1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Odd "runaway" RPM surge

Discussion in 'Gen 2 Prius Main Forum' started by nfschlaack, Sep 26, 2011.

  1. nfschlaack

    nfschlaack Junior Member

    Joined:
    Feb 28, 2007
    93
    3
    0
    Vehicle:
    2004 Prius
    OK first off, I want to state that this was NOT an uncontrolled "runaway" episode, but it was something unusual. I was at a stoplight today and unexpectedly, I had a a very high surge in RPM's with no input from me. To add, the battery was full, and the car had been running for more then fifteen minutes in almost 70 degree weather. So, It was not the car "recharging" itself. It was way higher than usual for that. Also, I've had my Prius new off the lot since 2004, so I've gotten to know the cars little idiosyncrasies and this was a new one. Like I said before when it revved, I was at a stoplight. I even released pressure off the brake pedal out of curiosity and it didn't move. The whole episode lasted about 10 seconds and took about 3-5 seconds to come out of it.

    So what could have caused this? I have no concerns out of my curiosity, but it's just that. I'm curious.
     
    #1 nfschlaack, Sep 26, 2011
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,796
    48,996
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    baterry was probably 'offing' some extra charge. no worries.:)
     
    #2 bisco, Sep 26, 2011
  3. qbee42

    qbee42 My other car is a boat

    Joined:
    Mar 2, 2006
    18,058
    3,073
    7
    Location:
    Northern Michigan
    Vehicle:
    2006 Prius
    When a Prius HV battery has a very high State of Charge (SoC), the Prius will work hard to bring the SoC back to more normal levels. If the Prius is standing still, it can't do much to help, so it burns of excess charge by spinning the engine with MG1. The engine is not running; it is used as an air pump to load MG1 and burn off charge.

    In this situation, generally the engine will race for a few seconds, stop, race again, stop, and so on until the SoC is reduced to an acceptable level.

    Tom
     
    #3 qbee42, Sep 27, 2011
    1 person likes this.
  4. nfschlaack

    nfschlaack Junior Member

    Joined:
    Feb 28, 2007
    93
    3
    0
    Vehicle:
    2004 Prius
    OK, great. Many thanks for the info.
     
    #4 nfschlaack, Sep 27, 2011
  5. nfschlaack

    nfschlaack Junior Member

    Joined:
    Feb 28, 2007
    93
    3
    0
    Vehicle:
    2004 Prius
    Tom,

    Your answer gave me another question. Being an '04, does this event say anything about the long term health of the battery? One would assume that if it holds a full charge and then some, that the battery is in great shape. But you know what they say about assuming. ;)
     
    #5 nfschlaack, Sep 27, 2011
  6. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,796
    48,996
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    it really doesn't say anything about the long term health of the battery, but, odds are, your battery is in excellent condition based on long term statistics.
     
    #6 bisco, Sep 27, 2011
  7. qbee42

    qbee42 My other car is a boat

    Joined:
    Mar 2, 2006
    18,058
    3,073
    7
    Location:
    Northern Michigan
    Vehicle:
    2006 Prius
    This is normal behavior for a good battery, so we can't really infer anything from it. As bisco stated, HV battery problems are rare.

    Tom
     
    #7 qbee42, Sep 28, 2011
  8. nfschlaack

    nfschlaack Junior Member

    Joined:
    Feb 28, 2007
    93
    3
    0
    Vehicle:
    2004 Prius
    Thanks again for the info guys. It's feedback from people like you that make it a pleasure to come to PriusChat.
     
    #8 nfschlaack, Sep 28, 2011
(You must log in or sign up to post here.)