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Traction Battery starting to fail?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Susan5s, Jun 19, 2010.

  1. Susan5s

    Susan5s Junior Member

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    I'm sorry if I'm repeating a thread that's already out there but I've searched all the Gen II forums and haven't found exactly what's going on in my 04. Car has 106,800 miles and for the last several weeks, when I'm stuck in traffic, like trying to get into the Lincoln or Holland Tunnel, the battery seems to go from 7 blue bars to two pink bars within five to seven minutes. Used to be that it took 3 five-minute bars of traffic, running fully electric at 100 mpg, to then go down to 2 pink, when the ICE would run and charge the battery. Today the battery indicators went down to 2 pink after sitting in traffic with the AC on and stayed there for the remainder of the time we sat in traffic - another 45 minutes or so. The ICE would run at idle sometimes, but didn't seem to bring the battery back up unless we were really moving. A couple of times I held the brake with my left foot, revved the engine with my right, and that seemed to bring the battery up a couple bars. After we finally got going on the highway, the battery recovered. I got no warning lights, no triangles. But I'm wondering if these are symptoms of the battery failing. Time to get it tested at the dealership?
     
  2. Bob64

    Bob64 Sapphire of the Blue Sky

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    Sounds normal to me. Perhaps you didn't have the A/C on when you did that before.

    In case you didn't know: the A/C runs off the battery... so having the A/C on really eats the battery charge.

    The symptoms of the battery dying is basically parking it in your garage at normal blue charge, then starting it up next morning and it showing red. Rapid changes in battery charge when you don't use it.
     
  3. Susan5s

    Susan5s Junior Member

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    Thanks, Bob. In 6 years of owning this car, I've run into bad traffic getting in and out of NYC countless times in all kinds of weather. Knowing that the A/C runs off the traction battery, I did turn it off when it was clear we were going to be sitting/crawling for an extended period, and then saw that the battery was down to 2 red bars in only five minutes.

    I'll keep an eye now on the battery state at shut off and startup. Thanks again for the info!
     
  4. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Are you still on the original 12v battery? Some of the ways the 12v battery fails involve the HV battery trying constantly to recharge it, which draws a LOT of juice from the HV battery.

    In 'normal' cars you hear the 12v battery slow down when starting the car, but a Prius does not use the 12v to turn the engine, so you need to be alert to other symptoms. One easy way to test is to get in your car after sitting a couple hours and turn on ACC (no foot on brake) and try the power windows, then start the car and try the windows, if they are much slower in ACC, I would have the 12v battery tested.

    The Prius uses an odd sized battery so you have to get it from the dealer or use a conversion kit.

    12 Volt (12v) Toyota Prius Auxilary Battery for 2004, 2005, 2006, 2007, 2008, 2009 and 2010 with installation kit
     
  5. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Get your Prius into "Accessory Mode" - Press the power button without touching the brake pedal.
    Put the MFD into "Maintenance Mode" - Press and hold the "Info" button on the MFD while turning the headlights on and off 4 times.
    Press the "Menu" field on the screen.
    Press the "Display Check" field.
    Press the "Signal Check" field.
    The 12v battery voltage will be one of the items listed, it should be above 12 volts. If it is lower, either the battery needs replacement or the charging system is not functioning correctly - see step 7.
    Put a small load on the battery by pressing the power button again without touching the brake pedal. The voltage should stay above 12v. If it drops significantly, you need a new battery
     
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  6. djasonw

    djasonw Active Member

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    No need to worry. I think what you're seeing is normal behavior. I have the same model year and with the high temps/humidity the AC does draw a considerable amount of power so it makes sense that at idle it will drop down to two pink within that time frame. Mine functions quite similarly and I am not concerned at all.
     
  7. Susan5s

    Susan5s Junior Member

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    Jimbo, Thanks for your suggestion to check the 12V. I just went out to the car and followed your steps. At first the readout was 12.1V. Then when I hit ACC again (no brake) it briefly went to 11.9, then up to 13 or 14, and back down to 12.1. Seems to me the 12V is probably OK. BTW, the power windows on my car have only ever worked if the the car is in Ready mode, not in ACC.

    Gotta love the maintenance screens - they feel like the hidden Easter Eggs we used to find in MS Office programs.

    Djasonw - thanks for the reassurance. Glad this isn't unusual. What raised the concern really is the change of behavior. It used to take the battery 15 minutes of idling or crawling in traffic with or without A/C to get down to 2 pink bars. Now it's only 5 or so minutes. Have you also noticed this kind of change?
     
  8. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    My understanding is, anything under 12.4 on that test is a sign of a weak 12 v battery, I really would pursue that idea.
     
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  9. Susan5s

    Susan5s Junior Member

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    I'll call the dealership on Monday. Thanks again!
     
  10. usbseawolf2000

    usbseawolf2000 HSD PhD

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    My experience with or without A/C is different. HV battery runs down quicker with the A/C on.
     
  11. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    12.1v is too low for a 12v battery. Also the MFD is known to be off quite a bit. I dont expect everyone to own a great multimeter, but if you buy the $10 version from RadioShack it will give you a much more accurate readout. Maybe even craigslist in your area, just see if anyone has a multimeter.

    But assuming the 12.1v is the actual readout, then your battery is toast. Replace it.
     
  12. Susan5s

    Susan5s Junior Member

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    Thanks everyone! I'll be on the phone Monday to get the battery tested/replaced.
     
  13. Helio

    Helio Member

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    I too recently noticed my traction battery discharging faster and my mileage slowly decreasing. I also noticed that after I turn the car off the windows don't go up as fast as when the car is on. I began to wonder if it was the 12 v battery, especially since I had an inexplicable dead battery after the car being parked for only two hours once last winter (there were no interior or exterior lights left on or any other explainable battery draws). I accessed the hidden eggs and saw that after the car was turned off for a few minutes the battery was in the 10 v range and about 9.9 v when I apply the brake. I quickly ordered a new battery from eLearnAid.com, it's on the way.
    BTW, I could not find a less expensive price than what eLearnAid.com has, and the shipping was free!!!