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Battery gauge bars - misleading?

Discussion in 'Gen 2 Prius Fuel Economy' started by KMO, Feb 22, 2005.

  1. KMO

    KMO Senior Member

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    Okay, I've seen lots of posts about the fuel gauge and its non-linearity - I've got a European, non-bladder car, and mine seems fine.

    But I am doubtful about the battery charge indicator. If I switch to EV mode, as I watch the Energy screen, it always seems to take a long time to go from 6/8 to 5/8, but then the next 3 bars vanish quite rapidly (EV deactivates the instant the indicator shows 2/8).

    So if I start at 6/8, I get the impression that at the moment the gauge moves moves to 5/8, I've exhausted more than half my EV range.

    Am I imagining things?
     
    #1 KMO, Feb 22, 2005
  2. efusco

    efusco Moderator Emeritus
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    There is definately some non-linearity, particularly with higher drain or charge rates.
     
    #2 efusco, Feb 22, 2005
  3. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    the entire charge display only represents a small range in the SOC of the battery.

    there are too many variables on how fast you will use the charge. many dont realize how much of a difference the volume of the stereo can impact the charge. then throw in lights, air conditioning, speed of vehicle, running time of ICE, etc...
     
    #3 DaveinOlyWA, Feb 22, 2005
  4. Tideland Prius

    Tideland Prius Moderator of the North
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    but I notice the bottom half of the battery recharges faster than the top half or is it just that the computers are sending a lot of the engine's power towards the battery pack when it's low?
     
    #4 Tideland Prius, Feb 22, 2005
  5. KMO

    KMO Senior Member

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    Okay, I've got confirmation of my suspicions from Attila Vass, who's been working hard on a CAN analyser.

    He reports that the battery bar has some hysteresis, so the transitions between bars are different depending on whether it's going up or down. But the CAN numbers are:

    Going down:
    8->7 @ 150 (75%)
    7->6 @ 128 (64%)
    6->5 @ 110 (55%)
    5->4 @ 104 (52%)
    4->3 @ 98 (49%)
    3->2 @ 90 (45%)

    When going up, the charge has to reach 5 (2.5%) above the downward transition threshold before changing.

    Thus, going up:
    2->3 @ 95 (47.5%)
    3->4 @ 103 (51.5%)
    4->5 @ 109 (54.5%)
    5->6 @ 115 (57.5%)
    6->7 @ 133 (66.5%)
    7->8 @ 155 (77.5%)

    Looking at it another way, the bar sizes are:

    8 = 10 (5%)
    7 = 22 (11%)
    6 = 18 (9%)
    5 = 6 (3%)
    4 = 6 (3%)
    3 = 8 (4%)
    2+1 = 10 (5%)

    So that matches my suspicions. Running in EV mode, if the gauge starts at 6, then the charge is probably around 60%, but it could be as high as 66%. It won't go to 5 until it reaches 55%, and it'll reach 2 at 45%.

    So maybe I was seeing the gauge start at 65% (=6), halfway it went to 5 @ 55%, then later it went to 2 @ 45%. 6->5 is the halfway point.

    And this is why you see it mainly at 6 or 7 bars - between them they cover half the usable charge range.

    All this is assuming that the CAN readings are linear - they're believed to be.
     
    #5 KMO, Feb 24, 2005
  6. efusco

    efusco Moderator Emeritus
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    Realize too that that range of SOC/voltage shifts with temperture...I think that's part of the reason we see a higher SOC indicated in colder weather than in warm weather.

    Below are a couple SOC diagrams that Wayne Brown determined using a voltmeter.

    This first one shows the voltages measured for each bar:
    [​IMG]

    This one is the percentage of SOC:

    [​IMG]
     
    #6 efusco, Feb 24, 2005
  7. Frank Hudon

    Frank Hudon Senior Member

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    Thanks Evan for posting that. This should help people get their head around the charge/discharge display of the Prius.
     
    #7 Frank Hudon, Feb 24, 2005
  8. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    very good info on this thread, definitely bookmark quality

    thanks all
     
    #8 DaveinOlyWA, Feb 24, 2005
  9. rbartels

    rbartels New Member

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    I've had a 2005 Prius for about 6 weeks and have a question about the battery gauge bars. I've read the posts that I could find but none directly answered my question. My gauge goes up to the 6/8 bar position but usually goes no higher. A handful of times it's BRIEFLY gone to 7/8 [and the display turned green], but I've NEVER seen it go the top 8/8 bar. Two times I've driven it for about 8 hours in one day at mostly highway speeds.
    My question: Is this normal?

    rbartels in San antonio, TX
     
    #9 rbartels, Apr 1, 2005
  10. Frank Hudon

    Frank Hudon Senior Member

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    yes it's probably nomal. I've only see the 2k4 BSOC at all green a very few times. Mainly in the winter when the ICE runs more often and at at bottom of a long hill. Start off from the bottom and it quickly goes down a bar or two. Very sensitive. You can't hurt it so just drive it.
     
    #10 Frank Hudon, Apr 1, 2005
  11. Poppajack747

    Poppajack747 Junior Member

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    Re: Battery gauge bars and warning indicators

    Today my warning indicators, ie. triangle with !, car with ! and check engine, all came on. When I accessed the battery gauge, there were only two pink bars. I turned off the engine, restarted and drove for about 2 minutes and everything but the "check engine" light went away. The battery gauge bars changed from pink to blue and soon were increased from two to 6 or 7. Then they momentarily changed from blue to green.
    I couldn't find any explaination for the colors in the manual.
    Is this a common "glitch?" Should I take it in immediately? What do the colors mean? What caused this?
     
    #11 Poppajack747, Apr 17, 2005
  12. Frank Hudon

    Frank Hudon Senior Member

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    you probably need the computer flashed, this is a fairly common complaint and well known. When the dealer pulls the codes it'll say engine failed to start.
     
    #12 Frank Hudon, Apr 17, 2005
  13. Poppajack747

    Poppajack747 Junior Member

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    I called the dealer and he said they couldn't do anything if the warning lights were not there as the diagnostics had reset themselves. Hadn't heard af this as a problem, either.
     
    #13 Poppajack747, Apr 18, 2005
  14. jayman

    jayman Senior Member

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    Bull.

    First, the Check Engine is still on? So the problem hasn't "cleared" and may not clear.

    Second, the Prius has Freeze Frame and will grab 5 frames to assist in troubleshooting.

    More than likely, you need the reflash done.
     
    #14 jayman, Apr 18, 2005
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