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Dead battery or fried electronics?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by trjd12, Mar 29, 2012.

  1. trjd12

    trjd12 New Member

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    Location:
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    Vehicle:
    2008 Prius
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    N/A
    I have a 2008 prius in which I purchased in 2010.

    Last week I had to get a jump. Saw a 10v reading in the diagnostic screen and purchased an Optimum Yellow Top Battery.

    Today I intended to install the battery. While trying to remove the first bolt (bolt holding the negative cable in place) I saw sparks/ static and immediately stopped. I waited a couple of minutes and tried the bolt by hand. It still required the wrench. I waited a couple of more minutes and tried the socket wrench again and there was sparks/ static. I stopped, left the bolt where it was and put the car back together with intent to try at a later time or have someone else do it. The cars dash still blinked like normal.

    Four hours later I went to start the car and the alarm went off (horn and hazards) it turned off fairly quickly and all electric ceased. So at this point I presumed that the battery was dead.

    I returned to my car two hours later, used the key because all the electric was out. While I was in the car the alarm went off again and I waited for it to go off, because I couldn't turn it off.

    I searched the posts and was not able to find anything related to the spark/ static, but did see threads dealing with electical problems as a result of improper procedure regardig the battery.

    I am looking for sugestions in my next steps...
    Should I be concerned with the spark/ static? :confused: (I thought that it could have been attributed to my hand rubbing against the carpet interior while using the socket wrench)
    Should I try to jump start/ charge the battery?
    If I do, should I fear electronic failure due to the static/spark?
    Proceed with the change in battery - I was going to do this when I thought the battery was dead, but the alarm has since went off -So wouldn't that mean the battery is not dead?)
    Tow it to Toyota for expensive diagnostic and repair? :(

    Help me with my presumed Catch 22. Thank you for your time!
     
    #1 trjd12, Mar 29, 2012
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Vehicle:
    2015 Prius
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    Two
    Regarding any static discharge, I suggest you touch bare metal on the body of the car before you start, to discharge whatever stray electricity may have accumulated on your body.

    There may be a spark as you remove and reconnect the negative battery cable. Don't worry about that. There is some current flow because some of the ECU circuitry remains powered up at all times.

    Definitely, replace the 12V battery now. After you have replaced the battery, if you still are having a problem then it may be necessary for you to have the car towed. However towing would be a premature action, until you've tried without success to replace the battery. Good luck.
     
    #2 Patrick Wong, Mar 30, 2012
    2 people like this.
  3. KK6PD

    KK6PD _ . _ . / _ _ . _

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    1 listen to Patrick, 2 listen to the other Patrick, me, just make sure when you put in the new battery you get Positive and Negative correct!
    Red is + Positive, Black is - Negative.
    DO NOT REVERSE THEM!!
    Hook the Red battery lug to the + terminal first, tighten down securely, do not over tighten. When you attach the Black - Negative lug you will again probably see a small spark again. DO NOT FREAK, it's just the current draw from the cars standby systems regaining power again, just securely push the neg terminal in the post and tighten, do not over tighten. If you have no further problems, you should be able to sit and start the car as normal.! You can do this! Then get yourself a beer! :D
     
    #3 KK6PD, Mar 30, 2012
    2 people like this.
  4. seilerts

    seilerts Battery Curmudgeon

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    You've left the car in a state where the battery negative is poorly connected. This means high resistance/intermittent connection, and very, very bizarre electrical behavior.

    There is normally arcing when disconnecting the negative. I don't like that either. I've taken to attaching a jumper from the negative to the body and then unbolting the ground from the body. Then remove the jumper.

    All you need to do is finish the job. If you want to avoid arcing, connect a jumper to the negative post while removing the ground attachment to the body, then remove the jumper.
     
    #4 seilerts, Mar 30, 2012
    3 people like this.
  5. qbee42

    qbee42 My other car is a boat

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    When disconnecting the battery, it's better to do it decisively. Each time you wiggle it around and cause sparks you are creating transient voltages in the electronics. Computer systems don't like wobbly voltages; they much prefer clean transitions, where the power-on sequence can correctly complete.

    The long and the short of it: the negative cable will spark a bit, but just take it off and be done. Don't fool around.

    Tom
     
    #5 qbee42, Mar 30, 2012
    1 person likes this.
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