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hybrid battery went too low

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Drifter, Aug 23, 2013.

  1. Drifter

    Drifter Member

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    I haven't posted here for years but I had an issue that I'd like some opinions on.

    I have a 2005 prius that is coming up on 90K miles. I was driving at very low speeds for 10-15 minutes in hot weather with the air conditioning on pretty high and decided to go though a drive-through next door to my final destination. While doing the stop and go drive through thing my car beeped and gave me the red triangle warning and complained that the battery won't charge in neutral and that I should put the car in park. I looked at the hybrid battery charge and it was down to two (pinkish?) bars. (I know it will sometimes go to two bars but it should start the engine to charge it at that point right?) Let me state that I was not in neutral at any time (and the door stayed closed, I know that also gives the warning). I put the car in park and I think it stopped complaining but then as soon as I went back to drive it complained again. I turned off the a/c and drove next door to my destination and turned the car off. I'm pretty sure the engine did not turn on during this time. I restarted the car and it didn't immediately complain, but I didn't really have time to mess with it then. When I came back to the car a couple hours later it started up ok. I drove in circles around the parking lot for about five minutes, kind of forcing the engine to kick on when it turned off to make sure the battery was charging right. (it didn't seem like it the engine should turn off even at low speeds until the battery reached 3 bars, but it did) After it was up to three bars I drove the hour plus home. This was about two months ago and I haven't had a problem with it since. I have blamed the 12 volt battery and am having it replaced today just in case, but I just saw that it is only 3 years old not the 4 years I thought. Is there a better explanation to what happened? Something else I should get checked out? I should have posted this right after it happened so I'd remember it better. Thanks in advance for your comments.

    By the way does anyone in the chicago area still do meet-ups? Its been ages since I heard about one, but maybe a new group formed.

    Thanks!
    Drifter
     
    #1 Drifter, Aug 23, 2013
  2. uart

    uart Senior Member

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    Hi drifter. That's a pretty normal situation if you actually are in neutral, it cant effectively charge the battery unless you're in "D/B" or "P". Since you weren't in "N" however, that makes it a bit strange.

    The reason why it can't charge in "N" is essentially because it requires generating torque at the wheels in order to generate any significant charging current. So perhaps you were sitting or creeping with neither significant accelerator or brake pedal applied, and it was therefore unable to generate the required electrical power without applying more torque than the ECU thought was safe (under the given pedal input conditions). It's possible that if you had applied firm brake pressure then it may have charged correctly. It's an odd one and I've never heard of it before, but that's all I can think of.
     
    #2 uart, Aug 23, 2013
  3. Robo

    Robo Junior Member

    Joined:
    Aug 19, 2012
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    Vehicle:
    2007 Prius
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    After traveling 3 hours and then going through the drive through, the battery stripes go to 3 or 4. I shut the car off, including lights, until its my turn at the window. Also, I very seldom use the air, and usually drive 55. My car has 198,000 miles on it and it runs fine.
     
    #3 Robo, Aug 23, 2013
  4. Drifter

    Drifter Member

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    I was definitely not in neutral but it is quite possible I hadn't been pushing the brake or accelerator for a couple minutes. I will remember to brake when in similar situations in the future just in case. I would have expected the battery to be in the two to three bar range in that situation and charged itself as needed, so it was scary to get a warning that it wasn't charging itself.
     
    #4 Drifter, Aug 23, 2013
  5. nh7o

    nh7o Off grid since 1980

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    Vehicle:
    2009 Prius
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    II
    I do notice that after I slowly come to a complete stop with only light pressure on the brake, there will still be arrows on the MFD showing energy going from Battery->MG2->wheels. If I press more firmly on the brake, those arrows will go away. The car is not moving, but there is a change of state in the hybrid control as a result of the increased brake pressure.
     
    #5 nh7o, Aug 23, 2013
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