EV Mode Cold Weather

Discussion in 'Prime Fuel Economy & EV Range' started by TRHaley, Dec 21, 2017.

  1. CraigM

    CraigM Active Member

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    . Better not adjust our power seat or use our turn signals!
     
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  2. Tideland Prius

    Tideland Prius Moderator of the North
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    Nope. The Prime's vapour-injected heat pump is super efficient by today's standards. Granted, I'm not seeing the temperatures that the eastern half of the continent experienced at the end of January. 20.5°C, ECO Heat/Cool on and Automatic S-Flow (which is usually driver priority) results in a comfortable cabin and long range (more than 25 miles/40 kilometres). Outside temps are near 0°C on average (higher during the day, lower overnight)

    No different from gasoline cars - it's just that so much goes to waste heat, it doesn't really factor in.

    Reminds me of the people who turn off DRLs to save energy or leave the wipers in INT instead of LO. Honestly, the reduced safety factor isn't worth the pennies saved.

    @Skylis A wrote up a table with the various energy uses on the Prime. It's worth looking over.

    Estimated EV penalties for various heating cooling and lights | PriusChat
     
  3. m8547

    m8547 Active Member

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    I drove to work without the heat on today to keep the engine from coming on. It was around 9 degrees F. And I often drive without the heat to extend my range. The heat pump is really efficient, but still a big power consumer, and not so efficient when it's near the minimum temperature (11-14 F). The air conditioning is surprisingly efficient, since it has less temperature gradient than the heat pump. One time the car showed 80mpg on a 40 mile drive in HV mode with the AC on (and the EV range used up). I did the same drive another time and saw 77mpg. It is slightly downhill, but descending 600 feet over 40 miles seems negligible.

    When it's warm enough for the heat pump to work efficiently (above freezing in my experience), it's not cold enough to need to turn on the heat anyway.
     
  4. john1701a

    john1701a Prius Guru

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    Works just fine for us with the temperature in the 20's. Today, it was just 12°F today and I didn't plug in at work (nasty snow storm). The drive home in EV was comfortable... so, that begs the question: What do you wear while driving?
     
  5. Bill Norton

    Bill Norton Senior Member

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    "S-Flow"? Doesn't sound nice. :eek: They need a better name,, whatever that function is.;)

    "long range"
    ? I don't think so... 25 mi is the EPA rating. We are talking about the hit really cold weather takes on EV range. I guess 25 mi may be in the middle of the pack these days for PHEV's.

    But it's always 'Limited' EV driving, not True EV driving.
    You're always one button press, 1/4" of throttle pedal, or one MPH from having that ice cold smelly gasser wake up and start making power to 'assist' when the EV functions are not capable.
     
  6. m8547

    m8547 Active Member

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    Yesterday, a down jacket, hat, and ski gloves. It wasn't bad with the seat heater on. If it's above freezing probably just a jacket.

    If it's below 20 and I use the heat I'll usually make it to work with between 1-15% battery remaining. Otherwise I'll usually have about 25% remaining. So I guess I could use the heat as long as I don't make any stops on the way to work. If I'm using the heat it's usually the defroster (feet and windshield setting) because the windshield is frosty, which probably uses more power than just heat.
     
  7. GrandRapidsPrime

    GrandRapidsPrime New Member

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    I drove home from work yesterday and made it home in EV mode for the first time. The trick: no heater indeed. It was 42F so it wasn't too bad.
    Enthused by this behavior I did this on my way into work this morning. It was 18F and the ride was quite refreshing with no hat and no gloves :)
     
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  8. Salamander_King

    Salamander_King Senior Member

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    If there is no need for the defroster, I drive without heat most of the time, that is if I am driving by myself. My wife will not let me do that.:(
     
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  9. Bill Norton

    Bill Norton Senior Member

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    So much suffering,,,, for what cause? No gas usage?

    You know you still have to change the oil routinely regardless of your amount of suffering?
    Do you factor that into your "cost savings"?
     
  10. john1701a

    john1701a Prius Guru

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    You are missing the point. Reducing gas consumption as much as possible is for the sake of reducing emissions as much as possible.

    Are you so blinded by the purity of EV that you cannot see the benefit of that choice?

    Many people are quite willing to spend money to be greener, but don't have the option of eliminating gas entirely.
     
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  11. Salamander_King

    Salamander_King Senior Member

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    Well, to be honest, it is no suffering for me. I do enjoy the cold. If my wife let me, I will turn off the oil burning boiler for the heat in our house. That said, most of the times when I am driving with someone, I set my AC at 70F AUTO, which is uncomfortably warm for me sometimes. In addition, our cost of electricity is higher than the national average, at the current gas price, it cost more to drive EV than HV. Saving is not for me, it's for the world we live in.
     
  12. Bill Norton

    Bill Norton Senior Member

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    That's exactly the drum I'm beating, john.
    Reducing Total Cost of Ownership is a equally important to some.

    And don't forget useless oil consumption with unneeded oil changes on a PHEV with very few miles on the gasser.
    Not all PHEV's are so Lo-Tech.o_O
     
  13. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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    I'm confused - we've been running our prime (in Chicagoland lately) in all this cold weather with a 5 mile roundtrip without the engine coming on. How are you in HV mode automatically?
     
  14. john1701a

    john1701a Prius Guru

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    No, that is not. You are pushing the absolute, eliminating it entirely. That's profoundly different from reduction.

    Starting with a battery temperature under freezing will do it. Keeping plugged in eliminates that, even in extreme cold.
     
    #74 john1701a, Feb 10, 2019
    Last edited by a moderator: Feb 11, 2019
  15. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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    That explains it since we keep it on the charger. Didn't realize that.
     
  16. Salamander_King

    Salamander_King Senior Member

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    Are you running with AC(heat) off? If you have the heat on and the ambient temp is below ~14F, my PRIME will turn ICE on immediately upon starting.
     
  17. fuzzy1

    fuzzy1 Senior Member

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    That descent rate isn't negligible for a Prius. From my simple rule of thumb for a 50 mpg Gen3, that descent is worth an 8% boost in observed MPG. In more ideal conditions where my Gen3 could do 60 mpg on the flats, that descent is worth a 10% boost.

    Since your Prime is even more efficient than a Gen3, that descent should produce an even larger apparent MPG boost.
     
  18. a_gray_prius

    a_gray_prius Rare Non-Old-Blowhard Priuschat Member

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    Yes, heat off pretty much all the time. If I turn it on the windows will fog up. I have turned it on a few times during said ~5mi roundtrip and haven't had the engine come on.
     
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  19. Bill Norton

    Bill Norton Senior Member

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    No, that is not. I believe I'm not 'pushing', but pointing out that there are some PHEV's that operate as Pure EV's until the battery pack is depleted to the Hybrid Buffer.That's a good thing, no?

    I had one and only did oil changes once every 2 years! And it was a decent Road Trip car also, when needed!!

    But alas, it's true, I sold it and bought a car that "absolute, eliminating it entirely" [gas].
    And it is NOT a Road Trip car. I guess that makes it "profoundly different", but in a good way, no?;)
    However, do you want to know what I spent on Fuel and Maintenance during my 4 yrs of ownership?
    (Hint: Free public charging for +9 months a year and Zero on routine maintenance @ 62k miles! Tires. I bought tires bc this FAST little S-box is a hoot to drive!)

    Face it, the PiP was a patch for the Gen3 to do some EV tricks.
    The Prime is a patch to the Gen4 and is much better at some things.
    The next Gen Prime will finally operate as a True EV, if, and when, toyota gets all in on the Li-Ion game and stops patching in bigger packs in the back of the cabin of their existing hybrid.
     
  20. DavidA

    DavidA Prius owner since July 2009

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    The car sits outside. If it has been less that 12F all night (and it was for 4 days last week), it will start in HV mode and won't warm up enough on my 1.4 mile commute to work to kick into EV mode. I don't leave it plugged in all night because it is parked a couple feet from the street.

    Alternately, it might be 25 degrees outside, but the night time temps could have been, say, 5 degrees F. The traction pack temps might still be too cold for the car to start in EV. Pretty sure there's a thermistor somewhere in/near the battery pack to report temperatures to the computer. Probably not the same circuitry that reports outside temps to the MID/main display screen.

    If... I could keep it in a heated garage, or plugged in before I go off to work without eyes on it, then yes.

    Now, that said, it does surprise me every now and then that if it is 8F out and the traction pack is 2/3 or more charged, the ICE might not start at all, even if the rear window defroster AND the front heat pump defrost/heat is also on.

    None of this really bothers me. Last winter I might have been in forced HV mode about 10 days total. This winter is shaping up to nearly the same.
     
    #80 DavidA, Feb 13, 2019
    Last edited: Feb 13, 2019
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