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2018 Prius, second 12V battery just died. What's going on?

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by Halcykon, Apr 12, 2020.

  1. Halcykon

    Halcykon Junior Member

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    I'm not sure if I just happened to get two defective batteries, but both times, my 12V battery died after a two week period of no driving.

    The first time I was overseas for two weeks and came back to a completely dead 12V. That battery was about a year old. The dealership replaced it with another 12V.

    The new battery just died today. 6 months old. I drove 55 miles two weeks ago, and didn't drive it for the past two weeks.

    What's going on?

    • Am I just unlucky and was given two defective batteries?
    • How would I check if my car is drawing more power than normal? I turn everything off. Maybe the USB cables I leave in the car is drawing power? (unlikely)
    • I'm thinking about getting a trickle charger or small automatic tender type 12 V battery charger. Any thoughts on those?

    I'm at a loss here, and I'm concerned that this is going to be an ongoing problem for my car...
     
    #1 Halcykon, Apr 12, 2020
  2. Raytheeagle

    Raytheeagle Senior Member

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    Welcome to Prius Chat(y).

    Some questions:
    • Where did you buy the battery at?
    • Any after market accessories on your Prius?
    • Any warranty from the store you bought the battery at?
    • How frequently are you turning your car on and how long do you let it run for?
    Good luck and keep us posted(y).
     
    #2 Raytheeagle, Apr 13, 2020
  3. alanclarkeau

    alanclarkeau Senior Member

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    You said "I drove 55 miles two weeks ago" - how long before that was it that you drove? I've heard of a few batteries in various cars which have gone flat due to COVID-19-lockdown.
     
    #3 alanclarkeau, Apr 13, 2020
    amos likes this.
  4. FuelMiser

    FuelMiser Senior Member

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    "Defective" can only be determined by putting the battery on an analyzer found at battery shops. Surprising that a new-ish battery cannot be reconditioned, again by a battery shop. Dealerships are in the business of selling replacement parts, not reconditioning existing ones. I would definitely buy a trickle charger in your case when you're not driving the car much.
     
    #4 FuelMiser, Apr 14, 2020
  5. bisco

    bisco cookie crumbler

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    check the load when it's off. you can shut off sks while away
     
    #5 bisco, Apr 14, 2020
  6. alanclarkeau

    alanclarkeau Senior Member

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    I wonder if there might be something else drawing current. I assume you don't have a DashCam or similar which runs 24hrs/day?

    There was talk a couple of years ago about someone who bought a PRIUS and it had some monitoring/security gadget installed by the dealer for while it's sitting in the Dealer's yard - which they'd forgotten to remove.
     
    #6 alanclarkeau, Apr 14, 2020
  7. Halcykon

    Halcykon Junior Member

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    How do I check the load when it's off? And is there a way to turn off the sks without going to the dealership to do it?
     
    #7 Halcykon, Apr 14, 2020
  8. Halcykon

    Halcykon Junior Member

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    I do have a dashcam that turns off when the car is off. Now that you mention it, I wonder if it draws power when I have the car off. I also have two USB cables plugged in.

    How would I go about asking if there's some sort of monitoring gadget on the car? This is a good point though.
     
    #8 Halcykon, Apr 14, 2020
  9. bisco

    bisco cookie crumbler

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    idk how to measure the load. if no one here can help, there are other 12v threads with information.

    check your manual, i believe gen 4 sks can be shut off with the fob.
     
    #9 bisco, Apr 14, 2020
  10. Mendel Leisk

    Mendel Leisk Senior Member

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    #10 Mendel Leisk, Apr 14, 2020
  11. CooCooCaChoo

    CooCooCaChoo Active Member

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    Yeah, even if you are locked down due to the epidemic, should at least go sit in the car with it turned on for 20 minutes so the 12v doesn't die.

    I drive my 2017 every other day for about 20 minutes going to the grocery store.
     
    #11 CooCooCaChoo, Apr 14, 2020
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