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Not sure if my inverter is failing.......

Discussion in 'Gen 3 Prius Technical Discussion' started by JC91006, Sep 15, 2014.

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  1. JC91006

    JC91006 Senior Member

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    I have not done the recall on my inverter yet. Waiting til it breaks down. Today something strange happened!

    Checked my battery's health on my 2010 and noticed something strange. When in ready mode, I checked the voltage and it read 13.8 volts. While driving this voltage goes all the way down to 13.0 volts when I'm not accelerating. Once I stop, it goes back up to 13.8 volts, when I accelerate it stays at 13.8 volts, right when I take my foot off the gas, it drops to 13.0 volts. I can't understand this, there are no warning lights.

    I thought it might be a faulty battery, Yuasa battery from 2012, reads 13.1 volts when disconnected.

    Put in an Optima that read 12.9 volts to see if anything changes. The car in ready mode now reads 13.5 volts. Initially it also dropped to 13.0 volts for about the first 1 or 2 minutes of driving. Then it stays at 13.5 volts in ready mode. Doesn't go up or down like the old battery. Holds steady at only 13.5 volts and not 13.8 volts

    What the heck could be going wrong with this car? MPG has been dropping lately to about 40mpg. Still no warning lights.....

    Any ideas?
     
    #1 JC91006, Sep 15, 2014
  2. mrbigh

    mrbigh Prius Absolutum Dominium

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    It could be your Inverter, you are in a marginal zone of age/stress out part. Expend some money and have it diagnosed by a couple of reputable Toyota stealer centers.
     
    #2 mrbigh, Sep 15, 2014
  3. jdcollins5

    jdcollins5 Senior Member

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    The 2010 12V battery charging circuit should be in the neighborhood of 14.5 V. There is a temperature sensor attached to the battery brace that, according to the Repair Manual, will reduce the voltage to about 13.5 if the sensor temperature gets high.

    The 12V battery temperature sensor is also sensing the exhaust from the HV Battery blower motor that passes over the 12V battery to the exhaust vent. Are your HV Battery temps running high?
     
    #3 jdcollins5, Sep 15, 2014
  4. JC91006

    JC91006 Senior Member

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    It was over 100 degrees outside, so it could very well be hot when I drove it.
     
    #4 JC91006, Sep 15, 2014
  5. jdcollins5

    jdcollins5 Senior Member

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    Check the charging voltage the next time you start the car with the HV Battery cooled down. If it goes back to 14.5V and then decreases as the HV Battery warms up then I would say that it is working correctly.
     
    #5 jdcollins5, Sep 15, 2014
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Maybe do the recall? I can understand your reluctance, with the mixed reports, but at this juncture might be for the best.

    FWIW, we've got the recall, zero issues.
     
    #6 Mendel Leisk, Sep 15, 2014
  7. JC91006

    JC91006 Senior Member

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    I just started the car right now, it's reading 13.7 volts in ready mode. The car is relatively cool right now, I'm able to get the car in EV mode, if it's too hot, it won't engage into EV mode.

    I've never had a problem with the car, not even sure if this would be considered a problem. Other than the voltage readout, everything seems normal.
     
    #7 JC91006, Sep 15, 2014
  8. jdcollins5

    jdcollins5 Senior Member

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    I would just continue to monitor the charging volts for a while and see if it continues to be an issue.
     
    #8 jdcollins5, Sep 15, 2014
  9. JC91006

    JC91006 Senior Member

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    This 2010 of mine is so new to me, I'm not sure exactly what's different about it compared to the Gen II. I had no clue the charging voltage goes up to 14.5 volts and down to 13.5 when it gets hot. Great information to know about the GenIII
     
    #9 JC91006, Sep 15, 2014
  10. jdcollins5

    jdcollins5 Senior Member

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    I checked mine on the way home from work. HV Battery temps 92F after sitting in open parking lot, ambient about 75F. The 12V battery read 14.2 V and stayed constant until the HV temps hit 100F, then the charger cut back to 13.5 V. It bounced back and forth between 13.5 and 14.2 as I did numerous start/stops.
     
    #10 jdcollins5, Sep 15, 2014
  11. JC91006

    JC91006 Senior Member

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    Thanks for the info. What worries me is when it went from 13.8 volts to 13 volts when I took my foot off the accelerator, did this repeatedly. With the new Optima now, it's been steady at 13.7 - 13.5 volts. Our temperature here has been hottttt 105 degrees outside.
     
    #11 JC91006, Sep 15, 2014
  12. SageBrush

    SageBrush Senior Member

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    105F. Any chance you are using the AC just a weee bit more than usual ?
     
    #12 SageBrush, Sep 15, 2014
  13. JC91006

    JC91006 Senior Member

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    Yes the AC has been on constantly, but shouldn't lower my charging voltage. It may account for the missing mpg though.
     
    #13 JC91006, Sep 15, 2014
  14. SageBrush

    SageBrush Senior Member

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    You sure about that ?
     
    #14 SageBrush, Sep 15, 2014
  15. JC91006

    JC91006 Senior Member

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    hmmmm....on my GenII, it's constantly 13.8 volts regardless if my AC is on or not.

    The GenIII? Well I don't know what to expect on that
     
    #15 JC91006, Sep 15, 2014
  16. jdcollins5

    jdcollins5 Senior Member

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    Why would the AC have any affect on charging voltage ?
     
    #16 jdcollins5, Sep 15, 2014
  17. SageBrush

    SageBrush Senior Member

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    ok ... get ready to hear possible nonsense ...
    I presume the voltage is affected by the pressure head and the load. In the case of JC the last few days, his car has a high load and a variable head pressure as the ICE cuts in and out. I realize the system has a regulator upstream of the 12v, but there must be some delay to the system.
     
    #17 SageBrush, Sep 15, 2014
  18. jdcollins5

    jdcollins5 Senior Member

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    Yep. :)
     
    #18 jdcollins5, Sep 15, 2014
  19. JC91006

    JC91006 Senior Member

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    Found my problem, the readout on the navigation screen is showing .8 volts less than the actual reading at the battery terminals. My reading of 13.5 volts is actually 14.3 volts at the terminals.

    These readouts from the car can't be trusted
     
    #19 JC91006, Sep 15, 2014
  20. DaneH5

    DaneH5 Member

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    Are your terminals dirty? You are dropping 0.8 of one volt. Resistance in wiring/connections can account for the difference.
     
    #20 DaneH5, Sep 15, 2014
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