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motor kick in when the battery is fully charge

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by hc167, Mar 25, 2009.

  1. hc167

    hc167 Member

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    I have a question and hope someone can answer. I live on a hill. so when I go downhill and at the stop sign, my MFD shows that the battery is fully charged with all eight green bar. and when I am at the stop sign, I did see that the battery is powering the wheel and the MFD show the arrow from the battery to the engine. and I also realize that either the motor or the engine is on. Is this normal? anyone have this experiment??
     
    #1 hc167, Mar 25, 2009
  2. efusco

    efusco Moderator Emeritus
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    It's normal, more than likely you're not yet fully warmed up which is why the ICE continues to run.

    What I thought you were going to ask is why the engine cycles on and off when the battery is full...that is also normal...it takes a bit of energy to cycle MG1 and crank the ICE. Doing that a few times drains the battery down to a level closer to its "ideal" 60%.
     
    #2 efusco, Mar 25, 2009
  3. qbee42

    qbee42 My other car is a boat

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    Adding to what Evan has explained, if the battery is charged all the way up to the top limit, the Prius will try to bring the state of charge down. If you are moving, it can do this by using more battery power, but sitting still it only has one option: spinning the engine. The Prius uses the engine as a dead weight and spins it with the electric motor to burn off excess charge. It will spin it, stop, check the state of charge, spin it again, and so on.

    It's completely normal.

    Tom
     
    #3 qbee42, Mar 25, 2009
  4. Mike Dimmick

    Mike Dimmick Active Member

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    This can also happen once the car is fully warmed up but you haven't yet let it do an idle calibration (at least, that's my guess of why this behaviour exists). In that situation, it will start the engine when you slow down from around 30mph.

    Slow to less than 6mph, take your foot off the gas, and wait about ten seconds for it to stop the engine. It will then allow the engine to stop below 30mph. Some people refer to this as 'Stage 4' - see Five Stages of Prius Operation.

    I've started to see this behaviour more now that I drive in no-battery mode, where possible. (That is, accelerating so that all generated power goes to the motor, and no more; gliding to an upcoming speed limit, junction or traffic light.)
     
    #4 Mike Dimmick, Mar 25, 2009
  5. hc167

    hc167 Member

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    I do not understand that. the MFD show that the motor is powering the wheel, whereas I can hear the sound of both engine and motor. So is the motor try to spin the engine to discharge the battery? even if the motor is trying to spin the engine to discharge the battery, I do not see any reason why the engine should kick on unless both MG1 and MG2 are both kick on to discharge.
     
    #5 hc167, Mar 25, 2009
  6. qbee42

    qbee42 My other car is a boat

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    If it is burning off excess charge, then the engine is not "on", it is simply a source of friction being spun by MG1. In this situation you will hear the engine, but it will not be displayed as running on the MFD, since it is not providing power. The MFD shows power, not whether the engine is running or spinning.

    Tom
     
    #6 qbee42, Mar 25, 2009
  7. richard schumacher

    richard schumacher shortbus driver

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    You can hear the engine in this mode because it's pumping air, a lot of it, under considerable pressure.
     
    #7 richard schumacher, Mar 25, 2009
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