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why the engine keep running but no charging and no driving?

Discussion in 'Gen II Prius Fuel Economy' started by georgezheng, Dec 8, 2011.

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  1. georgezheng

    georgezheng New Member

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    why the engine keep running but no charging and no driving? the car was down hill, the battery was fully charged (green), I did not accelerate ( my foot was not on the paddle), but the engine sometimes keep running with a very low gas consumption. this become more often in winter, even when car stopped. I would like to know is this normal for Prius or there is any I can do to improve this?
  2. qbee42

    qbee42 My other car is a boat

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    The Prius will run the engine to keep warm. You can fix this by driving in a warmer climate.

    Tom
    1 person likes this.
  3. cwerdna

    cwerdna Senior Member

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    As for the first case, see http://priuschat.com/forums/gen-ii-...936-engine-rpm-high-car-not-accelerating.html. You'll hit that if SoC of the HV battery gets too high and you're going downhill. It'll look like the battery is full (all green) on the MFD and soc on Scangauge will show some value above 75%. I've never seen the HV higher than 81% or so soc per Scangauge. You'll definitely see all bars filled (w/green) if you're at 80% soc.

    To prevent the ICE from running to provide cabin heat, see the stuff at the bottom of http://priuschat.com/forums/gen-iii...mileage-gets-worse-in-winter.html#post1411488.
  4. richard schumacher

    richard schumacher shortbus driver

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    Wear a heavy coat and turn off the air system.
  5. danboy

    danboy Junior Member

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    You sound like a candidate for grill blocking and possibly block heating. I went ahead and blocked mine a few weeks back and it helps.
  6. googrx

    googrx New Member

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    Nonsense. The Prius climate system is independent of the gasoline engine and the electric engine. There are no belts that related to the gas engine. It is all electric.
    The heater may consume as much energy as the AC. It is possible you have a recharging problem on the main battery.
  7. cwerdna

    cwerdna Senior Member

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    Says the guy who wouldn't test his 12 volt battery and kept insisting it was fine... until it read 4.9 volts. (http://priuschat.com/forums/gen-ii-...bleshooting/101767-problem-w-my-05-prius.html)

    The ICE on HSD based hybrids will run to provide requested cabin heat if the ICE is too cold. Please read the bottom of http://priuschat.com/forums/gen-iii...mileage-gets-worse-in-winter.html#post1411488. I've confirmed this behavior on my Gen 2, on a Gen 3, on a Lexus HS 250h (that I won a week free test drive of), Camry Hybrid and Altima Hybrid.

    (On Gen 2, if coolant temp is <=145F and you set the heat to high and fan to any position above OFF, the ICE WILL run to provide requested cabin heat. If the coolant temp is somewhere between 110F and 145F, the moment you turn the fan to off, the ICE stops. Turn fan w/heat at high, ICE starts back up.)

    If you use the AC while stopped, it will run the HV battery low enough to the point where the ICE needs to fire up to charge it back up.

    The Gen 1 and Gen 2 Priuses DO have "drive" belts and Gen 1's AC compressor is driven by a belt, but that's totally separate from this discussion.
  8. qbee42

    qbee42 My other car is a boat

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    Speaking of nonsense. :rolleyes: The above post is a prime example. Cabin heat in all Prius comes from the engine coolant, which is supplemented in special circumstances by small electric heaters (PTC heaters). Heat from both sources reduces fuel economy. Heat from the engine requires fuel to replace the lost engine heat. Heat from the electric heaters requires fuel to replace the lost charge from the HV battery. Either way you burn fuel to make cabin heat.

    There is one narrow set of conditions where cabin heat is essentially free. This occurs when the ambient temperature and driving conditions are such that the ICE must dump heat through the radiator. Given the efficiency of the Prius, this almost never happens during cold weather when you need cabin heat, although it often happens with conventional cars.

    Tom
  9. paprius4030

    paprius4030 My first Prius

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    At LAST... a reason to move to Florida!:D
  10. danboy

    danboy Junior Member

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    Said with such conviction, now only if it were true.
  11. uart

    uart Senior Member

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    Yep I can vouch for the fact that the heater can cause the engine to continue to idle. It's summer here in Australia and definitely no cabin heat is necessary, yet just last week one morning I couldn't figure out why my Prius was suddenly not cutting out the ICE after the usual warmup period.

    It had me totally confounded, the AC was off and I was just running the fan for some fresh air, so why the engine continuing to run? Then I notice that my wife had used the A/C the previous day (for cooling) and had set it to a fairly high temperature of about 75F (which was still colder than the outside temperature of course). Now I wasn't using the AC but since it was now morning and cooler than 75F then it was trying it's best to warm the air, and yep that meant running the ICE where normally it wouldn't be needed. As soon as I turned the temperature setting down to "max cold" (which is the only real way to turn the heater off) then the engine started to cut out as expected.
  12. LS5099

    LS5099 Junior Member

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    I also read somewhere on the forum that after a long downhill run and the regen mode overcharges the battery, the electric motor will spin the ICE to drain off some of the electricity. I believe I have experienced this on a number of occasions myself when stopping at a traffic light after a long down hill run. THe ICE runs, then stops, then starts again for two or three cycles and about 30 seconds. Is this what is happening?
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