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

Energy Monitor displays odd car behavior

Discussion in 'Gen 2 Prius Technical Discussion' started by unmesh59, Nov 23, 2013.

  1. unmesh59

    unmesh59 Junior Member

    Joined:
    Jul 22, 2010
    49
    9
    0
    Location:
    SF Bay Area
    Vehicle:
    2016 Prius
    Model:
    Two
    Now that my 2007 Prius has 140K miles on it, I'm monitoring its behavior more carefully then previously and have noticed a couple of odd things on the Energy Monitor. Both things are when the car is at a complete stop, say at a traffic light.

    First example, the ICE is off and the display shows that power is flowing from the battery to the wheels. This happens for the entire duration of the stop which can be more than a minute.

    In the second situation, the ICE is running (probably to charge the traction battery) but the Energy Monitor does not show any power flowing.

    Is this worth investigating further? If so how?

    I have an OBD II reader and Torque Pro if that helps.

    Thanks.
     
    #1 unmesh59, Nov 23, 2013
  2. cwerdna

    cwerdna Senior Member

    Joined:
    Sep 4, 2005
    12,544
    2,123
    1
    Location:
    SF Bay Area, CA
    Vehicle:
    2006 Prius
    For the 1st part, you're probably not pressing on the brake hard enough.

    For #2, try shutting off the HVAC completely (no auto and no fan). See Why mileage gets worse in winter | PriusChat re: better heater management.
     
    #2 cwerdna, Nov 23, 2013
  3. nh7o

    nh7o Off grid since 1980

    Joined:
    Dec 10, 2011
    1,686
    338
    0
    Location:
    Hawaii
    Vehicle:
    2009 Prius
    Model:
    II
    For #2, also check that the 12V battery voltage is OK. Should be initially 14.2V or thereabouts, dropping to 13.8 or a bit less. If it is hanging around 13 or lower, then there is a problem with the battery that is keeping it from getting fully charged (shorted cell). That will keep the engine on too.
     
    #3 nh7o, Nov 24, 2013
  4. AzWxGuy

    AzWxGuy Weather Guy

    Joined:
    May 22, 2011
    968
    490
    0
    Location:
    Tucson, AZ
    Vehicle:
    2021 Prius
    Model:
    Limited
    I've noticed that my 08 does this sometimes too. I hadn't thought that it was an indication of a problem though. I have been working through a 12V aux battery capacity problem lately with the Optima folks. Still testing and evaluating. When it is load tested (at AutoZone) it checks out fine, but the MFD test will show voltages about .2 to .4 below the minimum recommended. I haven't calculated what the voltage offset is yet, comparing MFD measurements to DVOM readings directly from the battery. I have read that the MFD is typically about .2 volts low. I wouldn't expect a marginal 12V aux to cause problems like this while the vehicle is "ready". I would expect somewhat lower mpg with the ICE trying to charge that battery. I wonder what a Toyota Service Advisor would say about this strange Energy Monitor display. They would probably want you to duplicate the indications or record a video of it misbehaving.
     
    #4 AzWxGuy, Nov 24, 2013
  5. usnavystgc

    usnavystgc Die Hard DIYer and Ebike enthusiast.

    Joined:
    Jul 29, 2011
    3,159
    988
    0
    Location:
    Tucson, AZ
    Vehicle:
    2005 Prius
    Model:
    Four
    Both situations are absolutely normal. The first one will go away if you press the brake pedal harder. The second one is because the ICE needs to heat up either for emissions purposes or to provide heat for occupant comfort. It's not charging the battery because the battery is likely already in the "sweet spot" of 6 bars.
     
    #5 usnavystgc, Nov 26, 2013
(You must log in or sign up to post here.)