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Why does my range count down using EV?

Discussion in 'Gen 3 Prius Fuel Economy' started by Rocknroad, Jul 17, 2014.

  1. Rocknroad

    Rocknroad New Member

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    I introduced myself over in the newbie section so I hope that grants me allowance to post a question.:D
    I searched, of course, but didnt get a good answer to my question. Or an answer at all.

    Ive had my P3 for a week and have really been working on getting the max MPG using tried and true techniques and Ive settled at 53mpg on average for the week.

    During my commute, there is a loooong stretch of downhill - almost 3 miles - where I never engage the ICE but I notice my range ticks off with each mile.

    Curious about this. Is the range indicated a combo of ICE and traction motor?
     
  2. bisco

    bisco cookie crumbler

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    congrats on your new pri and 53 mpg! without questions, we wouldn't be here. :) what speed are you traveling? are you talking about dte or battery indicator?
     
  3. Rocknroad

    Rocknroad New Member

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    Thanks!
    Talking about dte. Like this morning I was at 177 dte with total traction motor to the bottom of the hill and when I got there the dte was at 173.
    I never lit up the ICE. but lost 4 miles.

    The speed limit is 45 but I hit 55 or so by the bottom of the hill.:cool:
     
  4. sisharp

    sisharp Member

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    The range is using the average mpg that you have been getting. Would it make sense for that meter to be instant? Imagine when you accelerate up a hill and see your date drop like mad but then on the other side in the downhill to have the range shoot to 9999 miles till empty. It would drive you mad not knowing how many reasonable miles you have left. So.... It's an average because eventually you will use the ICE
     
  5. bisco

    bisco cookie crumbler

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    i think the ice spins up at 42 mph, but i don't think it uses any gas. the mfd may not be as accurate as a scan gauge in determining ice on/off. or perhaps the dte just counts down by miles traveled and recalculates at some later time? as you can tell, i'm just guessing!:p edit: sisharps explanation sounds good. ^^^
     
  6. Former Member 68813

    Former Member 68813 Senior Member

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    Is that counter exact enough? I rarely use it, only when driving with blinking fuel gauge and when I check it shows 0. Yet, I can pump no more than 9.5 gallons, meaning I still have hundreds of miles of range left.
     
  7. Rocknroad

    Rocknroad New Member

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    Makes sense.
    I drove the gas level down to one pip and it showed a range of 52 which aligned with my mpg average.
    Based on the sporadic way it got there though I was just curious how accurate that reading was.

    I realize there are a tonnnn of factors that go into dte but coasting down a 3 mile hill and losing 4 miles in dte got me questioning.
     
  8. sisharp

    sisharp Member

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    Rocknroad - To make it easier to understand imagine you live at the top of the hill. You drive down the hill 100 miles. So you're mpg would be infinite since you didn't use any gas. Now, you can't just stay down the hill. At some point you must get back up the hill otherwise if all the roads were downhill we would all live at the center of the earth. Soooo, on the way back home you average 20 mpg the 100 miles back home. That means you used 5 gallons of fuel. Your average mpg between your infinite downhill and your 20 mpg uphill would be 40 mpg. You went 200 miles and used 5 gallons so 40 miles per gallon average. So even though you would like your dte not to move while you are on ev it makes sense that it moves because it all averages out.
     
  9. Rocknroad

    Rocknroad New Member

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    sisharp - that's dang near my daily commute. I drive over 800 feet down to Atlanta and back up again to where I live.

    thanks!

    just a green horn getting used to this machine.
     
  10. DoubleDAZ

    DoubleDAZ Senior Member

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    It doesn't make sense unless the number being displayed is some time, distance and fuel level behind. It is mathematically impossible to increase a distance, not use any fuel and compute a lower mpg. The formula 103/x > 100/x will always be true.
     
  11. Rocknroad

    Rocknroad New Member

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    -DoubleDaz, this elicits another query - not for you to answer. How accurate are the Gen3 gas tanks. Is simply pointing down hill changing the dte because of where the fuel hits the sensor? And does it not reset when on level ground?

    it doesn't, btw. I just keep losing dte.
     
  12. DoubleDAZ

    DoubleDAZ Senior Member

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    Very good point Rocknroad.
     
  13. BackstopDC

    BackstopDC New Member

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    How would the dte react if you lived in Florida (flat roads) and you drove around all day at 41 mph (or under) with the ice kicking in about 5-10% of the time?
     
  14. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Welcome to the club. Just a couple of points to share:
    • Miles to Empty - counts down to 0 but there is still gas in the tank.
    • Using tripmeter on 'flash' - I reset a tripmeter when the tank flash begins and then track the gallons consumed by dividing the miles by the MPG. Past benchmarks show my Prius has 2.1 gallons remaining so this gives me an accurate counter to when the car will actually run out of gas. This typically gives me about 120 miles to decide when and where I'll fill-up depending upon what mileage I'm getting.
    • The Prius engine runs above 42-46 mph depending upon current state but 42 mph is a better bet. The rules governing engine running above 42 mph are not clear, yet.
    • Our NiMH traction battery gets warmer when charged so when descending, I prefer to use "B". If the car slows down too much, I shift between "N" and "B" as needed to maintain the desired speed. This minimizes 'heat pumping' the battery and heat is the enemy.
    • When ascending hills, it is best if the there is no draw on the traction battery using the energy flow display because it means the battery will need a charge (and subsequent heat) later. Using a semi-trailer truck as a pacing vehicle is an effective technique to minimize the need to climb a hill drawing traction battery power.
    GOOD LUCK!
    Bob Wilson