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ERDTT = Engine Running Due To Temperature

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by ny_rob, Mar 14, 2014.

  1. retired4999

    retired4999 Prius driver since 2005

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    15 degrees outside? here in Eau claire, Wi. This year in February our average temp was 7.7 degrees! the volt would have run all month?
     
  2. GregP507

    GregP507 Senior Member

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    In my short time as a PIP owner, I've acquired much respect for the Prius design. While I am a fiddler (love to fiddle) I wouldn't want to disable the ICE starting up. It's too important that inverters and converters be kept in a safe operating temperature range, and the ICE is programmed to do that. It's a sophisticated system, and I don't want to mess it up.
     
  3. ny_rob

    ny_rob Senior Member

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    I think the electronics (inverter, etc) are fine at low temps- it's the traction battery that needs protection.
    The PIP doesn't have active low temp protection for it's traction battery- so they run the ICE which heats the cabin which in turn heats the battery. More importantly- at low temps a cold battery can't discharge or charge at the same rate as a warm battery, so they offload some of the job of pushing the vehicle to the ICE in very low temps to protect the battery from excessive current flow in either direction.
     
  4. EVExtend

    EVExtend Junior Member

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    Doesn't the PiP run the engine whenever heat is requested, regardless of outside temperature?

    What happens when it's under 15F, is the Volt cycles its engine, so yes. It will use the engine to assist the resistive heater in heating up the coolant faster, solely to warm the cabin for passenger comfort. Once the coolant reaches a certain temperature, the engine turns off for a while until the coolant temperature decreases to the "turn on" set point again.

    It works quite well for longer trips, but it is frustrating to people for shorter commutes since they have a full battery, and unlike the Plug in Prius, they have the resistive heater to provide heat without need for the engine, strictly speaking.

    The hope is they'll eventually provide a configurable option to disable the engine assisted heating altogether, as they have many similar configurable options in the Volt. (For example, the set point can be changed between 15F and 35F; the engine assisted heating can also be set to disabled for when the vehicle is plugged in.)

    It's sort of amusing in that people become so frustrated at burning a tiny amount of gasoline to warm the cabin... but as everyone here has found out too, that electric drive is just so addicting, using zero gasoline becomes a challenge many people enjoy. :)
     
  5. retired4999

    retired4999 Prius driver since 2005

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    Yes, it starts when heat is asked for. I just don't ask for heat!
    Real short trips 2-3 miles takes me about 5-7 minutes. :)
     
  6. EVExtend

    EVExtend Junior Member

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    And that's the real annoying subtlety with the Volt... The engine starts regardless of whether or not heat is asked for, if you're below that temperature. I think this was fixed with the 2014, and all but the most dedicated EVers will usually want heat anyway, but still. :)
     
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  7. GregP507

    GregP507 Senior Member

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    It seems to me that the system is designed to save fuel, and it does it well. The engine doesn't run unless it has to, but when it starts up, I'm sure it's for a good reason. I have no desire to micromanage my PIP hybrid system.
     
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  8. 3PriusMike

    3PriusMike Prius owner since 2000, Tesla M3 2018

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    It would be nice if the PIP wouldn't start the ICE if in ECO mode and the fan speed was set to low. This way you could at least turn on the system and adjust the temp and/or get any heat out of the system without forcing the ICE to come one. Same thing for the Volt and other plugins...
    I guess the car makers think they would get too many service complaints of no heat.

    Mike
     
  9. GregP507

    GregP507 Senior Member

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    I don't have much doubt that any damage traced back to disabling the engine-start sequence would void the warranty, not to mention the expense.
     
  10. 3PriusMike

    3PriusMike Prius owner since 2000, Tesla M3 2018

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    I don't think anyone is suggesting making a mod to the car...this is a suggestion for Toyota and other car makers for future models.

    Mike
     
  11. GregP507

    GregP507 Senior Member

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    Based on all the developments that Toyota has made in the Prius to save fuel in every conceivable way, don't you think that they have already done their best to minimize the run-time of the combustion engine?

    A good example is the way they installed a heat-exchanger in the exhaust system to shorten the time it takes to warm up the engine coolant.
     
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  12. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Saving fuel is actually the secondary objective. The primary is to reduce emission -- not just the exhaust but also upstream (vehicle production as well as fuel production).

    If the engine is running when you think it should not, most likely it is done to keep the emission low.
     
  13. GregP507

    GregP507 Senior Member

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    That actually doesn't make sense. Emissions are a fixed target, while fuel economy is a moving target; whereby the Prius commands a premium price for its superior fuel economy.
     
  14. 3PriusMike

    3PriusMike Prius owner since 2000, Tesla M3 2018

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    Actually no. Here is just one example. You have a full charge and are going less than that distance. It is a cool sunny day and the car is a bit hot and you want the fan on...not the A/C, not the heat, just the fan to bring in outside air. You turn on the fan, but since the last time you had the fan on (last night) you had the heat on with temp=Hi. You can't know this from looking because the temp doesn't show until after you turn on the fan. This triggers the ICE to come on because you can't press the temp down arrow to go from Hi to Lo faster than the car decodes the ICE needs to run. There was absolutely no reason to have the ICE on, the entire warmup cycle was essentially wasted. And about the only way to get around this is to turn on just the accessory mode, turn on the fan, change the temp, turn the car on via break pedal and power switch. But of course you have to remember to do all this before you drive off.

    There are probably other examples.

    The car is great, but not perfect.

    Mike
     
  15. GregP507

    GregP507 Senior Member

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    The ICE may have to run for a variety of other reasons besides running the heater. The aux battery may be low or the computer may need to equalize temperatures in the inverter/converter
     
  16. 3PriusMike

    3PriusMike Prius owner since 2000, Tesla M3 2018

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    Sure...but not in this case. Try it a few times. It is just as I say.


    Mike
     
  17. Lourun

    Lourun Member

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    I agree happens to me quite a lot.
     
  18. usbseawolf2000

    usbseawolf2000 HSD PhD

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    Nope. Emission and fuel economy are trade-offs. For example, HSD would not shutdown the ICE until catalytic converter is certain temp. That's using extra gas for the purpose of emission.
     
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  19. GregP507

    GregP507 Senior Member

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    Sorry, that makes even less sense to me.
     
  20. ny_rob

    ny_rob Senior Member

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    It makes sense if low emissions are a priority vs fuel economy...;)

    I've also had my ICE run (as in Mike's example above) because I forgot to turn the temp control down to LOW before shutting the car off on my last trip.... it's very frustrating.
    Toyota could have built a 30 second delay in to the system to give you time to turn down the temp setting after ignition.