" the car, increases the phantom drain.
     
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  5. Stevewoods

    Stevewoods Senior Member

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    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.
     
  6. Trollbait

    Trollbait It's a D&D thing

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    Left my 2022's hatch open for a bit while unloading stuff. After about 15 minutes, the hatch wouldn't close by pushing its lock button. Guess Subaru has the car go asleep after a time now.
     
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  7. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    See if you can find and defeat the nanny switch for the rear hatch.
    As far as the battery is concerned if it takes a charge and you trust your jumppack I'd call it good.

    If and when the battery fails to start the car when you did not leave the pod bay doors open then you can replace the battery.

    Good Luck!
     
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  8. Stevewoods

    Stevewoods Senior Member

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    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.
     
    #8 Stevewoods, Aug 31, 2022
    Last edited: Aug 31, 2022
  9. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    Klein makes good stuff.
    As cheap as my beloved company famously is, they spring for Klein tools without having to stick a crowbar in their wallet.
    Remember that you're only testing the battery under a partial load with a multimeter - even with the hatch open.... :p

    I've managed to survive for decades without using a load tester and we have BIG lead acid batteries at big bell!!
    Perhaps I'm biased because of the 'free' ones that they have at places that sell new batteries. ;)
     
  10. bisco

    bisco cookie crumbler

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    assuming it's not a prius battery, you should be fine
     
  11. Stevewoods

    Stevewoods Senior Member

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    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.
     
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