Battery has range, but doesnt work properly.

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Shimano Teryaki, Mar 3, 2026 at 1:38 PM.

  1. Shimano Teryaki

    Shimano Teryaki New Member

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    Hello,
    I own a 2010 Gen 3. I bought it last year, but i have experience with other Toyota hybrids, both newer and older and have never seen something like this, and i think neither did my local toyota dealership.

    When i bought the car in october everything worked fine, just as intended. Got the consumption around 4 - 5 l/100km. At some point however on a random tuesday it started going crazy, it wasnt a gradual change, it just happened.

    Getting to the problem since it started whenever i drive the car, it goes into this never ending cycle. Lets say that i start the car and the battery is at one bar. ICE will be charging the battery for about 5 - 10 minutes and it will be one bar for the entire time. At some point the ICE stops and the battery fills up to 100% in a matter of 30 seconds. Then if im in a traffic jam, ICE will start going crazy fast, WITHOUT burning fuel (at least the fuel consumption says 0 when im driving without gas pedal and ICE is still revving like its going to explode, i suppose to get rid of excess energy.) however if this overcharge of traction battery happens on some country road when i can just drive at 70km/h then i will get like 5km (i checked a few times, its this much) of pure battery range. No matter which of this two cases happens the diagram says 100% the whole time and then at some point it goes to one bar again in a matter of 30 seconds.

    So basically the battery has the range, but it looks like the computer doesnt know the real charge value.

    This started to happen before it got colder for the winter, im stating it because toyota dealership told me multiple times everything is fine with the car, its just the temperature.

    Also these 30 second percentage changes happen no matter what. Even if im driving only using the battery uphill, it will still charge from 0% to 100%

    No lights on the dash, no warnings, no errors. Consumption is now at around 7l/100km and its like that since before it got cold

    pls help
     
    #1 Shimano Teryaki, Mar 3, 2026 at 1:38 PM
  2. Cornvalue

    Cornvalue New Member

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    That’s a top indicator of a bad battery / energy storage capacity unfortunately.

    Check battery cell resistance with OBD.
     
    #2 Cornvalue, Mar 4, 2026 at 2:32 PM
  3. bisco

    bisco cookie crumbler

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    Get a free 12 volt load test at most auto parts stores
     
    #3 bisco, Mar 4, 2026 at 2:35 PM
  4. Cornvalue

    Cornvalue New Member

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    Our family tip: if you cannot get battery to atleast green or almost top charge, it’s lame.

    If you try R and back up a hill - if the battery UI will indicate empty / one bar after 10 meters it’s bad.

    Reverse only use the HV battery.
     
    #4 Cornvalue, Mar 4, 2026 at 2:35 PM
  5. Cornvalue

    Cornvalue New Member

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    How would 12V tester solve anything?

    Just use car scanner pro iOS and a vgate BT4 to check HV battery resistances and Voltage.
     
    #5 Cornvalue, Mar 4, 2026 at 2:37 PM
  6. bisco

    bisco cookie crumbler

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    If you’re getting 5km range without the engine coming on, the battery is fine
     
    #6 bisco, Mar 4, 2026 at 2:40 PM
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  7. Cornvalue

    Cornvalue New Member

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    But 12V sucks?
     
    #7 Cornvalue, Mar 4, 2026 at 2:46 PM
  8. indel

    indel Member

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    Capacities on multiple modules has diminished substantially such that they can go from no charge to fully charged very quickly. Dr. Prius should be able to get you a glimpse into this problem.

    You will either have to replace the battery or refurbish it. There are a ton of videos on yt that show how to do this.
     
    #8 indel, Mar 4, 2026 at 2:46 PM
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  9. Cornvalue

    Cornvalue New Member

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    Oh my the focus on Dr Prius is just so tired. Use a capable app that can read any PID.

    This app only reads basic OBD values for voltage and resistance. Wow.
     
    #9 Cornvalue, Mar 4, 2026 at 2:53 PM
  10. Brian1954

    Brian1954 Senior Member

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    How many km on the car?

    Do you have any history about the car you bought? Has any work been done on the hybrid battery before or after you bought the car?

    My guess is a problem with the hybrid battery.
     
    #10 Brian1954, Mar 4, 2026 at 3:25 PM
  11. Shimano Teryaki

    Shimano Teryaki New Member

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    The thing is, before it happens ICE charges the battery for like 5 - 10 minutes. Only then the battery will go 10% to 100% in 30 seconds. Is it possible that somehow the system doesnt know how much charge ther is? Because both charge going up and down quickly happens after a long time of charging/discharging the battery. Is seems that the battery is fine, just the system cannot comunicate with it properly is it possible?

    I have papers saying that 220km is a legit mileage. Previous owner showed me photos of the battery being replaced a year ago, also showed me his text messages with the actual garage that done this, he said he lost the papers. It looked legit but well... He said the battery already had like 30k on it and he put another 10k so in theory it should have 40k by now

    Toyota dealership tested the battery and i got a paper that everything is fine with it. Are those dealership tests legit?
     
    #11 Shimano Teryaki, Mar 4, 2026 at 3:31 PM
    Last edited by a moderator: Mar 4, 2026 at 7:39 PM
  12. Brian1954

    Brian1954 Senior Member

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    The Dr Prius app is good for looking at data for the hybrid battery. Search for the website for the app and do some reading about it.

    Posted via the PriusChat mobile app.
     
    #12 Brian1954, Mar 4, 2026 at 8:32 PM
  13. bisco

    bisco cookie crumbler

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    no way to know without testing, but a weak 12v can make the eco's do funny things. it's always a good first step, low hanging fruit
     
    #13 bisco, Mar 4, 2026 at 9:24 PM
  14. Brian1954

    Brian1954 Senior Member

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    A weak 12v battery can not make the ECU's do funny things as long as the car is in READY, and the DC/DC converter is working properly to supply voltage to the 12v system of the car.
     
    #14 Brian1954, Mar 4, 2026 at 9:41 PM
    Last edited: Mar 4, 2026 at 9:50 PM
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  15. Brian1954

    Brian1954 Senior Member

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    The Dr Prius app does a lot more than just providing the values for voltage and resistance. Maybe you should learn the benefits of using the app. It provides the same information about the hybrid battery as Techstream does.
     
    #15 Brian1954, Mar 4, 2026 at 9:49 PM
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