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Outside temp kicks engine on?

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by Greg_M, Nov 17, 2015.

  1. bisco

    bisco cookie crumbler

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    i think it might be a combination of factors, but if all you did is hit the start button and it fired up, that's surprising at 32 degrees. i run on pure ev all winter long down into the teens, and only have the ice come on at one particular spot in my commute if i'm not careful.
     
  2. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    There are (at least) two outside air temperature factors:

    1) There is the one where the climate control system is calling for cabin heat, about 59 F.

    2) And there is another, much lower, temperature, at which the ICE will come on even if no cabin heat is being asked for.

    3) And possibly there is battery low temperature trigger. (Unless that is actually #2.)

    Only the Toyota engineers know. There is apparently no publicly disclosed information about this.
     
    #22 CharlesH, Nov 17, 2015
    Last edited: Nov 17, 2015
  3. bisco

    bisco cookie crumbler

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    he didn't have cc on, so it must be #2 and 3. but 32 degrees ambient is way too high.
     
  4. The Electric Me

    The Electric Me Go Speed Go!

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    I understand the difference.
    Since the OP's profile say's 2004 Prius, I assumed he wasn't talking about a pip.
     
  5. The Electric Me

    The Electric Me Go Speed Go!

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    Keep in mind that the machine,- has no idea whether the trip is going to be short.
    So you can sit in the drivers seat and "know" the trip could easily be accomplished in EV mode, but The Prius doesn't know this.

    The Prius is going to make operating decisions based on things it IS capable of knowing. Such as Battery Charge level or engine temperature.

    I don't think anything too much more complicated than.....when the engine is cold it will run is happening here.
     
  6. Greg_M

    Greg_M Member

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    Right, the car doesn't know so it should do what I tell it to do. If I put it in EV mode and I'm not accelerating hard or calling for heat then the ICE should not come on until the EV "portion" of the battery has been used. My question was, is there an OAT override that forces the ICE to come on even when the situation isn't calling for the engine?

    I appreciate people's responses but I ask you to reread my original question because your answers have had nothing to do with it. I'm not trying to be disrespectful but I think you misunderstood what I was asking.

    BTW, my signature states the cars I currently have but I've gone ahead and changed my profile to match.
     
  7. mmmodem

    mmmodem Senior Taste Tester

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    We did not misunderstand your question. Bisco answered your question on post 2. This thread continued on only because we don't think temperature is what caused the ICE to turn on in your description.
     
  8. Greg_M

    Greg_M Member

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    My last answer was to the post right above it, not to everyone in the thread. I guess I can't assume that people will make the connection and I'll have to include quotes from now on. Sorry about the confusion.
     
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  9. john1701a

    john1701a Prius Guru

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    Here's a video driving my Prius PHV at -2°F without the heater... electric-only for 9 miles, no engine:

     
  10. john1701a

    john1701a Prius Guru

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    Here's that same route at -10°F while filming output from the Torque app:

     
  11. john1701a

    john1701a Prius Guru

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    Yes, extreme cold outside while parked at work will cause that.

    Those 2 videos show me on my commute to work, after having left an insulated but unheated garage. That's just barely enough to keep the battery warm'ish overnight. Sitting outside in the exposed parking lot all day in sub-zero F temps, the engine will start at about 25 mph. So, on the commute to home, I lose EV right away. The system still draws from the pack, but it's in the form of EV-BOOST instead.

    Sorry, I don't know the specific combination of outside & battery temperatures to trigger that. But in such cold, I want the heater running anyway.
     
    #31 john1701a, Nov 18, 2015
    Last edited: Nov 18, 2015
  12. Greg_M

    Greg_M Member

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    So at 32 the OAT should not have made the ICE come on. When it happened I checked the CC and it was off. Since the engine was already running I turned the CC on so I could check the temp setting (I'm not the only driver of the car). It was set above LO so I lowered it and turned the CC back off. I was either backing out of the driveway or right after I put it into drive when the ICE came on. It can't be hard acceleration because my driveway is 1 house from the stop sign at the corner. I also know for a fact that the engine had run within the previous couple of days so there's absolutely no way it came on because of continuous EV mileage.

    I can't think of any other reasons that might have caused the engine to come on. Of coarse Bisco mentioned that it can come on randomly at below 40. To me that would indicate a flaw in the programing if it truly is random. If that's the only logical answer then it's like someone else mentioned, Toyota hasn't given out enough info for anyone to know exactly how the car determines the need for the ICE to come on. I just want to know why it came on so that if it was something I did I can avoid it in the future.

    Just thought of something. This question is about the maximum EV miles the car can go before the ICE will come on. At what point does the programing acknowledge the engine ran so that it counts towards resetting the maximum EV miles? What I mean is, does the ICE have to reach a certain operating temp or does it just have to turn on in order to reset that counter? There are many times that the engine will come on just as we get to our street. Another way to put it is that although it comes on it doesn't have anywhere near enough time to reach 130 before it's turned off.
     
  13. bisco

    bisco cookie crumbler

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    charging is a factor. do you charge outside greg?
     
  14. john1701a

    john1701a Prius Guru

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    That's the key. There is the need for "housekeeping" events, where emissions are collected for cleansing at a later time with the hope of more heat being available then. We have no idea what the criteria is for that to happen. But the engine running unexpectedly or at a higher RPM than usual would be an indicator of that.

    We don't know that either... again, it's emission control stuff. The engine will sometimes run a full warm-up cycle even when the coolant temperature is at 165°F. I notice that after a hard-acceleration following a long drive in EV.
     
  15. Greg_M

    Greg_M Member

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    Yes, no garage so charging (240v) and parking is outside.

    John
    Thanks for the response. Wish I could know exactly what's going on but I guess I'll just have to continue to just try to control what I can control to maximize EV.
     
  16. bisco

    bisco cookie crumbler

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    yep. we'll never know exactly what's going on. there are plenty of threads here where we discussed it, but never came to any conclusions.
     
  17. The Electric Me

    The Electric Me Go Speed Go!

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    Sorry, I looked at your ORIGINAL profile which only stated 2004 Prius.- Bout time you updated that.
    I'll excuse myself from further commentary as I don't own a PiP.
    Good Luck finding your answer.
     
  18. giora

    giora Senior Member

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    Did you use the timer to finish charge close to your departure in this day when the ICE turned on?
    Could be a very cold night and charging is warming the battery.
     
  19. Greg_M

    Greg_M Member

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    I don't bother with trying to time the charge with when the car will be used. Found no difference.

    How is warming the engine going to warm the battery? Someone earlier made a comment that a cold battery might cause the engine to come on.
     
  20. mmmodem

    mmmodem Senior Taste Tester

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    The act of charging a battery warms it up. If you set the timer to finish charging right before you start the car, then the battery will already be warm instead of cold. You also get the added benefit of residual heat in the cabin. I don't think warming the engine warms the battery unless you call for cabin heat. However, if the battery is cold, the may engine comes on. I'm not sure why because same as the engine, the battery will warm up as you start discharging it.