At what point do you replace the 12v battery?

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by mikefocke, Jul 1, 2016.

  1. Cactus Chuck

    Cactus Chuck New Member

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    I did not test the voltage of the battery. Not sure how.
     
  2. dig4dirt

    dig4dirt MoonGlow

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    Just asking because if purchased from an auto parts store or anywhere.. It may have been sitting and lost voltage.

    Figuring that out first may save $$$$ and headaches in the future

    A 5 or 10 dollar voltmeter can test it.
     
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  3. Cactus Chuck

    Cactus Chuck New Member

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    I do get the ready light for the first 5 seconds of the start cycle.
    Some:eek:_O
    • C1259
    • P3000
    • P3191
    • P3190
    • P0121
    • P0012
     
  4. Mendel Leisk

    Mendel Leisk 'Orrible Oracle

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    You bought this car non-running? Any more details you can divulge?

    I'm just guessing someone either ran down the the 12 volt, or ran it out of gas, and then ran the hybrid battery down, into dangerous territory, trying in vain to start it.

    The first 2~3 of those codes are pointing at the hybrid battery. Considering that and the 1 bar displayed in hybrid battery state of charge, it looks like the hybrid battery is depleted, beyond normal levels. I think dealerships can get in a special charger for those cases??
     
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  5. Raytheeagle

    Raytheeagle Senior Member

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    Have you cleaned the MAF sensor and throttle body:whistle:?

    Might be the next things I would look into given the P3190 and P3191;).

    Good luck and keep us posted(y).
     
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  6. Cactus Chuck

    Cactus Chuck New Member

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    @ChapmanF Thanks for the explanation. It really answer the question I had. (y)
     
  7. Cactus Chuck

    Cactus Chuck New Member

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    I'll check that next, Thanks!
     
  8. Cactus Chuck

    Cactus Chuck New Member

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  9. Cactus Chuck

    Cactus Chuck New Member

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    @Mendel Leisk Yes, that is part of the reason I bet on it...I just hoped there was an easier way to recharge the battery. There is a business idea. Mobile battery charging haha
     
  10. fuzzy1

    fuzzy1 Senior Member

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    Alternate idea: put a 12V battery tender / maintainer on it overnight. The tender should have an indicator light telling when the battery is (nearly) fully charged.
     
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  11. Cactus Chuck

    Cactus Chuck New Member

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    Update: Tested Battery with voltmeter 12.2V and with my Actron reader with the ignition on ACC 9.8
     
  12. jzchen

    jzchen Senior Member

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    Post 106 has the instructions. Item #2 in that document if I recall what I just reread.

    When charging the battery heed the warning on maximum charging current. That is the maximum charger's rated current/Amps. The document says 4-5 amp range, but the original battery notes a maximum of 4.2 A. I have a Duracell 4 Amp unit that I got recently, last few months, at Costco if you need one.

    My parents' battery fell within the recharge range after repeated charging and testing. I replaced it for good measure.

    I'm still very happy with the eBay/Chinese LiFePO4 battery that is in there now, even though it did not fit perfectly. (I made the seller aware of the issue and hopefully resolved by now). One year 4 months and still going strong. 9.x lbs vs 28 lbs for the original....

    moto g(7) power ?
     
  13. fuzzy1

    fuzzy1 Senior Member

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    As a retired electrical engineer, I once designed many computer-type boards of that sort in other equipment. In that era, all the digital logic worked at 5V, maybe needing 6 to 8V at the power supply inputs depending on how they were designed. Since then, the industry as produced numerous other logic families meant to run at lower voltages, and voltage regulators meant to operate with lower input-to-output voltage drops.

    While it is possible that some such digital logic equipment and error codes can't be trusted when their 12V supplies falls to 11V or 10V, it will happen only from gross engineering incompetence. Major design FAIL. If participating in a technical design review, I would shred them mercilessly. There is simply no excuse for it.

    This commentary doesn't apply to the overall work operation of the 12V appliances and accessories and devices themselves, which may well need something close to the full 12V to properly perform their intended work functions. But their basic digital controls, program boot up, fault detections, and error reporting should reliably operate at much lower voltages. In this era, there is no reasonable excuse for not doing so. There was hardly any excuse even three decades ago.
     
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  14. sam spade 2

    sam spade 2 Senior Member

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    NOT GOOD.
    Time for a new battery.
    And then check the voltage with it "running" too.
    That will verify that the charging system is working.
    It should be between 13.5 and 14.5 in the READY mode.
     
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  15. sam spade 2

    sam spade 2 Senior Member

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    There is SUBSTANTIAL evidence provided by real world experiences that say it happens frequently.
    Whether or not it "should" is a theoretical discussion.

    A resistor matrix to get the 12-15 V input down to 5-9 volts that you actually need is a lot cheaper than an actual voltage regulator.
    And these days it seems like EVERYTHING is about cost.
     
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  16. ChapmanF

    ChapmanF Senior Member

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    All of the substantial evidence provided by my real-world experiences aligns with fuzzy1's notes. 5 volt logic circuits have a very narrow range of operating voltage (feed one 5.25 and you'll start getting arithmetic errors, I've had to deal with such situations at work). When designing for a car environment where even the anticipated normal range of supply voltage is "somewhere between 11 and 15", nobody uses "a resistor matrix" to get their tightly regulated 5 out of whatever is coming in. They use on-board voltage regulator modules sitting right next to the logic circuits that need them. Such VRMs are off the shelf components. Skim the "detecting conditions" for some of the documented diagnostic codes in the Prius repair manuals and you will see a few that refer to the VRM output, aha!, going outside a narrow range, 4.75 to 5.25 ish, IIRC. I've posted examples before but don't have time right now to search them back up.

    Those typical VRMs will require a headroom of a volt or two to do their jobs; one with a 5 V output will be struggling when it's getting less than about 7 in. That aligns quite well with my experience of when a Prius will become un-READYable. Fix the power problem and it's a car again. It may have some codes logged that specifically tell you certain voltage limits were crossed; it won't have codes that were made up.
     
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  17. fuzzy1

    fuzzy1 Senior Member

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    It is also a quality control discussion, and a business history discussion. Compare the W. Edwards Deming school of quality control (post-war Japan) vs. that of Alfred P. Sloan (General Motors). Japan ate our lunch. Sloan's version of GM no longer exists, now just a ghost of history.
    It is cheaper only on the initial production line. Product failure and warranty and support expenses more than eat up all the initial bean-counter savings.
     
  18. ChapmanF

    ChapmanF Senior Member

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    It's also kind of a wasted discussion. There's no universe where Toyota used resistor networks to make the +5 in their ECUs, except the one Sam inhabits.
     
  19. sam spade 2

    sam spade 2 Senior Member

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    Insults accomplish nothing useful.

    There is, however, a universe in which designs include not a true voltage regulator but what is more properly called a "voltage limiter", some of which don't maintain a good constant output as the input drops much below the design parameters.

    The fact remains that all kinds of "strange" stuff happens when the 12 V battery gets down to what most unskilled owners......and some who think they are skilled.....would consider "just a bit low".
    Like 12.0 volts with no load, for instance.

    And finally.......you don't really KNOW what the internal design of the computer boards IS.
    Likely that you are right, but that doesn't really add anything useful to the discussion.
     
  20. fuzzy1

    fuzzy1 Senior Member

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    ... so why do you make them?
     
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