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High Voltage Battery Drain?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by DrDeke, Nov 9, 2015.

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  1. DrDeke

    DrDeke New Member

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    Greetings,

    Have any of you ever had a situation with any generation Prius (or any other hybrid car, really) where you will park the car with the HV battery somewhere between 40 and 60% charged (as shown on the dashboard; I realize that is different than the true SoC), then you come back some hours later, start the car, and the indicated HV battery charge is much lower than when you left?

    If so, did you ever get it fixed or find out what was causing it?

    I am having that problem on my hybrid Ford Fusion, and I seem to have the dealer as well as the folks at fordfusionhybridforum stumped, but the gen1 ffh powertrain is very similar to that of the Prius, so I thought it might be worth a shot to ask here. I have owned the (2012 model year) car for just over two months, and this has happened five times so far with no kind of pattern I can see.

    Full problem writeup in the attached 2012FusionHybrid-HVBDrainProblem.pdf file.
     

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    #1 DrDeke, Nov 9, 2015
  2. bisco

    bisco cookie crumbler

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    it has been reported here to drop as much as two bars overnight. but i don't think it's a proBlem from an operational, mpg point of view.
     
    #2 bisco, Nov 9, 2015
  3. vskid3

    vskid3 Active Member

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    What's the temperature when you turn off the car and when you go back out to it? The battery can't put out as much power at high and low temperatures, maybe that's the cause of the issue.
     
    #3 vskid3, Nov 9, 2015
  4. DrDeke

    DrDeke New Member

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    The temperatures when this happened were mild; typically between 55 and 75 degrees Fahrenheit. Also, I guess I didn't spell it out in the original post, but we are talking 40-60% charged* when the car is parked, and 0% charged when I get out of work later that day and start it.

    (When I say "charged," I mean according to the dashboard indicator, which is proportional to but not indicative of the "true" state of charge of the battery pack.)

    When this happens, the ICE starts running immediately when I turn the key to "start" the car, which does not normally happen on this particular model. The ICE continues to run until the battery has reached at least 50% charged, even in driving situations (engine temperature acceptable, no cabin heat requested, vehicle stopped at a red light) where it would normally stop.

    Also, this is an all-or-nothing problem. When I come back to the car, the battery charge is either so close to the way it was when I left it that I can't tell it has changed at all, *or* on those five specific days, it is at 0%.
     
    #4 DrDeke, Nov 9, 2015
  5. vskid3

    vskid3 Active Member

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    Might be the battery doing a recalibration. Helps to keep the SoC display accurate. Some people notice it every once in a great while through the life of their hybrid, usually it happens more often when the battery is on its last leg (very common with Honda hybrids). It could just be that the Fusion hybrid does it more often than others.

    I'm not familiar with the battery reliability of the Fusion hybrid, but I know the Escape hybrid has a good track record (I don't think I've ever seen reports of one needing the HV battery replaced). Hopefully it's not a sign of the battery going out, though it should be under warranty unless you have over 100k miles.
     
    #5 vskid3, Nov 10, 2015
  6. mrbigh

    mrbigh Prius Absolutum Dominium

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    Battery recalibration sounds about right, but not so often.
    OTOH, Since we got some cold weather lately, my full battery charge dropped from 21 miles to 19 on my plug-in FFH.
     
    #6 mrbigh, Nov 10, 2015
  7. bisco

    bisco cookie crumbler

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    when you say 0% on the indicator, is that lower than allowed? on prius, the indicator never goes to zero.
     
    #7 bisco, Nov 10, 2015
  8. David Beale

    David Beale Senior Member

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    Sounds like there may be an electrical leakage problem either in your battery pack or perhaps the inverter. Not sure if the Fusion fully disconnects the traction battery like the Prius does.
    The Prius battery charge condition readout does vary a bit from shutdown in the evening to startup the next morning. It's usually only two or three "bars" on the charge indicator, and never (that I've seen or heard of) to "0" (no bars). It is caused by the battery temperature changing and sometimes by the system recalculating the charge level.

    Clearly, your car did still have some charge left, or the engine wouldn't have started.

    Dealer is no help?
     
    #8 David Beale, Nov 10, 2015
    Last edited: Nov 10, 2015
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