EV cancelled due to high speed while doing single digits MPH?

Discussion in 'Gen 3 Prius Technical Discussion' started by Former Member 68813, Oct 4, 2010.

  1. Former Member 68813

    Former Member 68813 Senior Member

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    I'm a new member learning to use my Prius. I like to use the EV mode in parking lots or to back up from my garage or driveway and avoid running the engine just to warm it up because it warms up quicker and efficiently while driving with engine on (gently of course).

    I had a few times when EV was cancelled due to "too high speed" and engine started while I was creeping at very slow speeds (<10 MPH). Today it happened twice. First when I was slowly driving in a flat parking lot of DOR where I got my new Prius plates and later it happened when I was slowly exiting from a parking garage DOWNHILL while braking and regenerating. The battery was almost full all the times it happened (so far it stays almost full all times). The driving distances were very short, like couple of hundreds of feet the most.

    I can understand why that would happen while driving uphill (I had that too), but flat or downhill at 10 MPH or less?

    I don't think the speed sensor is bad, because I also had EV canceled a few times exactly at 25 MPH and that is normal.

    Other than that the EV is great. My house is at the lowest point of the subdivision and if I watch my speed carefully (<25 MPH, incidentally a speed limit) I can go entire mile back home in EV and charge the battery to full state in the process by regenerative braking. By doing my average MPH jumped from 50 to 52 and I just started doing it.
     
    #1 Former Member 68813, Oct 4, 2010
  2. Skoorbmax

    Skoorbmax Senior Member

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    This is normal. Three things, AFAIK, can take you out of EV mode if you're lucky enough to get the computer to gracefully accept you into it:

    1) Accelerating too fast; if you accelerate to the right of the second large bar on the throttle slider-thingy.
    2) High speed. High speed can be 10 mph. Typically if you put EV mode in from a dead stop it will cut out once you hit 10 mph. If you get EV mode to kick in when you're going a few MPH, though, it will let you go up to 26 mph before cutting out. DO NOT QUESTION IT. You do not deserve to know why it does this. It just does, and you must accept it and be at peace with it.
    3) Battery too low.

    I have played (and I say play because that's all EV mode is, a toy) with this a lot and I still cannot always predict when EV mode will engage. For example the other day the car was totally warmed up and one bar short of full but from a dead-stop EV mode would not kick in. And it wasn't hot out, either, nor had I been driving long (but it was warmed up). I think it may just have said "not available", but in any case EV mode is like an mystic leader that demands your tribute and will always keep you guessing.

    BTW you can get EV mode to kick in when cold but NOT if the ICE has begun. The magical sequence is as follows:

    Brake > Press power to turn on car > PRESS EV RIGHT AWAY > put it into R or D. If you wait too long and the car is cold and ICE kicks in but isn't warmed up it won't let you into EV.
     
    #2 Skoorbmax, Oct 4, 2010
  3. Former Member 68813

    Former Member 68813 Senior Member

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    Yes, this is exactly what I do. At least it works great for my clumsy maneuvering in and out of my garage when there is one car in and another in the driveway. It gives me very low speed and great precision. Normal cars with ICE engines racing due to warm-in cycle make it much more difficult.
     
    #3 Former Member 68813, Oct 4, 2010
  4. ksstathead

    ksstathead Active Member

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    Turn off all climate control and other current drains. Might help with ev denied situation.

    You can regen without EV mode on your descent toward home, and do so up 45 mph engine off or unlimited speed engine spinning without fuel. Assuming into stage 3 or 4.
     
    #4 ksstathead, Oct 4, 2010
  5. Former Member 68813

    Former Member 68813 Senior Member

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    After reading the warm up stages in one of the sticky posts, it suddenly occurred to me that the today's denied EV episodes must have happened when engine cold and speed hit 10 MPH.

    Maybe I should not use EV mode on the first start and just allow the Prius to warm-up the engine like it wants to do routinely?
     
    #5 Former Member 68813, Oct 5, 2010
  6. fuzzy1

    fuzzy1 Senior Member

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    Mine also requires that the engine coolant temperature, as reported by a ScanGauge-II, be above 68F.

    If EV is available at lower temperatures, I am using the wrong recipe.
     
    #6 fuzzy1, Oct 5, 2010
  7. Former Member 68813

    Former Member 68813 Senior Member

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    I guess you are right. I still think there would be some energy benefit in EV for my descent just for the lower speed and lower friction. Watching speed below 25 MPH is a hassle though.

    So, is EV only good for very low speed (<10 MPH) maneuvering in my driveway/garage?
     
    #7 Former Member 68813, Oct 5, 2010
  8. Erikon

    Erikon Active Member

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    The engine has to be thoroughly warmed up and the battery at four or five bars, no defroster, and "usually" you can use ev at up to 25 mph! It's really a fairly useless mode the way it's configured, cause under those conditions the car will automatically be operating on electric anyways!

    The only advantage is it will allow you to accelerate harder on pure ev!
     
    #8 Erikon, Oct 5, 2010
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