High pitched sound plus battery charging too much

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by gnrob, Jan 1, 2009.

  1. gnrob

    gnrob Junior Member

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    On Dec. 31, just after starting my 2007 Prius Touring and while backing out of the driveway, there was a noise like a coffee grinder that lasted for a half second and then repeated a second later. The sound seemed to come from the dashboard in front of the steering wheel, but it may have been from the engine compartment.
    Later that day and again today (Jan. 1) my wife could hear a very high pitched trill like sound, but I could not hear it, even with my hearing aids set to the highest boost. Then a lower pitched version of the same sound started to occur that I could hear quite well. It is similar to the referee's whistle in character, but not very loud.
    This sound does not occur when accelerating. It seems to come from the left front. It is much harder to hear from the rear seat.
    The sound is most obvious when maintaining constant speed on level roads. It will sometimes be only the very high pitched one and sometimes both. It will start as I lift off the throttle from acceleration to maintaining speed or coasting.
    Then I noticed that the battery is 9 green bars and the display shows the ICE charging even with the batteries in that highly charged state.
    The sound is present whether the A/C - heat is on or off.
    The speed of the car makes no difference in the pitch or intensity of the sound.
    MY Guess: The grinding noise had to do with the charging portion of the hybrid drive and the high pitched sounds are the after effects of whatever damage occurred.

    ANY IDEAS or similar experiences?

    Thanks,
    Rob M. :confused:
     
    #1 gnrob, Jan 1, 2009
  2. Bob64

    Bob64 Sapphire of the Blue Sky

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    The grinding sound may be the brake accumulator pump.

    Not sure about the other sounds, could be the inverter coolant pump.
     
    #2 Bob64, Jan 1, 2009
  3. patsparks

    patsparks An Aussie perspective

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    Check your front disc pads.
     
    #3 patsparks, Jan 1, 2009
  4. Rokeby

    Rokeby Member

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    Rob,

    perhaps you mean 7 bars, one from the top of the SOC window?

    There are only 8 bars total for SOC, in the HV battery, 10 pips (bars) for the
    fuel gauge. Easy to get them switched up when not in the car.
     
    #4 Rokeby, Jan 1, 2009
  5. gnrob

    gnrob Junior Member

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    I did not count them, just going on memory. Yes, it is the SOC display with all but one bar lighted, all green, not the fuel gauge.

    I am planning an early morning trip to the dealer and will post the results.
    Needed a 25,000 mile service anyway.

    I will have all of your suggestions checked while there.

    thanks,
    Rob
     
    #5 gnrob, Jan 1, 2009
  6. richard schumacher

    richard schumacher shortbus driver

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    The intermittent coffee grinder sound after startup and shutdown suggests to me a noisy coolant transfer pump. Mine has done this every winter's day for four years and the pump still works fine, so if that is indeed the source don't let the dealer scare you into paying for a new one without further evidence of a problem (of course if it is a free replacement under warranty, go right ahead).

    The soft high-pitched whine sounds very much to me like normal electrical inverter and motor controller noise. You might be amazed at how long people can drive a Prius without noticing that, and many other normal things.

    In any case, if there is a real problem it will almost certainly create a "trouble code" in the computer which the dealer can report to you (and you to us). If not, be suspicious.
     
    #6 richard schumacher, Jan 2, 2009
  7. butchbs1985

    butchbs1985 Taking things apart is fun!

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    Agreed that grinding is likely the coolant pump. Mine is quite loud as well when it's cold. Also agreed that the whistle noise is likely the inverter noise (especially since you said it happens when you release the pedal). My Prius seems to make a louder whine from time to time. Haven't thought much of it.
     
    #7 butchbs1985, Jan 2, 2009
  8. gnrob

    gnrob Junior Member

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    A visit to the dealer revealed that the source of these noises was a small tree branch that got pulled up into the "works". I remember running over the small branch. It dragged on the pavement for about half a minute, then the dragging sound stopped and I assumed that the branch had dropped off.
    The mechanic believes that the grinding noise was the branch being pulled up into the moving parts. The high pitched sounds were from the smaller bits of the branch rubbing on moving parts.
    The dealer did not charge for tree removal.:p
    The normal 25,000 service was done and all is quiet in my Prius once again.

    Moral of the story: Look for the simple explanation first.

    Thanks for all your ideas.

    Rob
     
    #8 gnrob, Jan 2, 2009
  9. butchbs1985

    butchbs1985 Taking things apart is fun!

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    Interesting. Perhaps watch out for trees in the future??:rolleyes:

    Glad it's fixed though!
     
    #9 butchbs1985, Jan 2, 2009
  10. davidtm

    davidtm Member

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    I had thought of that explanation, but did not want to go out on a limb to say so. :)
     
    #10 davidtm, Jan 3, 2009
  11. patsparks

    patsparks An Aussie perspective

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    Well done, very well done.

    Ever thought of branching out into comedy?
    I guess you feel you should stick to what you're doing.
    Wouldn't want to leaf your current job in the current economic climate.
    But now that Bush is gone things will improve.:rofl::bolt:
     
    #11 patsparks, Jan 3, 2009
  12. richard schumacher

    richard schumacher shortbus driver

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    'E's barking mad, 'e 'is.

    I'm glad the OP's problem had a simple explanation and solution, but it's irritating not to learn all the relevant facts before we launch into a buncha long-winded speculations. "Oh yeah, the noise didn't start until right after I drove over this fallen tree. Do you think they could be related?"
     
    #12 richard schumacher, Jan 3, 2009
  13. bwilson4web

    bwilson4web BMW i3 and Model 3

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    A little off-topic but that "High pitched sound" reminds me of what happened back in the 1970s when I had a 4-seat, Cherokee 140.
    I was washing the plane one day and a mother and her three kids, ages 5-9, came out to watch the planes. So I let them play with the soap and water while I got the bugs off.

    Well I had this wet airplane and a perfectly fine day so I asked the mother if she'd like her kids to have an airplane ride? She agreed and the kids were quite happy. So we loaded up the plane and I fired her up and taxied to take off. Everyone was quite happy until the takeoff.

    Just as I was committed, the kids began screaming and it didn't stop until I landed and pulled onto the taxi-way. We're talking pure stark terror, not "yippie!" That was one of my fasted circuits I'd ever made ... more like a "Ok, I'm high enough let me get this puppy back on the ground. NOW!"

    Then like a switch, pulling onto the taxi-way and the kids were suddenly giggly again and happy about the flight. But there was no way I was going to offer them another flight. Soon as I got the engine off and brake set, they were out of my plane forever!

    NOTE: Whenever you are piloting a plane and forget your favorite pen, don't say "Oh Darn!" Your passengers are likely to misunderstand what is going on.
    ​
    I'm glad to hear your problem turned out to be as easily solved.

    Bob Wilson
     
    #13 bwilson4web, Jan 3, 2009
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