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Please help 12v battery problem

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Na3eem, Sep 2, 2015.

  1. Na3eem

    Na3eem New Member

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    Hello all
    3 days ago I bought a used 2009 Prius, the car was totally fine until today.
    went down to the food mart in a gas station ..went back, and the car wont start. Lights start to flash and then it got dimmer, dashboard light went off but the check engine light.
    I thought it was the 12v battery, I jumpstarted it and the car started but with the red triangle light and the check engine light. drove it home switched it off (the warning lights were on all the time back home). tried it to switch on again but nothing happened everything is dead even the door locks.
    please advice me what can i do.

    Thank you
     

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    #1 Na3eem, Sep 2, 2015
    Last edited: Sep 2, 2015
  2. Beachbummm

    Beachbummm Senior Member

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    replace the battery first
    read the error codes and reset them
    hope for the best.
     
  3. edthefox5

    edthefox5 Senior Member

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    Classic scenario. Prius sits on car lot for days maybe weeks and 12 volt battery dies from not driving it.And sits dead for days sulphating. Prospective buyer comes along and car is jump started and away you go with a battery on its last legs.

    Replace the battery and in doing so by removing the negative cable it will clear the codes. Hope and pray they don't come back.

    Note to all used DEALER or CAR LOT or AUCTION Prius buyers. Replace the 12 volt battery as soon as you get home no matter how well it tests.
     
  4. Lucifer

    Lucifer Senior Member

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    As you had no idea that the 12v only lasts five minutes when uses in accessory mode...
    Your 12v is toast, don't buy one from the dealer get an optima yellow top, but...did you fry your inverter when you jump started?
     
  5. JimN

    JimN Let the games begin!

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    He didn't. If he fried the inverter he wouldn't have been able to drive home.

    When my 12v died there weren't any idiot lights. The symptoms were: door didn't unlock, interior lights did not illuminate, dash was dark.

    With the fob in the slot, the car booted up on the third attempt. I don't remember any idiot lights.

    If the 12v is 6 years old it is probably weak to dead. It's easy enough to check the voltage so there's no reason to guess.

    If buying a battery at the auto parts store ask them to read the codes. Make sure the battery is fully charged. Using a BatteryMinder or trickle charger will prolong the life of the battery. Learn to do your own diagnostics. Buying a good scan tool is a wise investment. Why pay someone to do something if you are capable?
     
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Speaking is Scan Tools, there's a new diagnostic tool for batteries now, compares actual CCA to spec'd. Solar and CTEK are a couple of options, both about $80~90.

    Google "12 volt battery diagnostic tool" or similar.
     
    #6 Mendel Leisk, Sep 2, 2015
    Last edited: Sep 2, 2015
  7. bisco

    bisco cookie crumbler

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    a new battery should read 13 volts before installation, but 4 hours after charging.
     
  8. Dino33ca

    Dino33ca Member

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    Hi folks, I just did the battery test which resulted in 12.4v on initial startup. Then 12.1v when I hit the power button without the brakes, however when I turned the lights on the battery dropped to 11.5v. When I powered her up I get 14v. Time for a new battery? It's not even 3 years old yet but it has been run down a few times. Thanks...
     
  9. bisco

    bisco cookie crumbler

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    i think so.
     
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  10. edthefox5

    edthefox5 Senior Member

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    11.5 is almost dead Jim. if it was a regular car it would have trouble turning the starter over and you'd be like uh oh new battery time. This battery only has to close some relays and boot up a few ECU's. No warning just stranded. Actually it did give you as warning.....the 11.5.
    :)
     
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  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Been down a few times, not so good. Have you ever hooked up a charger? If not, at this juncture it's likely best to replace it.

    There's a lotta things you can do to preserve the next one. First and foremost: read up on battery maintenance. A digital multimeter is handy, by no means definitive, but helpful. And useful for a lot of other stuff. A smart charger in the 4 amp range is good to acquire. You can use it say once a year, even just for maintenance.

    Last but not least, turn off all the accessory lights you can live without, don't listen to the radio in accessory mode, don't leave doors or hatch open any longer than needed.
     
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  12. Dino33ca

    Dino33ca Member

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    Thanks guys. I've also got all brake light warnings coming on including emergency brake light. Mpg has taken a big hit, and the car seems to be having some difficulty charging up the mfd bars. I've been driving between two and four bars for the most part. The hybrid battery is not heating up, no fan coming on, no wild fluctuations in the mfd bars and it's driving up hills okay. Another weird thing which I've never seen before is that when it's in drive and I'm at a complete stop with the brake pedal fully pushed down the battery on the mfd is shown as discharging.

    This morning I took the negative battery cable off for an hour, put it back on, and the brake light warning come on immediately. However, when I test the battery again it seems to be stabilizing at 12v when I hit the power button with the lights on. I then put the windshield wipers on full tilt and opened and closed the windows and withing ninety seconds or so the battery drops down to 11.4v.

    Whats strange is this all started after I blew a front tire on the highway and ended up putting on my winters in the front temporarily. I did an oil change as well and then the warning lights come on.

    Well, I figure I'll save the one hundred dollar assessment from the dealership and just go ahead and put in a new 12v battery and keep my fingers cross. Thanks again...
     
  13. ChapmanF

    ChapmanF Senior Member

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    Do you happen to know whether your winter tires have the same revs-per-mile as the tires in back? You do know the car monitors wheel speed at all four corners? If the braking/skid control computers are getting a constant signal that the front of the car is traveling a different speed than the back, it would not be surprising to log trouble codes and go into a failsafe mode.

    Whether at the dealer or not, do you have any plans to find out what trouble codes your computers are trying to tell you about? That often will tell you a lot that is worth knowing.

    -Chap
     
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  14. Dino33ca

    Dino33ca Member

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    Thanks Chapman, the winter tires are 195/65 and all seasons in the back are 185/65. I'll change the winter tires off right away and see if that helps. The Ultraguage that I have is only reading one code and that's the p1121 (control valve) that I already know about. That was dumb of me! I'm surprised when I unplugged the 12v battery for an hour yesterday that the lights didn't come off. Oh well, off to change some tires....
     
  15. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The tire size mix is the cause of the skid control ECU warning lights being on. You must use the same tire size at all four wheels.

    You have at least one other, and perhaps two other problems: You need to replace the engine coolant valve and probably need to replace the 12V battery.
     
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  16. Dino33ca

    Dino33ca Member

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    Thanks Patrick. I'm just changing the tires now. I was really surprised to see the difference in how the volts were measured as compared to before and after I pulled the negative cable off the battery. I do have the coolant valve on hand, I've just been too busy (lazy) to change it. Thanks so much guys.