EV-Auto Mode: Warm-Up Cycle?

Discussion in 'Prime Main Forum (2017-Current)' started by mr88cet, Apr 4, 2017.

  1. RobertZ

    RobertZ Member

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    This is old discussion but my issue may be related. Prius Prime since 2017 December. I have 35 mile commute to work one way so with the full charge I try to use about 15 miles of pure EV each way. Normally I drive on HV mode once I enter highway and about after 10 miles or so (or when there is a lot of slow down) I switch to EV-Auto. What I am observing is that it switches to EV-Auto but ICE remains on for good 2-3 miles. It does use battery in that mode as I can see the range go down. Even if I force switch to EV mode (Not auto) it still keeps engine on. In the evening drive (when temps are above 35) I notice it shuts off ICE fairly quickly if I switch to EV or EV-auto... I live in New England so mornings in winter can be cold.
     
  2. bisco

    bisco cookie crumbler

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    Makes sense. The colder it is, the longer the warm up cycle.

    Once you switch out of ev, the engine has to finish the cycle, you can’t stop it yourself, without pulling over, shutting down and restarting
     
  3. KP7

    KP7 Member

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    Correct. I believe the cold weather warm up cycle is 3 min and it pulls from the traction battery during that time to keep a very low load on the ICE. Once up to temp the ICE will cycle on and off as you'd expect.
     
  4. RobertZ

    RobertZ Member

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    OK looks like expected behavior, I was just surprised that after 5-8 miles of driving engine would be warm enough to shut down when I switch to EV or EV-auto.
     
  5. m8547

    m8547 Senior Member

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    If you have the heat on, and if the engine is already warm, it will run the engine much more than it would otherwise need to. If the engine is cold and you have battery power it will use the heat pump. In a regular car the heat is "free", but these cars are so efficient that there isn't even enough waste heat to use to heat the cabin.

    Also, once the engine is warm EV auto and sometimes EV mode seems to run the engine sometimes when climbing hills.

    It will also run the engine in EV mode for various reasons like cold battery, slightly cold battery and cruise control, hot battery, long hill, b mode, defroster, etc.
     
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