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The car's on, but nobody's home...

Discussion in 'Gen II Prius Main Forum' started by ChrisHenry, Oct 19, 2007.

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  1. ChrisHenry

    ChrisHenry New Member

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    Not sure why this text didn't make it when I posted this earlier, so I'll try again...
    -------------------------
    I've got a daily "commute" of about 8 miles that's mostly on surface streets and consists of two stops that both require me to get out of the car (dropping my son off at preschool and getting my morning Jamba).

    After reading this forum a bit, I realized that the worst mileage period is right after starting the car, which is a bit of a drag since each leg of my trip each morning is only a couple of miles long. One morning, I got the hairbrained idea to not turn the car off at each of my stops, but to turn of the MFD, the climate system, and the stereo and kind of leave the car on in "stealth" mode.

    Of course, this practice seems unsafe (especially from my insurance agent's point of view) to me. I take my keys with me when I leave the car, and it give me the three beeps saying, "hello.... you forgot to turn me off..."

    Does anyone know if the car will drive if left turned on, but with the smart key not in the vehicle?

    Thanks.
  2. skandale

    skandale New Member

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    The car will work as normal (except for the 3 beeps each time a door is closed) until the car is powered off. Then the fob will be needed to start the car again.

    The car only needs the fob to power on, not to work after that. I'm not sure how it is to lock the car without the fob, so I don't know if a car thief will be able to lock the car if he/she dumps it.

    But as long as the Prius is standing in "battery mode", I don't think you save much. Your stops are probably to short. The real FE hit is when the car only warms up a little, then is stopped long enough for the ICE to cool down again and the have to warm up again.


    -Stein
  3. RobH

    RobH Senior Member

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    Yes, it will drive normally without the key. The absence of the key will not be important until the next time someone (you?) tries to turn it on again.

    Set the parking brake, press park, and lock the door with the mechanical key. Leaving it on is essentially the same as leaving the key as far as stealing the car is concerned.

    PS... The air conditioning/heater will continue to run. Nice!
  4. efusco

    efusco Troll Slayer Staff Member

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    1) As above the car will drive normally.
    2) Depending upon the length of your stops it probably does save a bit of energy/gas to leave the car on. We had a discussion at Priusonline recently on this. While it's pretty darn difficult to determine exactly how much more fuel you use going through the quick warm-up cycle vs the normal pre-warmed cycle for the same distance traveled (also not an easy distance to determine). In any case, with all the accessories turned off, as you describe, you're probably only seeing about 1-1.2 amp drain during your 'away time'.

    A very rough guess would be that a stop of no longer than 5-10 minutes and you're clearly saving energy by avoiding the mandatory warm-up and leaving the car on.
  5. JimboK

    JimboK One owner, low mileage

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    Can-View (an aftermarket instrument some of us have in the Prius) shows that the ICE draws about 7 kW during its startup phase, which lasts about 30 seconds or so when already warmed up. With the car on and sitting still, with all accessories off, there is an electrical draw of about 0.1 kW. Now, it's not as simple as saying you can sit still with the car on for 35 (7 ÷ 0.1) minutes; there will be conversion losses from the ICE running to replenish the battery charge. Still, it seems clear to me that you can come out ahead by sitting with the car on for several minutes instead of powering off and back on, at least the 5-10 minutes that Efusco proposes. I do this when it can be done safely, with 10 minutes as my threshold.
  6. hycamguy07

    hycamguy07 New Member

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    Hmmm, Ive tried this... You have to leave the fob in the socket and pull out the little key to lock the doors... ;)

    However I would also check local laws regarding you leaving your car running and unattended... In Florida that = a ticket..

    FS.316.1975 Unattended motor vehicle.--

    (1) A person driving or in charge of any motor vehicle may not permit it to stand unattended without first stopping the engine, locking the ignition, and removing the key. A vehicle may not be permitted to stand unattended upon any perceptible grade without stopping the engine and effectively setting the brake thereon and turning the front wheels to the curb or side of the street. A violation of this section is a noncriminal traffic infraction, punishable as a nonmoving violation as provided in chapter 318.

    (2) This section does not apply to the operator of:

    (a) An authorized emergency vehicle while in the performance of official duties and the vehicle is equipped with an activated antitheft device that prohibits the vehicle from being driven;

    (B) A licensed delivery truck or other delivery vehicle while making deliveries; or

    © A solid waste or recovered materials collection vehicle while collecting such items.
  7. FireEngineer

    FireEngineer Active Member

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    I do this all the time. if you have 6 bars on the battery, and everything is turned off, then you have about 20-25 minutes before the ICE kicks in.

    Wayne
  8. Ichabod

    Ichabod Artist In Residence

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    Hycamguy, you don't have SKS? Prius w/ SKS can easily skirt the law you reference because you can effectively shut the engine off (if you don't leave it too long) and take the key with you... ignition is locked... sort of. It will stop, but it won't start again :)

    In short, I think the only way someone will notice whether you car is "turned on" is if you have a pet in the car and they decide that you're being negligent... in which case you probably left in a note in the window saying "AC is ON, don't break the windows to save my dog!" Then they'll report you to the nearest authority for the above-stated non-moving violation :D
  9. hycamguy07

    hycamguy07 New Member

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    <div class='quotetop'>QUOTE(Ichabod @ Oct 19 2007, 10:31 AM) [snapback]527727[/snapback]</div>

    Being a former prius owner I know what to look for when owner leave the car running. ;)


    I had sks, but my doors wouldnt lock when the engine was running, if I removed the fob the car would just make that long beeeeeeeep sound...


    So if your an Honest person and you went somewhere, and left the car running. You put your key in your pocket so it wasnt really in the car. Would you tell your ins co. that you left it running?

    Here its a $72 ticket, its just another monthly stat added to my monthly quota, If the owner takes it to court I just bring the digital pictures along to show the judge. If I lose I look at it as either way I get paid for being there as the contestant has to take time off for court. ;)

    Anyways Im just glad I do not own a honda they are like # 1 cars to get stolen, because they are the fasts & easiest to steal.

    The kids know these cars, Ive seen where a kid will steal #1 car drive across town. Find another one and park the stolen #1 one next to the now newer stolen #2 car. Then drive stolen car #2 to another location just to steal car #3 to get back home.

    Why? just for fun.. BTW they trash each car before parking them.. :mellow:
  10. Ichabod

    Ichabod Artist In Residence

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    <div class='quotetop'>QUOTE(hycamguy07 @ Oct 19 2007, 11:31 AM) [snapback]527750[/snapback]</div>

    That's when you use the mechanical key to lock the doors... not that I'm advocating for leaving the car running, just that it can be done, and can be done in a relatively safe and stealthy way. I never have good enough tank MPG avg that avoiding cycling the power will really make that much difference anyway.
  11. RobH

    RobH Senior Member

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    <div class='quotetop'>QUOTE(hycamguy07 @ Oct 19 2007, 08:31 AM) [snapback]527750[/snapback]</div>

    "beeeeeeep" means that you left the car in Drive or Reverse. Not good. The reason it isn't moving is that you set the parking brake. Go back and press Park.

    "Beep Beep Beep" means that you took the keyfob with you while the car is still turned on.
  12. ChrisHenry

    ChrisHenry New Member

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    Learned something interesting.

    I do have SKS and found that if I leave the car on with the fob inside, but have the other one with me, I can force a door lock with the second fob from outside the car. The autosensing to lock and unlock the doors stops working, but I was able to lock the doors.

    Anyway, I'm not sure if I'll keep doing it as my stops are indeed generally less than 10 minutes and SoCal doesn't get all that cold.

    Thanks for an interesting disucussion.
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