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

Full charge engine goes on and off

Discussion in 'Gen 2 Prius Main Forum' started by danl, Jan 21, 2010.

  1. danl

    danl New Member

    Joined:
    Jan 26, 2009
    231
    6
    0
    Location:
    Boston, MA
    Vehicle:
    2009 Prius
    Solved - Full charge engine goes on and off

    I think this topic has come up before and I do recall reading that it was normal behaviour. But now that its been happening to me I'd just like to ask and make sure a trip to the dealer is (hopefully) not necessary.

    So on my morning daily commute to work, I glide down this long and moderately steep section of Rt2, at the bottom of which is a stop light. On 4/5 days, at the bottom of the hill, I'm at a full charge on the battery, 10 bars full green. Sometimes, when in that scenario, I notice the engine kicks on for a second, then off for a second, then on, then off, repeatedly until the light changes and I start moving again.

    My guess is that the battery is over charged and the car is trying to dump excess energy, but any insight/confirmation is appreciated. And if the car needs to dump the energy, why not just keep the engine on. Why go on and off and on and off?

    Ty
    -Dan
     
    #1 danl, Jan 21, 2010
  2. qbee42

    qbee42 My other car is a boat

    Joined:
    Mar 2, 2006
    18,058
    3,075
    7
    Location:
    Northern Michigan
    Vehicle:
    2006 Prius
    You are correct. The control system is bringing down the battery SOC by spinning the ICE as a load. Doing it in bursts allows for more accurate monitoring of the SOC, as the battery is not under heavy load between bursts.

    Tom
     
    #2 qbee42, Jan 21, 2010
    1 person likes this.
  3. danl

    danl New Member

    Joined:
    Jan 26, 2009
    231
    6
    0
    Location:
    Boston, MA
    Vehicle:
    2009 Prius
    Thanks Tom. That works for me. I wish it wouldn't do that at the stop light though. Sometimes during the summer, people pull up besides me with their windows down and give me a questioning look as if saying "whats wrong with your hybrid?"
     
    #3 danl, Jan 21, 2010
  4. ksstathead

    ksstathead Active Member

    Joined:
    May 1, 2007
    1,244
    245
    0
    Location:
    Kansas
    Vehicle:
    2010 Prius
    Model:
    III
    If you can EV (not necessarily EV mode) to reduce SOC before the descent, then it might not get full enough to compel the waste. Or you can use B on the descent to reduce regen, but better to use the EV before the crest and stay in D.
     
    #4 ksstathead, Jan 21, 2010
  5. Bobsprius

    Bobsprius BobPrius

    Joined:
    Jul 23, 2009
    679
    80
    0
    Location:
    Buffalo
    Vehicle:
    2010 Prius
    Model:
    V
    "whats wrong with your hybrid?" Anyone giving you that look, say "nothing at all, my car is cycling using less gas while your's is running CONTINUOUSLY wasting gas!" ;)
     
    #5 Bobsprius, Jan 21, 2010
  6. john1701a

    john1701a Prius Guru

    Joined:
    Jan 6, 2004
    12,769
    5,252
    57
    Location:
    Minnesota
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    Re: Solved - Full charge engine goes on and off

    That assessment of dumping is correct; however, the engine isn't going on and off. The motor just spins it to consume electricity (for the sake of battery longevity). So, what you are feeling is just RPM changes. It never actually starts.
    .
     
    #6 john1701a, Jan 21, 2010
    1 person likes this.
  7. bagwell

    bagwell Active Member

    Joined:
    Sep 14, 2005
    592
    49
    0
    Location:
    the woodlands, tx
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Advanced
    Re: Solved - Full charge engine goes on and off

    very cool...!
     
    #7 bagwell, Jan 22, 2010
(You must log in or sign up to post here.)