Brand new 12V battery; still dying

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by SamusAran, Mar 29, 2017.

  1. SamusAran

    SamusAran New Member

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    For a couple of months now my 2008 has been dying with increased frequency. I've had to do a lot of jumping.

    Sometimes when I shut the car off and open the door it beeps as if the key is in it but its not. It's not the doors or the lights. Sometimes the master warning light comes on. Sometimes nearly every warning light comes on.

    I had the battery checked and it was bad so I bought a brand new Optima one. It started up fine but a couple hours later it was dead. I jumped it and drove around town then later this afternoon it was dead again.

    It looks like although the battery was bad, there is another underlying problem that's draining the battery (bad inverter from jumping?). If anyone has any experience with this I'd really appreciate it. I've seen a lot of the same symptoms on here but the solution is never updated on any of the threads I've read. Thanks!
     
    #1 SamusAran, Mar 29, 2017
  2. JC91006

    JC91006 Senior Member

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    You should check the car for codes, the warning lights mean there's a problem.

    In the meantime, charge the 12v fully before you use it again
     
    #2 JC91006, Mar 29, 2017
  3. cobaka

    cobaka Junior Member

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    And check the 12v battery's ground cable; negative post to rear body wall. I just went thru this. The ground was not tightened, and was very loose. I removed the 12v, charged it was 24 hours, and put it back, with the cable tightened. After 2 batteries doing the same as yours, it was a ground cable.

    Posted via the PriusChat mobile app.
     
    #3 cobaka, Mar 29, 2017
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  4. andrewclaus

    andrewclaus Active Member

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    Do you have a volt meter to check the battery?
     
    #4 andrewclaus, Mar 29, 2017
  5. cobaka

    cobaka Junior Member

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    #5 cobaka, Mar 29, 2017
  6. Jmack111

    Jmack111 Member

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    #6 Jmack111, Mar 29, 2017
  7. dolj

    dolj Senior Member

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    To that end, what is the voltage when the car is READY?
     
    #7 dolj, Mar 29, 2017
  8. SamusAran

    SamusAran New Member

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    I don't have a volt meter. I purchased and had the battery installed today though. I started it immediately after installation to see if it worked and shut it off. About 2 hours later I tried again and the dash lights went crazy for a second then the car wouldn't start. I have a habit of leaving the smart key in the cup holder when I'm home but could the smart key really discharge a brand new battery within a couple of hours (assuming the battery came fully charged)?
     
    #8 SamusAran, Mar 30, 2017
  9. cobaka

    cobaka Junior Member

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    #9 cobaka, Mar 30, 2017
  10. andrewclaus

    andrewclaus Active Member

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    If you're going to try to work on this yourself, an inexpensive digital volt meter will be one of the important tools. Harbor Freight Tools often gives them away, literally, with a coupon. A set of small metric combination wrenches will be another, to allow you to check and clean the negative battery connections.

    And as mentioned above, if the check engine light is on, something has failed. You need to get the codes or we're just guessing. Some auto parts stores will scan for free, but they use generic scanners that can miss some critical Prius-specific codes. It would be a start, though, for no cost. You may need to pay the dealer's diagnostic fee, or purchase a scanner that's programmed for the Prius (Mini VCI for example).

    I agree, the key did not cause this problem.
     
    #10 andrewclaus, Mar 30, 2017
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  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Stop doing that, recharge the battery with a smart charger, see how it goes.

    Also, no matter how secure your situation is, that's like leaving signed blank checks lying around.
     
    #11 Mendel Leisk, Mar 30, 2017
  12. fuzzy1

    fuzzy1 Senior Member

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    #12 fuzzy1, Mar 30, 2017
  13. andrewclaus

    andrewclaus Active Member

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    #13 andrewclaus, Mar 31, 2017
  14. valde3

    valde3 Senior Member

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    But OP can still use the MFD volt meter to check that charging voltage (voltage when Prius is READY) is about 13.8V or more.

    If it’s not then maybe there is a problem with inverter converter. Are there any fault lights on when READY?
    If charging voltage is fine then maybe there’s a problem with battery cables. First check that terminals are tight on the battery. If those are fine then Prius battery ground cable can have problems in couple of areas:
    -Connection between body and cable terminal (see if it’s rusty or lose)
    -Crimp between the cable and cable terminal (see if corroded and/or lose)

    If all of those are fine then it either is parasitic draw or bad/empty 12V battery. Battery being empty or going bad can be caused by leaving the key in it the Prius. If you have to leave the key in it turn the smart key system off with the button bellow steering wheel.

    You need a current meter to check for parasitic draw.
     
    #14 valde3, Apr 1, 2017
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