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Max speed in Reverse

Discussion in 'Prius v Technical Discussion' started by zhonda, Nov 9, 2011.

  1. zhonda

    zhonda New Member

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    With CVT and HSD, should the max speed in Reverse be the same as forward?

    Someone told me reverse is only using MG1 and or MG2? If that is the case, should max R speed be the same as max forward speed in pure EV mode only?
     
  2. pvogel

    pvogel '05 Five & '12 v

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    On ALL Prii, reverse is always 100% electric. However, I do not believe you have the full CVT gear range to work with, so I doubt you can get the car going 42 MPH in reverse. Haven't tried to max out the reverse speed so I can't tell you the actual max.

    Peter+
     
  3. KK6PD

    KK6PD _ . _ . / _ _ . _

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    I like to think I can get out of trouble faster than I got into it! :D
     
  4. spiderman

    spiderman wretched

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    25 mph I believe.
     
  5. dogfriend

    dogfriend Human - Animal Hybrid

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    Since the speedo reads out in R as well as D, all you need to do is throw it in R and see how fast you can go. :madgrin:
     
  6. qbee42

    qbee42 My other car is a boat

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    Reverse is done by MG2, so it is all electric. However, and this is a big however, if the Prius needs the ICE to charge the battery, the torque from the ICE works against going in reverse.

    Think of it this way: the mechanical gearing on a Prius is fixed. There is no reverse gear or clutch. This means that any time the ICE provides torque it attempts to move the Prius forward.

    When backing up with the ICE running, the ICE spins MG1 to make electricity. The electricity is used to power MG2 in reverse, but MG2 also has to fight the torque from the ICE. MG2 is stronger, so it wins.

    HSD is not efficient going in reverse, nor can it travel as fast.

    Tom
     
  7. Southern Dad

    Southern Dad Active Member

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    Oddball in Kelly's Heroes... I loved that movie.
     
  8. KK6PD

    KK6PD _ . _ . / _ _ . _

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    Very good, you are correct, you win a cookie! :D
     
  9. nerfer

    nerfer A young senior member

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    It's probably obvious, but it should be pointed out that with the steering in the back, control gets pretty squirrelly at high speeds, even if you're comfortable with driving in reverse.
     
  10. dogfriend

    dogfriend Human - Animal Hybrid

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    Plus, you're going to need to watch the speedo which is in the opposite direction compared to where you should be looking.

    Be sure to take video. :madgrin:
     
  11. cproaudio

    cproaudio Speedlock Overrider

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  12. zhonda

    zhonda New Member

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    Thank you, I think I found my answer in your video.


     
  13. epoch_time

    epoch_time Active Member

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    On a genII prius in reverse , mg1 doesnot charge the battery or provide power to mg2....reverse is powered by battery only....I would think prius V transaxle is similar to a genII .....
     
  14. qbee42

    qbee42 My other car is a boat

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    This is wrong. When needed, MG1 does indeed generate charge which is supplied to MG2. Otherwise a Prius with a low battery couldn't back up.

    Tom
     
  15. epoch_time

    epoch_time Active Member

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    watching energy monitor screen, which I think all prius have,..... you will never see arrows flowing into battery symbol while in reverse (which would indicate battery charging) charging doesn't happen ever in reverse (neither does mg1 supply power to mg2 while in reverse, also verified by prius energy monitor screen) .......................................Likewise using a scan-guage in (high voltage) current (amperage) monitor mode while driving or stopped in reverse you will neversee negative amperage readings (negative indicates charging when using scanguage, positive numbers indicate discharge)....................................................Furthermore if you deplete hv battey down to 2 pink bars by letting prius stand in neutral after warm-up..You can then drive in reversedepleteing the last two bars and getting warning messages from prius monitor screen stateing "battery is extremely low place car in park or drive immediately or battery will not charge in reverse or neutral"""""""" The prius is programmed this way to avoid the condition talked of earlier whereby load on mg1 produces forward wheel torque That mg2 would have to over-come to provide reverse motion....A wastefull energy condition that prius engineers have avoided.................
     
  16. Danny Hamilton

    Danny Hamilton Active Member

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    You know this from personal experience, or this is just something you've heard about? Because I can state definitively that just today while I was backing out of my driveway, the ICE came on.

    P.S. Please don't use so many periods, it makes the post difficult to read. A single period at the end of each sentence is sufficient. Ellipsis (. . .) to indicate missing text would be ok too.
     
  17. epoch_time

    epoch_time Active Member

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    Yes I know this from my personal experience with a 2006 rental and my 2009 prius purchased.And yes your ice will run in reverse but it will never be charging in reverse.
     
  18. Corwyn

    Corwyn Energy Curmudgeon

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    See: Toyota Prius - Power Split Device

    From this you can see max speed in reverse is 25 mph, if the engine is not running (which appears to be a soft limit); and 19 mph if the engine IS running (which is maxed out MG1).
     
  19. epoch_time

    epoch_time Active Member

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    I stated in some earlier posts that prius cannot charge hv battery in reverse....I discovered i'm wrong... If the prius hv battery is at 37% which is transitioning from two purple energy bars to 1 pink bar the prius will charge in reverse.....This condition is rare and If it should ever happen to anyone you will surely notice the excessive low frequiency roar as mg2 (used exclusively for reverse motion) over-comes forward motion caused by mg1's load as generator charging hv battery..***********Sorry for my mis-stated posts "it can never happen" sorry again.....It can happen......
     
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  20. milkman44

    milkman44 Active Member

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    I left the house and after about a mile, I discovered I had left my phone, backed down the road to the next driveway approx. 1/8 mile and top speed in reverse was an indicated 28 mph. :eek: