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Battery Charging Issue?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by scottwg, May 19, 2016.

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  1. scottwg

    scottwg Junior Member

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    My car coded a dead hybrid battery after replacing it with a Dorman two years ago (to their credit they replaced it that day no questions asked by the way). But now I am wondering if it was the battery or the car. After replacing the hybrid and going to start the car, I noticed not only was my 12V dead, it was at 5.5V. I took a new battery and just set it in the car on cables so I could make sure the car drove. It did and I drove until the hybrid battery mostly charged. On the way back to my house, the charge went almost completely to zero. But I do not watch it often enough to know if that is normal. But by the time I reached my house I was charged to the next to last green line of full charge. And when I disconnected the spare 12V, not only was it still 13V, but my previously dead battery was surprisingly just over 12V. Does anyone see any problems? No codes. Everything seemed just fine. 2006 by the way with 222K
    Thanks,
     
    #1 scottwg, May 19, 2016
  2. JC91006

    JC91006 Senior Member

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    Just take out the old 12v (as it's dead), and put in the new 12v. Drive it for a day and see what changes
     
    #2 JC91006, May 19, 2016
  3. S Keith

    S Keith Senior Member

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    What codes?

    A bad 12V can cause an HV battery code; however, it usually throws in several others for good measure that make you say, Wth is going on? Is my car exploding? Has every ECU failed? Is it being swallowed by a crack in the space-time continuum?

    The 12V exists solely to power the various ECUs prior to start. Once the car is started, the HV system charges the 12V and provides all 12V power.

    The issues I see are:
    1. A 12V battery that has discharged to 5.5V and is more than a few months old should be replaced. It has been permanently damaged and lost capacity. It's not worth the hassle of recharging and hoping its good. If you really want to evaluate it, charge it at 4A max until it registers full, then let it sit for 24 hours. Take it to an auto parts store and have them load test it.
    2. It is no surprise that your old dead battery was at 12V. 12V is still pretty much dead, but it had been subjected to a 14V charge for the duration of your drive as well as being in parallel with the good battery.
    3. The HV battery charge should only drop low if you are climbing hills without opportunity for regen and/or you are blasting your A/C and are in stop-and-go or waiting in drive-thrus, etc., i.e., lotsa A/C, very little gas running.
    If you didn't meet the conditions in 3, I would be very worried that you have another failing or at least weak battery from Dorman. I recommend you run the discharge test in my signature in the morning on a cold engine and estimate the state of health.
     
    #3 S Keith, May 19, 2016
  4. scottwg

    scottwg Junior Member

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    All great advice. Thanks. I will check it in the morning and get another 12V. Too bad they are so ridiculously expensive.
     
    #4 scottwg, May 19, 2016
  5. JC91006

    JC91006 Senior Member

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    You can get a optima yellow top on Amazon for $147.xx. If you use it for 5 years, it would only be $30 a year overall cost
     
    #5 JC91006, May 19, 2016
  6. S Keith

    S Keith Senior Member

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    Would still like to know the codes.
     
    #6 S Keith, May 19, 2016
  7. scottwg

    scottwg Junior Member

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    Thanks. Great advice. I will do the battery test tomorrow and replace the 12V
     
    #7 scottwg, May 19, 2016
  8. S Keith

    S Keith Senior Member

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    [S Keith whispers quietly... "what were the codes?"]
     
    #8 S Keith, May 19, 2016
  9. scottwg

    scottwg Junior Member

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    Sorry. The only code I know I got was "hybrid battery" I do not know the number and now it is lost I guess (?) And that is the battery I got off of Amazon. I got it a year ago or so.
     
    #9 scottwg, May 19, 2016
  10. S Keith

    S Keith Senior Member

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    [S Keith recedes quietly into the shadows]
     
    #10 S Keith, May 19, 2016
    jadziasman likes this.
  11. JC91006

    JC91006 Senior Member

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    If you got the optima from Amazon a year ago, just call Amazon and they'll send you a replacement for free
     
    #11 JC91006, May 19, 2016
  12. scottwg

    scottwg Junior Member

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    (HA!)

    JC, if you are right about that battery then you will have made my day. I am going to check now and see how long it has been.

    Thanks again
     
    #12 scottwg, May 19, 2016
  13. JC91006

    JC91006 Senior Member

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    You can call them up to 2 years for a replacement. That's their warranty
     
    #13 JC91006, May 19, 2016
  14. scottwg

    scottwg Junior Member

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    Right now I am chatting with them. It has been less than two years but when I hit the replace option it said it was not eligible due to shipping issues. I am checking now
     
    #14 scottwg, May 19, 2016
  15. JC91006

    JC91006 Senior Member

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    Only the representative can do the replacement. You can't click on "replace". You should still find out how a 1 year old battery drained so badly
     
    #15 JC91006, May 19, 2016
  16. scottwg

    scottwg Junior Member

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    I am getting a refund right now. Great advice. You just saved me a bundle!

    The only thing that has been strange about my car is a hesitation that happens just before the engine is supposed to start. Sometimes I have no power at all at a complete stop because it seems like only the electric drive is coming on and the engine is being called for but not engaging in time. I have a thread about it but never got any really good advice. I checked a bunch of good ideas, but nothing was ever found. There were originally "Engine failed to start" codes (no numbers, sorry S Keith). But since they went away and it has been driving OK, I stopped worrying about it. It never coded again and I have just learned to live with it. It is so subtle, I started to wonder if I had made it all up in my head
     
    #16 scottwg, May 19, 2016
  17. scottwg

    scottwg Junior Member

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    BTW. It seems to happen only when the engine is cold. In the morning mostly
     
    #17 scottwg, May 19, 2016
  18. JC91006

    JC91006 Senior Member

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    1. Why are you getting a refund? You need a new battery!
    2. Try cleaning your throttle body. I think slight hesitation is normal right at start up with a cold engine
     
    #18 JC91006, May 19, 2016
    S Keith likes this.
  19. scottwg

    scottwg Junior Member

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    That is one of the things I did. I down right polished the throttle body (it really was not that dirty) and the MAF. It never made a difference.

    I will just use the refund to get a new battery. I have another car
     
    #19 scottwg, May 19, 2016
  20. scottwg

    scottwg Junior Member

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    I would have thought it was normal, and it has not been as badly lately. But it scared the hell out of me one morning when I tried to pull out in traffic and my car only wanted to go 5mph after flooring it!
     
    #20 scottwg, May 19, 2016
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