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on hunkering, Gen 3 style

Discussion in 'Gen 3 Prius Main Forum' started by ChapmanF, Jan 1, 2018.

  1. ChapmanF

    ChapmanF Senior Member

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    A late response to this question, but the answer was kind of just given in another thread:

    Question about fuel usage to heat Gen 4 during a snowpoclase like on I 95 | PriusChat

    I guess the question was interesting to me because of my own experience. When I was a kid, we were driving back from Thanksgiving with family in Ohio, and became participants in the Blizzard of 1974.

    We spent a few hours among all the immovable cars getting slowly buried at the side of the interstate, then got dug out by road workers in heavy equipment and taken to a local high school, where we spent the rest of the weekend on cots in the gym. Then we were taken back to our car and finished the trip home without further incident.

    I suppose if a person has had that experience, then "I wonder how effectively I can hunker in this car" is just a question that pretty much asks itself, and to a person who hasn't, it may seem like an odd question.
     
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  2. priusrecon

    priusrecon Member

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    Found this post interesting, and just for s&g's thought I'd throw in some Gen 2 numbers, since 1's & 4's were also mentioned.

    I had simply hit the defrost button on the steering wheel with it set to 75 deg. Outside it was about 20 deg F.

    While just warming the coolant, got about 0.25 GPH. When topping the battery, it kicked up to about 0.45 - 0.50 GPH.
    I didn't stopwatch the duty cycle, but offhand it appeared to be around 50/50.

    This was while waiting in a long drivethru line last night, lights off & with the radio blaring.
     
  3. FreeFly

    FreeFly New Member

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    A video from Mountain Springs Adventures:
    'How "climate control" of a Toyota Prius (and other hybrid cars) works for camping & sleeping!'
    ^I can't post links yet since this is my first post, but there's the title

    It shows his setup for heating. He says he keeps his heat setting at 65 F, and uses a small 250 watt AC heater connected to an inverter. He claims it increases the time between starts, though he doesn't provide specific benchmarks, so it may be possible that one can increase hunkering times further.

    It may help in lieu of a "hunker extender", but I might try to build an extender if I get the chance later. It would require a bit of work, and programming a micro-controller.

    I need to try a heater to be certain, but some of the supposed pros are that it would increase efficiency and airflow. It could also be used along with heated blankets.

    A con with his specific setup is that his heater is connected to an inverter. If there's about a 10% efficiency hit from the conversion, a DC heater may be more efficient, and you wouldn't have to fiddle with turning an inverter on and off whenever you weren't using it, although some inverters have remote switches. If I try it, I think I'll get a DC heater at a comparable wattage that runs on the 12V car plug.
     
  4. CR94

    CR94 Senior Member

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    That's interesting, because I spent about 24 hours stationary between tunnels on the Pennsylvania Turnpike during and after that storm. We weren't physically stuck in the snow directly, but the heavy holiday traffic came to a standstill because trucks couldn't make the hills, and plows couldn't keep up with the snowfall rate (or couldn't get through).

    Some people ran out of fuel idling their engines to keep warm. They had the excuse that, due to the storm, electric power (hence gasoline pumps) was out in the last town before they got on the Turnpike.

    Many years later on a bus trip, my mother met a bus driver who told of getting stuck on the Turnpike in a bus by the same incident.
     
    #24 CR94, Nov 15, 2022
    Last edited: Nov 15, 2022
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  5. CR94

    CR94 Senior Member

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    The losses in the inverter would simply become heat, so wouldn't be wasted, if heat is all you're trying to get from it. Still, using an inverter would be a pointless complication if a 12-volt heater is available.
     
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  6. CR94

    CR94 Senior Member

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  7. ChapmanF

    ChapmanF Senior Member

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    If you already had a hunker extender, I don't think adding more electric heat would improve anything further. The hunker extender already gives you a cycle period determined by how often the battery needs charging, and adding more electrical load will make the battery need charging more often.

    For hunkering purposes, I think the most promise will be in heated blankets (or similar things like heated vests, booties, mittens, etc.). Things that put the heat on you, rather than trying to heat the whole space.

    That said, because the hunker extender means a lot of time with the car's fan off, a small plain fan might not be unwelcome sometimes, just to keep the air distributed better.

    You wouldn't be able to power a comparable-wattage (250 W) one from the car plug; those outlets are limited to 120 watts. Larger, you'd have to hardwire.

    Any electric heater that is bare-bones enough will work as well on DC (of the same voltage as the RMS AC voltage)—if there are going to be problems, they'll be if it's not bare-bones enough, and has some kind of fancy control board that cares what kind of power it gets, not the heat element itself. For example, you could find some UK 240 V space heater and wire it to the traction battery without an inverter, as the voltage would be in the right ballpark. I am not suggesting that as a desirable or sane thing to do, and again, it would just shorten cycle times. But the heater wouldn't mind.
     
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