How to Reduce MPG loss Because of A/C Use

Discussion in 'Gen 2 Prius Fuel Economy' started by F8L, Sep 11, 2011.

  1. dbcassidy

    dbcassidy Toyota Hybrid Nation, 8 Million Strong

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    What are you saying with the above remark? Not the threshold part, but the second sentence in your statement?

    DBCassidy
     
  2. F8L

    F8L Protecting Habitat & AG Lands

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    Tall & Thin people dissipate heat easier.
     
  3. 2009Prius

    2009Prius A Wimpy DIYer

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  4. Jon Hagen

    Jon Hagen Active Member

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  5. dorunron

    dorunron Senior Member

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    Excellent post Jon and video to boot. I too agree that using the A/C will lower the MPG some in the Prius. However as F8L has pointed out in this string, creature comfort and traction battery comfort are important. It is the general consensus that the hotter the traction battery gets, the shorter the lifespan of said battery will be. I am saying this for those who are not as familiar with the Prius as you and I are. Most here on PC pretty much know their way around the Prius. However there are new comers every day who are newbies, just as all of us were at some point in our lives. It is for their benefit that I wrote the above words about the temperature of the traction battery.

    Again, great post and good documentation.

    Ron (dorunron)
     
  6. SageBrush

    SageBrush Senior Member

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    No doubt, heat is the enemy of electronics and batteries, but a couple situations are particularly bad: One, is parking the car with a full battery in the heat.

    The other scenario I avoid is turning the car into an oven by parking in the full sun with windows closed.
     
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  7. NinnJinn

    NinnJinn Member

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    Last week I took a small trip in my generation ll and due to the occupants had to run the air conditioning ambient temp about 87 degrees and humidity was running about 40% for 150 miles on the interstate running 75 miles per hour an air conditioner on full blast I got 34.2 mpg on mfd. On the trip back without occupancy I ran the same route back home with the a_c off and windows down and I reset the mfd before I left to come home and averaged 41.8 have yokohama tires with about 15k miles on them. 44psi front 42 rear.
     
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  8. Mendel Leisk

    Mendel Leisk Lapsed Cargo Cultist

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    I suspect the need to run AC to protect the battery is overblown, and AC does impact mileage, as attested above. Long drives, vacations, we'll turn it on, but for shorter runs we'll just run the windows down and enjoy the fresh air.

    When turning it on I'll hit Auto, then AC, then run the temperature up, until the fan speed subsides a little. As it gets working, and the fan speed drops, I'll drop the temperature, never so much that the fan races. I'll typically settle around 23~24 centigrade (73~75 Fahrenheit).
     
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  9. SageBrush

    SageBrush Senior Member

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    Yep.

    For long drives I use AC as much for comfort as safety: a warm environment makes me sleepy.
    If I start the drive with the interior a higher temperature than ambient I drive with windows open for 5 - 10 minutes. It only takes a fraction of that time to bring the cabin air to ambient temperature, but much longer to pull some heat out of the plastics and metals. My rule of thumb is that if the dash is only warm and not hot, it is time for AC. I pick 'auto' and set the temp to somewhere between 75 and 78. Over long drives at ~ 65 mph and in my high desert climate of low humidity and temps in 90sF, the AC use results in about a 2% mpg hit.
     
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  10. frodoz737

    frodoz737 Top Wrench

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    To each his own, but I'll use my sweat to cool off while working, not driving.
     
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  11. SageBrush

    SageBrush Senior Member

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    My wife has recently starting bicycling again and has been surprised that she does not feels anywhere near as hot outside as she is used to. She is Physics averse, so I just said "bicycling is like having a fan wherever you go!"
     
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  12. Toppcat

    Toppcat Member

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    Something everyone fail to address! Driving down the road the sun is beating heating up that big black Prius dash, anyone ever notice how hot that plastic dash gets producing heat while the ac is try to cool the cabin. Like having a ac and heater going at the same time! Installing a cloth type dash mat with window tints will reduce interior heat weather parked or driving down the road!
     
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  13. stockdaddy

    stockdaddy Member

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    Got 50mpg on day around 82F hot sunny day when I set my AC to auto 76F.

    I thought of putting product like 3M Crystalline window tint in my car.
     
  14. CooCooCaChoo

    CooCooCaChoo Member

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    I don't know about you guys, but I have the AC on auto all the time and still get 50-55 mpgs. I run 40/38 psi on nearly worn out tires that are going to be replaced soon.

    On a recent trip to Bodega Bay, got about 52 mpgs doing 65/speed limit. AC on auto during the day, low/low+1 blower setting at night.

    On another recent trip to San Francisco, got about 55 mpgs. Same speed. Same AC settings.
     
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