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More Elusive than the "Floating" Car in Regen

Discussion in 'Gen 2 Prius Technical Discussion' started by CBarr31, Apr 13, 2010.

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  1. "Floating Car" in the 5 minute period for regen.

    2 vote(s)
    40.0%
  2. More than 3 cars in the 5 minute period for regen.

    3 vote(s)
    60.0%
  1. CBarr31

    CBarr31 Active Member

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    Hello all, just a post and a poll here on a curious sighting I had in Ema the other day.

    Having owned a Prius since 2006 and been a member of this community for a couple of years now I have learned a lot of cool facts and info on the Prius. One particularly interesting tidbit is the elusive "floating car" you can get when you have regen but your MPG graph is zero so it looks like the little car regen symbol is just hanging on the screen.

    I looked for old links with this in it and a photo but couldn't find one. If someone has one please add it so people know what we are talking about if they don't already.

    I can get the floating car myself and have seen it a half dozen times or more but what I have NEVER seen before is more than 3 cars regen in a single 5 minute period. I even ran my battery completely down to purple at the top of the big hill on I-40 near Asheville and regened the whole way down it to see if I could get more than 3 cars and never have.

    Then the other day I saw the picture attached to this post. A half of a 4th car in a single 5 minute period!!! Obviously I was somewhere cold, LOL and it was under winter MPG's :( but otherwise I don't remember anything unusual about the situation.

    I was wondering is this more elusive than the floating car? Just posting and polling for the sake of interest, enjoy.

    Happy driving,
    Chris
     

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  2. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    I honestly don't know what you mean by "floating" car.
     
  3. CBarr31

    CBarr31 Active Member

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    Tony,

    In my picture you see the 3.5 green cars showing regen layed over the yellow bar graph. You can get, under certain situations, where there is a complete green car showing regen but absolutely no yellow bar graph.

    So it looks like you regened at 0 MPG. Hence the "floating car" people often refer to. Like I said I couldn't find a picture. Hopefully Hobbit, Evan or someone will know where to look. It would help if there was one with this post.

    Chris
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    I'm trying to figure out how to produce this "floating car" since I've never seen that in my driving. I suppose you would wait for the 5 minute interval to start, then head down a hill at a fast speed to quickly produce sufficient regen to create one floating car, which would mean 600W of regen.

    As soon as the floating car is created, stop and turn on the windshield defroster, and select MAX HEAT as cabin air temp, so that the engine and AC compressor are running. Sit and wait for the remainder of the 5 minute period to elapse. I suppose that might create 0 mpg over the 5 minute period?

    I recall seeing 3.5 cars over a 5 minute period in the past, but never thought much of it.
     
  5. Politburo

    Politburo Active Member

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    I've gotten the floating car a bunch of times. But I don't know if I've ever gotten it with a zero bar. Usually it's like 15 mpg or so with 2-3 cars, so the last one is "floating" off the bar.

    I get 3.5 not infrequently. Have never seen 4 though.
     
  6. uart

    uart Senior Member

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    In Australia and (other countries that use L per 100k) you get zero (L/100k) on the bar graph display when the fuel usage is zero, so it's very common to get "floating cars" when going down hill. Not that I've ever thought anything of it. :)
     
  7. sub3marathonman

    sub3marathonman Active Member

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    That is not the way to get the "floating car."

    What I would call an "infinity bar" is a 5 minute period where the car has not burned any gas, but has moved, even just a small amount, on electric. The "floating car" then appears if you have done the regen during that time period.

    If you get the car going on electric to 20 mph, then stop, then to 20 mph, then stop, etc. until the battery is down but not so low that the engine starts the second you start moving forward, you should be able to generate the "floating car."
     
  8. Tideland Prius

    Tideland Prius Moderator of the North
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    We get it all the time (b/c we use L/100km not mpg =P).

    Hmm, Patrick, what if you idled for 5 mins in traffic and all this while, the stop and go allowed you to regen 50Wh?



    I thought the max was 4 leaf cars?? I remember I was half a leaf short of max (thus 3.5 leaf cars).

    In the 2010, you can get a tall stack of leaf cars (esp. if you cheat and use the 1 min bars which change the Wh each leaf represents... I think I got 7??
     
  9. patsparks

    patsparks An Aussie perspective

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    I just looked at your photograph, and you need to move south. Bloody cold there hey?
     
  10. Tideland Prius

    Tideland Prius Moderator of the North
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    The one I posted in December? haha yeah... It's +15°C now
     
  11. Tom Banjo

    Tom Banjo New Member

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    my "floating Car" today, I was coming off the hiway and stuck at a train crossing for nearly ten minutes

    [​IMG]
     
  12. CBarr31

    CBarr31 Active Member

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    Here is a picture of a "floating car" that I generated while at the Charlotte airport waiting in the cell phone lot.

    I basically coasted down the hill at low speed from the long term lot area into the cell phone lot and then put the car in park.

    Basically the "floating car" is a math rounding issue with the computer, I think. It sees that you regenerated so it gives you the car or half car symbol but the distance you traveled during that regeneration somehow rounds to zero. Usually this is because you are stuck in traffic, at a railroad crossing or in a cell phone lot, LOL.

    I have found that it is easiest to generate the "floating car" at lower but not low low speeds, somewhere in the 20-30 MPH range, where you can coast down a decent hill for less than a mile and put the car in park and just sit for the rest of the 5 minutes. You get the regen from the hill but the distance is less than a mile so shows zero on the bar graph. Voila!!!! "Floating Car"

    What may be the most impressive thing I have EVER seen with regards to this is the picture in this thread.

    http://priuschat.com/forums/gen-ii-prius-fuel-economy/80257-ever-seen.html

    Not only was a "floating car" generated but TWO were generated in the second zero MPG 5 minute segment. To quote Darth Vader ... "Impressive, most impressive."

    Happy driving,
    Chris
     

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  13. Bob64

    Bob64 Sapphire of the Blue Sky

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    its a divide by 0 error. if u travel x distance, divided by 0 fuel....
     
  14. vertex

    vertex Active Member

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    I noticed blank bars when the car is ready, but not moving. I suspect there is a small timing error in the calculation, and the car actually belongs to the prior 5 minute period.
     
  15. sub3marathonman

    sub3marathonman Active Member

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    No, it isn't a "timing error," the car doesn't belong to the prior 5 minute period. It isn't a "math rounding issue with the computer" either. It is what Bob64 just said, and I said awhile back.

    If you travel any distance in a Prius and it burns fuel, no matter how small an amount, you will see the yellow bar. (Unless of course you're burning fuel and not moving forward enough to get more than 0 mpg.) If you travel any distance in a Prius, and burn no fuel by using only battery power during the 5 minute interval, no matter how far whether it is a mile or three inches, you will get an "infinity bar." If you have regenerated enough to merit a car or a half car or even two or three cars, you will see it. I just saw an "infinity bar" today with two regenerated cars, which I hadn't seen before. I am always attempting to avoid the regenerated cars, it still shows energy was wasted, even though a portion was recovered.
     
  16. CBarr31

    CBarr31 Active Member

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    Bob64,

    It isn't a divide by 0 error it is a division OF 0 error. Remember the Prius sees battery power as "fuel" so if you travel 2 miles on battery alone you get the 99 MPG bar.

    Where as if you travel less than 1 mile or whatever the Prius software rounds to zero, even if you used battery power you still show an empty bar graph. Now the question becomes did you regenerate enough in the < 1 mile to show a half car, full car or even an amazing 2 cars regenerated?

    Chris
     
  17. CBarr31

    CBarr31 Active Member

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    Sub3marathonman,

    I know you describe your "infintity bar" in an earlier post but you might want to start calling it an "empty bar" or "zero bar" instead.

    Infinity by definition is 1. unlimited extent of time, space or quantity 2. an indefinately great number or amount.

    So when someone sees something called an "infinity bar" one assumes it is huge, in this case the full 99 MPG yellow bar on the Prius consumption screen. And even though you describe it as otherwise I am sure it still confuses people.

    Happy driving,
    Chris
     
  18. Patrick Wong

    Patrick Wong DIY Enthusiast

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    OK, here's my contribution to this string. I was very surprised when this appeared because the car was just moving downhill, it was not stopped for most of that five minute period, etc.

    My theory is that this floating car phenomenon is temporary weirdness produced by the MFD display logic (i.e., a glitch.) I don't think it can be explained by actual distance traveled and fuel consumed over the five minute period.
     

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  19. Bob64

    Bob64 Sapphire of the Blue Sky

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    Actually no. The Prius requires some fuel to be used in a given 5 minute segment in order to calculate mpg. Try it on a 5 minute downhill next time (avoiding speeds above 40mph at all costs, as starting up the ICE will use up 1tbs of gas).

    Edit: just saw pat's post. Perfect example. Basically what happens is every 5 minutes, it will record the distance traveled and the gas used, then divide distance by gas. In all cases where you use 0 gas, and travel a distance, the bar will be &quot;empty&quot; due to a divide by 0 problem. It's just rare since its usually very hard to use 0 fuel in 5 minutes of travel.
     
  20. CBarr31

    CBarr31 Active Member

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    Bob64,

    I have and it goes to 99 MPG, full bar. Like I said earlier I have stopped just after the truck brake safety check area on I40 coming out of Asheville towards Hickory and drained my battery all the way down to purple then let the motor re-charge to 3 blue bars and stop. Release the brake and coast the rest of the way down the 5 mile or so stretch.

    People aren't real happy at the beginning but I stay in the truck lane until I get up to 60 or so unless I have to pass one, a truck that is. I was trying to get more than 3 full cars regen but never have even when the battery SOC goes full double green.

    Also, I will try this today and report back but if you go to Walmart or some school parking lot and drive in circles at a low speed for more than a mile on battery only you should get 99 MPG. Have to make sure I do this soon before it gets to hot so I don't have to run the AC, lol. That will discharge and cause the motor to come on. I'll let you know.

    Patrick's theory may be be correct. Anyway you slice it, "Floating Cars" look cool :cool: :rockon: :cool:

    Chris