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12v Battery or HV Battery Question

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by TMN_Guy, Aug 26, 2020.

  1. TMN_Guy

    TMN_Guy New Member

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    Hello to all,

    I have a question about the 12v or maybe the HV battery.

    When I am parked in Ready mode, I have noticed that the ICE restarts alot more often than it used too.

    Before, when I would park in ready mode with the AC on, it used to take about 20 minutes before the ICE would turn on and then it would charge for 2-3 minutes before shutting down.

    Lately though, the ICE turns on after about 10 minutes and still takes about 2-3 minutes to charge.

    My question is, is the 12v battery going bad, or is the HV battery not holding a good charge?
     
  2. burebista

    burebista Active Member

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    What I see on my Prius is that AC is running on HV battery. So emptying HV battery depends on AC temperature and fan speed.
    If I have an (almost) full HV battery and AC and fan on low it takes a while until HV battery is drained and ICE kicks in.
    But if HV battery is low/middle charged and fan on middle/high HV battery is drained fast.

    At least this is the behavior on my car.
     
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  3. sam spade 2

    sam spade 2 Senior Member

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    How long ago was "used to" ?
    It might be WAY hotter out now than it was then, running the AC harder and using more power.
     
  4. bisco

    bisco cookie crumbler

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    how many miles on her?
     
  5. TMN_Guy

    TMN_Guy New Member

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    I purchased a Veepeak OBD2 scanner in May. That is when I started paying attention to the battery cycles.

    My Prius is a 2012 and currently has 130,000 miles on it.
     
    #5 TMN_Guy, Aug 29, 2020
    Last edited by a moderator: Aug 30, 2020
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  6. jerrymildred

    jerrymildred Senior Member

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    Assuming similar states of charge for the traction battery and similar temperatures and other loads, if it's starting the engine sooner than it used to because of the A/C load, that's a sign that the traction battery is loosing capacity.

    Dr. Prius or Techstream will help you to put some numbers on the condition.
     
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  7. ChapmanF

    ChapmanF Senior Member

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    "The A/C load" can vary, though, from over two thousand watts, to a couple hundred at lowest continuous power and less than that with on-off cycling. All depending on a bunch of things like ambient temperature, insolation, and humidity.

    Unless you're keeping very close tabs on those factors (or have something like a ScanGauge plugged in showing A/C watts directly), it's hard to conclude much about the battery from how fast it drains under the A/C load. 2000 watts will certainly drain it faster than 200.
     
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  8. sam spade 2

    sam spade 2 Senior Member

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    Like I said, it is a LOT hotter now than it was in May.
    You are not leaving the OBD device plugged into the car when it is OFF, are you ?
     
  9. TMN_Guy

    TMN_Guy New Member

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    I just purchased the paid version of Dr. Prius and ran the battery life expectancy test and, assuming I did it right, it says the HV battery is at 70%.

    No. I don’t leave it plugged in.
     
    #9 TMN_Guy, Aug 30, 2020
    Last edited by a moderator: Aug 30, 2020
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  10. bisco

    bisco cookie crumbler

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    sounds like you're fine
     
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