low traction battery in the morning

Discussion in 'Gen 4 Prius Main Forum' started by vlaxes, Sep 10, 2021.

  1. vlaxes

    vlaxes New Member

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    Hi
    I have recently bought a 2018 prius one, very excited with the car, but I noticed something and wanted to check if that's the expected behavior.
    I drive the car in the afternoon, leaving the car in a parking garage overnight. When I park the car in the evening the traction battery is almost full, but when I start it in the morning there are one or two bars left of battery. Is that normal?
    I am sure I am powering the car off completely, and there are no devices connected to the car.
    Car has 27k miles, and I live in South Florida if that helps.
    Thank you in advance for your help.
     
    #1 vlaxes, Sep 10, 2021
    Last edited by a moderator: Sep 10, 2021
  2. jdenenberg

    jdenenberg EE Professor

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    When your Prius is turned off, the HV battery is actually disconnected from the rest of the car and split into two lower voltage series strings of cells so this is not a normal behavior. If your battery is actually losing significant energy when off there could be corrosion on the battery bus bars causing a current leakage path. This can be repaired at a reasonable cost, but requires care as the voltage is high enough to kill you. If there were a conductive path to the car body, there would be error codes as this is a safety issue.

    Since you are in Florida, your battery may have been overheated which could affect battery capacity. Using an inexpensive OBD2 dongle and the DRprius app on an android device would allow you to see codes and check your battery health.

    JeffD
     
  3. vlaxes

    vlaxes New Member

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    Thank you very much for taking the time to respond. I am going to the dealer tomorrow, I will let you know the outcome, but I am not very optimistic... let's see. If they do not solve it I will try the OBD2, thanks.
     
  4. sam spade 2

    sam spade 2 Senior Member

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    That's a BIG if.

    What he is seeing may not be ABnornal at all.
    Several owners across different models have noticed the same thing.

    It likely depends on how quickly the displayed "state to charge" goes back up near to the top.
    When I've noticed that with my C, it is back up withing a couple of miles/minutes.......leading me to believe that the computer just needs to read all the inputs to "update" the display.
     
  5. bisco

    bisco cookie crumbler

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    not normal. can you get a pic in the evening, then the morning?
     
  6. MPGboss

    MPGboss Junior Member

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  7. CooCooCaChoo

    CooCooCaChoo Active Member

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    Look at the brightside, the hybrid battery has an 8 year/100k mile warranty. Toyota will replace for free if it fails in that timeframe.
     
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  8. jerrymildred

    jerrymildred Senior Member

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    You have about four or five years or 73k miles left on the battery warranty. If it's bad, you're not out anything but some time without the car.

    There might be some kind of internal drain on the battery, but I'm pretty sure it would throw a code. It seems more likely that even though you're sure you shut it off, you actually didn't. I think just about every Prius owner has done that a time or two. The way to know for sure if you shut it off is the insulting message that pops up on the MID when you open the driver's door telling you to put your foot on the brake pedal and press the start button. And, if you didn't shut it off and missed the message, the act of starting it will actually shut it off. ;)
     
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  9. Henrik Helmers

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    Something to keep in mind is that the battery display is not perfectly accurate, and takes a while to stabilize. So if you drain it quickly before turning it off, that might explain some loss. Another factor is temperature changes.

    If you drive slowly before parking and park in a garage at constant ~20C I would expect it to be stable for days.
     
  10. FuelMiser

    FuelMiser Senior Member

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    Post some pics of the State of Charge when you shut off at night and again in the morning, so we can be sure you are looking at the correct display.
     
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  11. vlaxes

    vlaxes New Member

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    sorry it took me longer to have some feedback.
    I went to the toyota dealer in Weston, FL. Where I bought the car a month ago. The "prius" guy reviewed the car, gave me the report and said that everything was working as designed. No code errors in the report.
    I bought the ODBII device and used it with the app, I attached the screenshots, from my perspective there are several cells not working correctly, but I may be wrong....
    The issue is still the same, hybrid battery is charged when I leave the car at night and discharges overnight. It only has 2 bars the next morning.
    Can someone confirm my assumptions? should I try with another mechanic? Thank you in advance for your feedback.

     
  12. davecook89t

    davecook89t Senior Member

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    The graphics in the screen shots don't make sense. The Voltage Difference is .08V and .10V, perfectly normal for a new battery, but the voltages shown on the bars of the graph show a difference of ~ 16V. Apparently, the app is combining the results from the 10 middle blocks, showing 4 modules in each block, instead of the normal 2. This is from Dr. Prius, correct? I would be more suspicious that the app is malfunctioning, rather than the battery to produce those graphics. The loss of charge overnight is a concern, to be sure, but first you need to find out why the app is not showing accurate results. Perhaps try re-installing it. If that doesn't work, reach out to @jacktheripper, who created the app, he may be able to tell you what's wrong.
     
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  13. Pulse07

    Pulse07 Member

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    are you locking the car? And are all the keys out of the car?
     
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  14. sam spade 2

    sam spade 2 Senior Member

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    NO. Your main assumption is that the DISPLAY you are looking at is accurate......and it may not be at all.
    It is not put there as an aid to any kind of technical analysis but just for a general idea of what is going on.

    Like I said before, showing 2 bars in the morning might be some kind of default that the computer needs to update before giving you a better "picture". I have seen similar things happen and there is absolutely NO problem.
     
  15. jerrymildred

    jerrymildred Senior Member

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    @davecook89t is right. There's something screwy with the Dr. Prius report. It can't be both a 16V difference and a 0.10V difference at the same time.

    One thing the dealer tech might not have thought of: relays can stick. I replaced lots of them in my industrial electrician years for that reason. It's unlikely, but it is possible that the relay connecting the battery to the car could stick. However, iirc, there's an auxiliary contact to monitor the state of the relay and the car would throw a code if the relay wasn't in the correct state.
     
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  16. Ramo_958

    Ramo_958 Junior Member

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    I also have a 2018 Prius One, but with 85k miles. A couple of weeks ago I went for a week vacation. Before I left the battery was almost fully charged and when I came back a week later it was the same.
    Posted via the PriusChat mobile app.
     
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  17. CooCooCaChoo

    CooCooCaChoo Active Member

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    Oh yeah, my old Gen 2's hybrid battery did the same thing. Full at night, discharged some in the morning. Next thing I know it failed.
     
  18. alanclarkeau

    alanclarkeau Senior Member

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    How old was it at that stage? I've only read about it in some quite old batteries.
     
  19. CooCooCaChoo

    CooCooCaChoo Active Member

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    I think it was the original. It last some 13-14 years and like 120k miles if it was.
     
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  20. vvillovv

    vvillovv Senior Member

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    Those screenshots of DrPrius above look almost like they were taken in a Prius C or Yaris , almost.
    My first thought is your OBD2 bluetooth adapter. If that is the case you might want to check out the app developers tested adapters page Hybrid battery diagnostic and repair tool for Toyota and Lexus -> What OBD2 adapter to buy
    in the nav menu at the top of the page.
     
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