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2011 Prius poor fuel economy in AZ

Discussion in 'Gen 3 Prius Fuel Economy' started by 11priusowner1955, Jul 11, 2015.

  1. cyclopathic

    cyclopathic Senior Member

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    I don't think TechStream would show all dynamic conditions, unless they test it under the load.

    Sounds like you have access to Torque app or similar ODBII tool. Gen3 reports the difference in voltage btw modules on OBD2. The way we checked my battery with co-worker we took it for a ride and looked at deltas. The delta on mine ('10, 160K) was almost as good as on his ('12, 65K), less than 0.25V at heavy load, and with momentary transitional readings of 0.5V. The delta readouts are the tale signs of static voltage output and internal resistance. It is quite possible that some modules in you hybrid battery are going bad and the side effects you see (additional heat and losses) are the result of it. It has to be still within specs, otherwise ECU would have thrown code.

    Second, you can plot 12v battery too it should be reported on OBD2 (at least it is on C). Check the voltage when you turn car on but ICE isn't yet, and impact of turning headlights on/off. OF cause you can do it with voltmeter off terminals. What failing 12V does to Prii besides additional drag I am not 100% sure, perhaps lowered voltage effects electronics?
     
  2. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Take a bit of caution with this:
    The NHW11 uses a 'sample and hold' technique where a capacitor is used to hold the module-pair voltage before reading the value. If the car is going through transitions, say charging to a discharge mode, the samples could be taken on either side giving a false, high dV. A better technique is to put the car in a known state and take the readings. Taking them on the fly is . . . subject to sampling errors.

    Bob Wilson
     
  3. Tim Bender

    Tim Bender Member

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    I've struggled with our 2011 as well - it used to take all my effort to get anything above 45MPG. We have to park on-street at home and my wife used to drive the prius to work so it sat in the sun all day.

    I just started driving the Prius to work about a month ago (wife has a new car) and I park in a parking deck. In the afternoon when I head home the cabin is very cool - I can drive comfortably with the climate control set to 78F (with A/C on) even in 95-100F outdoor temps (with humidity). I'm easily surpassing 50 MPGs now.

    The sun was killing us.
     
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  4. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    The irony is that our friends to the north are seeing this on their warmer days in the sun now, too!
     
  5. SageBrush

    SageBrush Senior Member

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    Playing around with the battery conditioning is interesting but we should not neglect the elephant in the room: A/C used for cooling the entire car.
    1. Park in the shade
    2. If not possible, park facing the sun and put up a sun shade on the front windshield
    3. Crack windows open for ventilation
    When I was a boy car owners used to take the time to place a whole car cover. It might be interesting to know how much the car can be cooled down in a dry climate by watering down the car with a cover and letting it evaporate. I thought about this at home but then got lazy.
     
  6. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    All things I could try @ home, but not @ work. Parking at work is hit or miss, but nose into the sun is usually possible. I already use a sun shade, and opt for nose to sun where practical.

    I do find that tail to the sun can drive battery temps as high as 55-58°C, even w/ tonneau cover closed. This is especially noticeable when taking a trip, then parking tail to sun, and driving 1-2 hours later after the battery has been chemically active.

    A/C with fan in fresh mode after the first 5-10 minutes will drop the battery at least 3°C for a 20-25 min trip.

    I've also just ordered a new 12V ( Amazon.com: Optima Batteries 8171-767 (DS46B24R) YellowTop Prius Battery: Automotive )
     
  7. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    12V replaced today w/ an Optima Yellow Top. As expected, no improvement there in the short term. Once I get back from vacation, I'll look at other options, incl dust in the battery, etc. When I checked the fan somewhat recently, it was clean.
     
  8. cyclopathic

    cyclopathic Senior Member

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    Check that it operates smoothly. Perhaps fan bearings dried out and it does not get the needed RPMs for flow.
     
  9. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    From the steady wooshing sound at high fan speeds, I'm not too concerned that it's not running smoothly, but next time I'm in there, I can do that again. Also, no sounds of spun bearings.

    Any ideas on whether they're ball or sleeve style?