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Batttery not being used when it should have

Discussion in 'Gen 2 Prius Main Forum' started by minime, May 22, 2006.

  1. minime

    minime New Member

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    Yesterday I had a weird problem with my 2006 Prius. The battery was fully charged (all green bars in the energy monitor screen and just came down a long hill). I was going up a very steep mountain and the energy screen was showing no energy coming out of the battery and engine was outputing power to the drive and the electric motor. It continued doing this for at least 5 minutes. I do this commute every day so normally the battery is outputing to the electric motor the entire time up this mountain. I knew something was wrong so I pulled over and stopped the car and turned off the power for a minute or so. Turned it back on and continued going up the mountain and now the battery was discharging power to the electric motor as is should.

    Anyone know why the battery wasn't powering the electric motor when it was fully charged?
     
    #1 minime, May 22, 2006
  2. SomervillePrius

    SomervillePrius New Member

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    Hmmm

    My initial guess would be that the engine wasn't warm enough so the Prius decided to run the engine more to get the heat up. The prius will sacrifice short term mialge to get the cat up. But since you ride the same route everyday I'm less sure. It could still be true though.

    My other guess would be SW glitch
     
    #2 SomervillePrius, May 22, 2006
  3. efusco

    efusco Moderator Emeritus
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    There are so many variables possible here. It was silly to shut down. No, you didn't do any harm other than burn a little extra gas and lose a little time, but it wasn't necessary.

    Just b/c a situation seems unlikely/unfamiliar to you does not mean there is anything wrong.

    And here's the REAL irony, you were in a very efficient condition when there was no battery drain! Power straight to the wheels without being converted to the battery and back is much more efficient. I suspect you saw this condition due to warmer weather conditions...but that's, frankly, a guess. Without knowing exactly what the MG1, MG2, and ICE RPMs were as well as the battery, ICE and inverter temps it's so difficult to know exactly what "should" have been going on.
     
    #3 efusco, May 22, 2006
  4. minime

    minime New Member

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    <div class='quotetop'>QUOTE(efusco @ May 22 2006, 11:44 AM) [snapback]259302[/snapback]</div>
    efusco -

    It was very warm 90 degrees Farenheit. So, I think you may be on to something here. But the MPG during this time was lower than if the battery was being used. I believe it was getting around 9-12 mpg where it normally gets 12-15 on this very steep hill (I live in the Rocky Mountains).

    You know alot more about this than me. How would the temperature play into this situation where the fully charged battery not being used when the engine is under a power demand?

    thanks

    Steve
     
    #4 minime, May 22, 2006
  5. efusco

    efusco Moderator Emeritus
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    <div class='quotetop'>QUOTE(minime @ May 22 2006, 01:57 PM) [snapback]259309[/snapback]</div>
    That is a temporary condition. Although the instantaneous MPG number would, indeed, be higher when the battery is being used that energy is not as efficient as the power coming directly from the ICE due to the multiple conversions it must go through to be used. I know this seems counter-intuitive, but when you are going 30mph on battery only and showing 99.9mpg that is NOT, necessarily, more efficient than going 30mph with the ICE running and showing 30mpg. It depends on a number of factors.

    The ICE can run much more efficiently at warmer tempertures and thus requires less 'assistance' from the battery under some conditions. It may be that the slope of the hill/road you were on is steep enough to normally need the extra battery boost to keep the ICE RPM within it's most efficient range. But on this warmer day your higher tire pressure (have you checked them since the temps came up?) and more efficient ICE, plus the extra BTU of the summer fuel formulation made the battery 'boost' unnecessary for this hill. The ECU would, thus, conserve that battery power until it was really needed.
     
    #5 efusco, May 22, 2006
  6. ken1784

    ken1784 SuperMID designer

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    <div class='quotetop'>QUOTE(minime @ May 23 2006, 03:57 AM) [snapback]259309[/snapback]</div>
    My bet is the HV battery was too hot, then system refused to use the battery.
    With the EV switch, we know the system refuses to enter the EV mode until the battery temp is 45C or below.

    Ken@Japan
     
    #6 ken1784, May 22, 2006
  7. jamarimutt

    jamarimutt New Member

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    It may also have been a computer glitch, like one I experienced recently when the brake malfunction light came on and the ICE was unable to power the wheels; it would only charge the battery and I could only more forward slowly, as if running in reverse. Turning the car off and on (as in restarting Windows) solved the problem, so you may have done the right thing, after all.
     
    #7 jamarimutt, May 22, 2006
  8. efusco

    efusco Moderator Emeritus
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    I don't think so jamarimutt. There were no warning lights and the car didn't have any loss of power or otherwise behave in an abnormal way. He simply became concerned about what was being shown on the (notoriously inaccurate) Energy screen display.

    I think that Ken is correct that the battery temp may very well have also been a factor.
     
    #8 efusco, May 22, 2006
  9. Orf

    Orf New Member

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    Well, I have another oddity.
    I recently noticed something strange with how the ICE is operating.
    Drove home about 4 Km and twice I changed from the Energy display to the Consumption display and back again.
    Once when the Energy display was showing I was driving on battery only the Consumption display show a fuel consumption of about 2.5 L/100Km.
    The second time I changed displays was when the car was slowing down and the Energy display showed only the wheels charging the battery while the Consumption display once again showed a fuel consumption of about 2.5 L/100Km. In neither case was the A/C on and the battery was about 3/4 charged.
    Is this a fault or is it normal?
     
    #9 Orf, May 22, 2006
  10. hobbit

    hobbit Senior Member

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    You could have also been seeing a "maintenance cycle", or a
    "recalibration" as it's called in Insight-land. The system tries to
    take the battery all the way down, and then all the way up, or the
    inverse, and then return to normal operation. The more mountains
    you do, the more likely it's said to occur. The intent is for the
    BMS to re-establish various thresholds.
    .
    _H*
     
    #10 hobbit, May 22, 2006
  11. ken1784

    ken1784 SuperMID designer

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    <div class='quotetop'>QUOTE(Orf @ May 23 2006, 12:04 PM) [snapback]259525[/snapback]</div>
    My bet is you're in Stage 3 idling check mode.

    (edit: add KB URL http://priuschat.com/forums/kb.php?mode=article&k=14 )

    Ken@Japan

    <div class='quotetop'>QUOTE(hobbit @ May 23 2006, 12:13 PM) [snapback]259529[/snapback]</div>
    There was such "maintenance cycle" on MHW-10 original Prius.
    I've never heard about it on NHW-10 nor NHW-20.

    Ken@Japan
     
    #11 ken1784, May 22, 2006
  12. wrprice

    wrprice Active Member

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    <div class='quotetop'>QUOTE(ken1784 @ May 22 2006, 10:51 PM) [snapback]259548[/snapback]</div>
    I've seen my '05 do what I could only explain away as a "maintenance cycle" before. Mostly flat metro driving, 35mph. That's my commute. There was a day or so where it would insist on pushing the battery into the green bars. I could still use the battery for acceleration and it would come back down to blue, but in no time it would run the ICE no matter how lightly I pushed on the accelerator to get it back to green. I thought it was the "maintenance" mode I read about because previously I had noticed that I was having an easier time "stealthing" for longer distances and I had been bringing the SOC down pretty low during regular driving (no EV mod).

    Admittedly, it was during some cooler Texas weather (but let's be clear -- it doesn't get that "cold" here), so maybe it was a low HV battery temp... but in response I note that the days prior to and following this odd SOC cycle, the temps (night & day) were pretty much the same across the board. It wasn't like we had a cold snap.

    But I have the general feeling that your technical expertise outweighs mine, Ken, so I'll defer to your judgement.
     
    #12 wrprice, May 23, 2006
  13. ken1784

    ken1784 SuperMID designer

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    Thank you for your comments.
    <div class='quotetop'>QUOTE(wrprice @ May 23 2006, 01:43 PM) [snapback]259571[/snapback]</div>
    I believe it is a battery warming up process when it's cold.

    The "maintenance cycle" is some what different, I believe.
    The system intentionally cycles the battery from the top to the bottom no matter how you drive it.

    Ken@Japan
     
    #13 ken1784, May 23, 2006
  14. efusco

    efusco Moderator Emeritus
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    <div class='quotetop'>QUOTE(ken1784 @ May 23 2006, 12:36 AM) [snapback]259585[/snapback]</div>


    This has, indeed, been reported in the '04+ Prius. Wayne Brown, Dan Krousel and others whom are quite familiar.
     
    #14 efusco, May 23, 2006
  15. samkusnetz

    samkusnetz New Member

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    <div class='quotetop'>QUOTE(hobbit @ May 22 2006, 07:13 PM) [snapback]259529[/snapback]</div>
    this is very educational... i just crossed the rockies in my month-old prius, and noticed extreme variations in SOC at the end of the day. this is clearly what was going on.


    thanks.

    sk
     
    #15 samkusnetz, May 23, 2006
  16. Orf

    Orf New Member

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    <div class='quotetop'>QUOTE(ken1784 @ May 22 2006, 10:51 PM) [snapback]259548[/snapback]</div>
    In my case it was not a battery maintenance cycle. The battery never went below 1/2 way and never went into the green.
    Also, I am having trouble getting reasonable fuel consumption and I thought the two problems could be linked.
    My car has done 1200 Km (745 miles) and the FC shown on the MFD is 5.3 L/100Km (44 MPG).
    To check the fuel usage, I went for a trip of 55 Km (34 miles) each way on a highway. Both departure point and mid way point were just a few metres above sea level and the highway went through rolling hills - nothing steep and not above 300 feet above sea level.
    I used the cruise control set to 85 Km/h (53 MPH) both ways to eliminate any driver input. There was a head wind of about 6-10 Km/h going which turned into a tail wind coming home. The out side temp was 13ºC and the air conditioning was turned off and my tyres were inflated to 38 - 40 psi.
    Here are the figures I achieved:
    Going into wind
    - Averaging out the 5 minute bars = 4.9 L/100Km.
    - Regeneration = 2 bars with 1/2 a car, 1 bar with 1.5 cars.
    Going down wind
    - Averaging out the 5 minute bars = 4.7 L/100Km.
    - Regeneration = 2 bars with 1/2 a car, 1 bar with 2.5 cars.
    Giving me an over all average of 4.8 L/100Km (49 MPG).
    To me, the fuel consumption figures I am getting seem much lower than those of other people posting on these forums.
     
    #16 Orf, May 24, 2006
  17. ken1784

    ken1784 SuperMID designer

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    <div class='quotetop'>QUOTE(Orf @ May 24 2006, 01:22 PM) [snapback]260147[/snapback]</div>
    My comment for you, Orf, was "My bet is you're in Stage 3 idling check mode." regarding to your post about 2.5L/100km display.
    The comments about "maintenance cycle" was for hobbit.

    I think it is too early to jugde your mileage before broken-in.

    Ken@Japan
     
    #17 ken1784, May 24, 2006
  18. flynlow

    flynlow Junior Member

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    I have about 800 miles on mine. My 30 mile commute through relatively flat 2 lane roads at 50-55mph nets me between 49 and 50mpg.. If I pay attention to my driving I can get 51,52mpg. OAT averages 55 degress. So not that much lower mpg.. unless we both have a problem :)
     
    #18 flynlow, May 24, 2006
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