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Auto Shut Off - Accessories

Discussion in 'Gen 2 Prius Technical Discussion' started by ibcs, Jul 23, 2007.

  1. ibcs

    ibcs New Member

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    Hi Everyone,

    Last night the family, 2 kids and wife, went to the drive inn theater. I put the car in accessory by pressing the power button without my foot on the brake pedal. We watched about 1 hour of the first movie and the car shut off. My understanding was that the accessories would last until the battery was dead. So not thinking, I went in the car and pressed the power button again. We watched another 30 minutes or so and again the radio went dead and the car powered off. I did this two more times, trying to not miss the movie while the oldest kid, 13, laughed at my baby. Finally, the last time, the accessories would not come on anymore and the inside light when opening the drivers door seemed dim. I thought we were going to be stranded. To my surprise, I pressed the power button twice and drove away without problem.

    To help analyze the situtation, I do have a small sub-woofer, kenwood, installed that was playing. I also have the car computer that was on under the back hatch, but I did not think of that until this morning.

    My question does the car know to shut down when the 12v is about to die? Does the traction battery recharge the 12v battery immediately upon being discharged? By the way, the traction battery had six bars when we drove away.

    I know know, I should have powered down the car computer, but this behavior seemed very strange. Can someone explain it?
     
  2. Trevor

    Trevor Member

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    They ICE (gas engine) would have come on and charged the 12volt if you had the car in park or pressed the start button twice without your foot on the brake. Without your extra gadgets, the radio might have lasted long enough for the movie in only Accessory-on mode that you were in. The traction battery does not directly charge the 12v.
     
  3. ibcs

    ibcs New Member

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    <div class='quotetop'>QUOTE(Trevor @ Jul 23 2007, 09:30 AM) [snapback]483538[/snapback]</div>
    Would I have been stuck with a dead battery had I kept playing the radio? How did the car start with the 12v battery being discharged?

    Thank you for your quick reply. I do understand had I had the power on twice, the car would have charged it.
     
  4. richard schumacher

    richard schumacher shortbus driver

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    When in ACC the radio shuts itself off after an hour, but that is the only thing that shuts itself off so it is still easy to kill the 12V battery.

    There's really no reason not to just leave the car ON when parked in a situation like this and let it manage its own energy levels.
     
  5. ibcs

    ibcs New Member

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    <div class='quotetop'>QUOTE(richard schumacher @ Jul 23 2007, 09:58 AM) [snapback]483550[/snapback]</div>
    Thank you, I now understand - let the car do it's thing and enjoy the movie.
     
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    Yeah, in ACC, it shuts off every hour. The 12V battery is smaller than normal so it'll drain quickly.
     
  7. David Beale

    David Beale Senior Member

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    Further, when in "ready" the car will charge the 12V battery from the traction battery. The engine will be used to power the MG (MG2 I think) and charge the traction battery, not the 12V battery, though the end result is the same. The 12V battery is only charged by the charging circuit in the HSD, which is powered by the 208V from the traction battery (and MG2 when it is being used as a generator).

    Note that the traction battery has about twice the energy of a "normal" 12V car battery (when it's fully charged). So it's probable if you sat and watched the movie in ready, the only time the engine would run would be to keep the cat warm, as the audio system doesn't draw enough to greatly discharge the traction battery over 2-3 hrs. I haven't tried it, but probably 30 sec. of running every 10 min or so.
     
  8. 1fixitman

    1fixitman Member

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    <div class='quotetop'>QUOTE(ibcs @ Jul 23 2007, 09:32 AM) [snapback]483539[/snapback]</div>
    The car is started by the traction battery. The car only uses about 30 amps(from the auxbattery) to power/boot up the ecm and MFD. Once booted properly the ecm will start the car with the traction battery via one of the MG's. I can not remember which one at this time. I would recommend letting the car stay in the ready mode as described before or using a jumpstart/recharable battery pack to supply voltage to the cigarette lighter while watching the movie. I really did not know about the radio shutting off every hour so that is new news for me. Read many threads on this site over the next few weeks and you will understand much more about your vehicle than the average prius driver on the road. Good luck in the future.
    D Rock
     
  9. Bill Merchant

    Bill Merchant absit invidia

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    <div class='quotetop'>QUOTE(Trevor @ Jul 23 2007, 06:30 AM) [snapback]483538[/snapback]</div>
    You are misinformed. The ICE will not start in Ig-On mode as you describe; it will only start in READY mode. As noted by others, the audio system automatically shuts off after an hour except in READY mode. The HV traction battery directly charges the 12V battery in READY mode.
    <div class='quotetop'>QUOTE(David Beale @ Jul 23 2007, 02:21 PM) [snapback]483754[/snapback]</div>
    The HV battery has quite a bit more than twice the Amp-hours of a "normal" 12V car battery.
     
  10. David Beale

    David Beale Senior Member

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    <div class='quotetop'>QUOTE(Bill Merchant @ Jul 23 2007, 10:45 PM) [snapback]483981[/snapback]</div>
    Traction battery is about 6 A-Hr and 208 V - that's 1248 W-Hr

    "Normal" (big these days) lead acid car battery is 50 A-Hr at 12 V - that's 600 W-Hr.

    I repeat, traction battery has about twice the energy of a "normal" automotive lead acid battery.

    ;)
     
  11. aaf709

    aaf709 Ravenpaw of ThunderClan

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    An alternative would be to bring your own portable radio and use it for the sound.
     
  12. lagreca

    lagreca Junior Member

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    I took my new 2007 Prius to the drive in last weekend. I had the same problem of the radio shutting off after an hour when in ACC mode. I tried turning the car to IGN-on mode, but all the dash lights lit up, and it was hard to look at the screen, with the glaring lights in my eyes.
     
  13. dogfriend

    dogfriend Human - Animal Hybrid

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    <div class='quotetop'>QUOTE(D Rock @ Jul 23 2007, 03:19 PM) [snapback]483784[/snapback]</div>
    MG2 is connected directly to the wheels (thru the differential and reduction gears) so, when the car is stationary, MG1 has to start the car because MG2 is not moving.

    When the car is moving, there is a bit of a semantic argument over which MG is actually starting the car, but if you think about how the PSD (power split device) works, when the engine is off (rpm = 0) , MG1 has to be controlled to maintain the engine rpm at 0 while MG2 turns at whatever speed the car wheels are turning (thru diff and reduction gears). So, to start the engine, the HV ECU changes the speed of MG1 to whatever speed is necessary to make the engine rpm = ~1000 rpm, then adds fuel and spark, and the engine starts. Because of the PSD, I would argue that both MGs are involved in starting the engine when the car is already moving.
     
  14. zenMachine

    zenMachine Just another Onionhead

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    <div class='quotetop'>QUOTE(aaf709 @ Jul 24 2007, 11:46 AM) [snapback]484174[/snapback]</div>
    Must you point out the obvious? You're no fun at all!! :D

    Kinda interesting thread, actually. I didn't even know drive-in movies still existed!
     
  15. zenMachine

    zenMachine Just another Onionhead

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    <div class='quotetop'>QUOTE(lagreca @ Jul 24 2007, 05:50 PM) [snapback]484382[/snapback]</div>
    Next time bring along a towel and drape it over the dashboard. Problem solved! :)
     
  16. hill

    hill High Fiber Member

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    A 'Drive-In' ?!? What's that? Oh! Ohio ... now I get it ... hey, I've watched the history channel, I now what a drive-in is now. :p

    Ok, so I'm 51 an I really do know what a drive in is. They actually do still have one about 10 miles north of our town in MT. And in CA, that's where my parents took us kids to watch James Bond / Gold Finger, back in the '60's. Yea, I guess most of us that remember drive-in's are fossles.
     
  17. Frank Hudon

    Frank Hudon Senior Member

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    <div class='quotetop'>QUOTE(dogfriend @ Jul 24 2007, 08:30 PM) [snapback]484495[/snapback]</div>
    depending on the speed of the car MG1 will spin "backwards" to start the ICE. Other times it slows or stops.
     
  18. aaf709

    aaf709 Ravenpaw of ThunderClan

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    <div class='quotetop'>QUOTE(zenMachine @ Jul 25 2007, 05:29 AM) [snapback]484604[/snapback]</div>
    Then you should go to http://www.driveintheater.com/index.htm. They have a list of theaters and sometimes what's playing. :)
     
  19. Tideland Prius

    Tideland Prius Moderator of the North
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    <div class='quotetop'>QUOTE(lagreca @ Jul 24 2007, 03:50 PM) [snapback]484382[/snapback]</div>
    You can turn off the screen.
     
  20. lagreca

    lagreca Junior Member

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    <div class='quotetop'>QUOTE(Tideland Prius @ Jul 25 2007, 10:43 AM) [snapback]484772[/snapback]</div>
    I did turn off the screen. Its the lights on the dash that were bothering me.

    I guess the only way around it is to toss a towel over them, as someone mentioned before. Just wish there was a better way.