Parking lot with A/C, 94% SOC, ICE turns on

Discussion in 'Prime Technical Discussion' started by PiPLosAngeles, Jun 24, 2020.

  1. PiPLosAngeles

    PiPLosAngeles Active Member

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    While waiting in the car for someone to run some errands I sat with the A/C running. The car was in a parking structure, so shaded. Outside temp was 74, A/C set at 72 AUTO and ECO. It was taking about 7 minutes to run the SoC down 1%. After SoC drops to 94% ICE kicks on and charges the car to 96% and then shuts off. When the car reaches 93% we repeat the cycle. Down three, up two. Did this for an hour and a half.

    Does anybody know the logic of this behavior?
     
  2. Raytheeagle

    Raytheeagle Senior Member

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    I take it you were in HV mode:whistle:?

    When the power went out here many months back, I was in EV mode and the Prime was "ready" and sat in our driveway working out of the Prime for 2 hours and no issues with the engine kicking on;).

    This was using an inverter (to run my laptop off the auxiliary port) and the fan as the temps outside were in the 60's, but I still used about 10-15% of the battery, from what I remember:).

    Not sure of the answer, but at least one comparable experience from a timing perspective with a different result (y).
     
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  3. jerrymildred

    jerrymildred Senior Member

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    +1, @Raytheeagle.

    If you're in HV, the car will want to maintain approximately the same state of charge as when you put it in HV. But in EV, it will run the battery right on down to the HV only range before starting the ICE.

    That's assuming no pushing of defrost button or call for heat in really cold weather, which sounds like a safe assumption in this case. ;)
     
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  4. Salamander_King

    Salamander_King Senior Member

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    Never did it for a long time, but I don't think I have every had engine come on while on EV mode (meaning traction battery had SoC left). I have done more of this with the heat on, but not so much with cool (A/C) on.
     
  5. PiPLosAngeles

    PiPLosAngeles Active Member

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  6. fotomoto

    fotomoto Senior Member

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    What operating mode was the car in?

    I don't have a Prime but it's been my experience with other hybrids that when the temps are this close, the heater is often used to provide balance. Air-conditioning is either on or off; when on it's providing sub-60 degree air so something needs to warm it up to 72f at the vent because the ambient isn't very warm (74f). So I'm suggesting the car "decided" to run the ICE to provide warm coolant instead of using electric heat. Just a guess.

    If you can repeat, try taking it out of ECO and see the behavior returns.
     
  7. PiPLosAngeles

    PiPLosAngeles Active Member

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    That was my initial suspicion, but the Prime doesn't use the ICE for heat.

    There's a variable missing because this only happens sometimes even in ECO. I'm working on figuring it out, but hoped maybe someone else had already done the dirty work (or read it in the manual).
     
  8. fotomoto

    fotomoto Senior Member

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    Yeah, I know it has the heat pump but maybe ECO thinks the ICE is more efficient in this case (however unlikely). Weird.

    @john1701a
     
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  9. Mendel Leisk

    Mendel Leisk Senior Member

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    Trying...to...restrain...myself...
     
  10. route246

    route246 Member

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    It doesn't?
     
  11. fotomoto

    fotomoto Senior Member

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    Like a lot of things in life, it's complicated. Yes, the ICE is used for heating but the heat pump is the primary source and mostly by itself (especially in L.A.) Heat pumps don't work well in really cold temps so the ICE takes over heating duties then.
     
  12. route246

    route246 Member

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    From what I read the heater is using coolant from the ICE exclusively for heating. Are you saying that the heat pump is capable of reversing thermal energy? I was just questioning the statement, "Prime doesn't use the ICE for heat" as if the exclusive source of heat is reversing.
     
  13. john1701a

    john1701a Prius Guru

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    Where was this? Most likely, you were reading outdated information. Though, there is a possibility of intentionality being misled... hence it being nice to find there originating source.

    Anywho, both cabin & battery heating are primarily electric. Once you run out of plug-supplied electricity or the outside temperature drops below 15°F, the engine will join in. So, most of my commutes even here in the north, are all EV.
     
  14. john1701a

    john1701a Prius Guru

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    My guess is that would be battery temperature.
     
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  15. jerrymildred

    jerrymildred Senior Member

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    Yeah, a hot (or cold) traction battery would start the ICE. But it doesn't sound like the weather was hot or cold enough for that.
     
  16. PiPLosAngeles

    PiPLosAngeles Active Member

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    Even more strange is that the ICE hadn't even run in over 24 hours. The drive to the place was entirely EV. I charged at a nearby charger, drove to the structure, and then sat there. The ICE didn't even come on until after being parked for over 20 minutes.

    This isn't an isolated incident. When it does happen the A/C is invariably running, and the car doesn't have to be parked. I've had it come on in EV mode with >75% SOC while driving in slow traffic and even at traffic lights.
     
  17. fotomoto

    fotomoto Senior Member

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    There it is.

    Pack got warm during the drive, then warmer during the L2 charge, and then hot will being discharged in the parking garage. ICE came on to cool it.

    I use a ScanGauge II to monitor the temp of the forced-air-cooled pack in my Energi. Charging a hot battery really raises the BTU's and accelerates capacity loss.
     
    #17 fotomoto, Jun 24, 2020
    Last edited: Jun 24, 2020
  18. PiPLosAngeles

    PiPLosAngeles Active Member

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    Why would it keep turning on and off for 90 minutes 2 hours after the charge complete. That seems like a horribly retarded strategy for cooling a battery pack that's only delivering ~1.5A. I'm curious how the ICE cools the battery pack.
     
  19. Salamander_King

    Salamander_King Senior Member

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    Maybe it is not so mach of the "strategy for cooling a battery pack", but is just a program in ECU which at certain battery temp ICE would kick in to relieve the battery pack of the duty. If the battery pack temperature is hovering up and down of this threshold temperature, you will see the ICE kicking in and off periodically as you experienced. Although this is only speculation in my part. As said, I have never encountered ICE coming on and off for 90 min on EV mode.
     
  20. john1701a

    john1701a Prius Guru

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    Once the system determines the ICE may be needed, it will maintain minimum operating temperature for emission cleansing. In other words, the ICE will cycle on & off. So, it's temperature would need to be monitored as well.
     
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