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2010 - Sudden 12V Battery Failure

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by jdcollins5, Jan 25, 2015.

  1. Easy Rider 2

    Easy Rider 2 Senior Member

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    What kind of charger do you have ??
    It is NOT necessary to have a "special" charger for an AGM battery.
    If your charger is an automatic tender type charger less than 10 years old, it will be just fine.
    If it is not automatic, then disconnect it shortly after the current goes down near zero.
    If you have no way of telling when the charging is done, that is no light and no meter, then junk the charger.
     
  2. Former Member 68813

    Former Member 68813 Senior Member

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    ^this.

    no, this not sticky worthy. for starters it lumped the wet and AGM together. not correct, AGM show slightly higher voltage.

    better to leave hood open, this way nothing is disturbed when you take measurement at the "jump" terminal, assuming you park in a garage.

    12.85V 30min after long drive
    12.8V next morning
    over 4 year old OEM battery 50F ambient temp (garage)
     
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  3. GregP507

    GregP507 Senior Member

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    In an ideal world, you would check your battery every 10 minutes, and deliver exactly the right amount of charge. Repeat this routine for 5 years, and your battery will still be nearly as good as new.

    Or you could use a battery-minder and have all of this done automatically.
    ;)
     
  4. jdcollins5

    jdcollins5 Senior Member

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    The charger is an older 2/10A manual charger with meter. I will have to watch until meter goes to zero.

    The first time I ran out of time before charger current went all the way to zero.

    Do you ever post any helpful information ?
     
    #64 jdcollins5, Jan 29, 2015
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  5. GregP507

    GregP507 Senior Member

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    What's your point, exactly?
     
  6. Easy Rider 2

    Easy Rider 2 Senior Member

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    Not true. Look again.

    The second set of tables has a section for AGM/GEL that shows higher voltages.
    It does not show specific gravitys because you can't extract a sample of the electrolyte to test.

    The tables are a bit confusing as it shows only spec. gravity for "maintenance free" wet cell types.
    Maybe the voltages would be the same as the top table ??

    AND.......it's a LOT better than anything else I've seen.
    Arguing over inconsequential nits is counter-productive.
    We are not teaching a course here in advanced battery engineering and design.

    It likely won't ever get to exactly zero. It should "settle" at a mark or two above that.
    Once it gets down to .2 or .3 on the 2 amp scale and stays there for a couple of hours, then it's done.
     
    #66 Easy Rider 2, Jan 30, 2015
    Last edited by a moderator: Jan 30, 2015
  7. Mendel Leisk

    Mendel Leisk Senior Member

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    So yesterday, after a drive, ours measured 12.75 volt. Prior to the drive it was around 12.45. Then, first thing this morning, popped hood and measured again: 12.49. Left everthing as-is, went back in the house, put my fob on a desk. After about 20 minutes, went back out and remeausred, now it's reading 12.59, a significant jump.

    This is with a decent Milwaukee TRMS meter. Interesting.
     
  8. Former Member 68813

    Former Member 68813 Senior Member

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    so then why do you argue over it?

    if you open the drivers door to open the hood, the car goes through brake pressurization that eats electricity from 12v battery, right?
     
  9. GregP507

    GregP507 Senior Member

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    I haven't done a test, but lights should shut off after being left on for a certain period if time. Personally, I like to double-check, just like leaving the stove on, or the water running.
     
  10. jdcollins5

    jdcollins5 Senior Member

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    That is interesting. I will have to try that tomorrow before doing the parasitic drain test which I will leave the fob inside while doing any way.

    I have my meter in the cargo area and have been using the remote unlock to unlock the cargo door. I have not been opening the driver door so the brakes should not be pressurizing. Since I am not walking to the driver's door the dome lights are not coming on like they do when you get close to the driver door. The car should be recognizing that the fob is close by though and waking up the SKS.

    I tested mine again this morning and it was at 12.6V at 50F, with my fob in my pocket. I want to think that this is pointing to the battery never being fully charged.

    I am interested in the parasitic drain test so I can possibly eliminate this as an issue.

    I also have a BatteryMINDer on order so that I will be able to safely fully charge the battery.
     
  11. Mendel Leisk

    Mendel Leisk Senior Member

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    I always open front passenger door, hop in, and reach across to pop the hood. Not just to avoid triggering electrical load, but to stop the system pressurizing every time I lift the hood. Also, for the between first and second measurement I left the hood up, just let everything sit.

    I appreciate this degree of attention to the 12 volt is overkill for a daily driver. Our car often sits multiple days though, and the battery's over 4 years old.
     
    #71 Mendel Leisk, Jan 30, 2015
    Last edited: Jan 30, 2015
  12. jdcollins5

    jdcollins5 Senior Member

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    Find attached two battery charging tables from the BatteryMINDer that I just purchased.

    In the second table it shows the voltage increase necessary for the AGM versus the Wet Cell battery.
     

    Attached Files:

  13. CR94

    CR94 Senior Member

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    Excellent plan! I do the very same thing, for the very same reason.

    I don't see the sense of needlessly pressurizing the brakes merely because the driver's door is opened, while the transmission is still in Park.
     
  14. macman408

    macman408 Electron Guidance Counselor

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    It's not clear to me which volatile RAM (or even what sort of a device) you're referring to here?

    The simple answer is that by definition, volatile memory is any memory that requires power to hold the stored data.

    If you're asking why things use volatile memory rather than nonvolatile memory (and thus retaining data after a power loss), it's because volatile memory is often simpler, cheaper, faster, more reliable, easier to integrate into a chip with other logic, etc. etc. etc. Everything is stacked against non-volatile memory, except for that whole "doesn't require power" thing. Thus, when an application doesn't absolutely require non-volatility, it's usually preferable to stick with volatile memory.
     
  15. ETP

    ETP 2021 Prime(Limit),Highlander HYB Plat,B52-D,G,F,H

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    I gave my 2007 to my daughter and before it had to be towed it started to have peculiar problems. Once the car was still on and she was able to lock it and walk away with no warning of any kind. If you notice you car is possessed try changing the battery. LOL
     
  16. GregP507

    GregP507 Senior Member

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    So many apologists for stagnant engineering.
     
  17. Former Member 68813

    Former Member 68813 Senior Member

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    if you want to make it overkill, use load tester like this.
    I use it in various cars, but haven't used it in prius yet.


    [​IMG]
     
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  18. Easy Rider 2

    Easy Rider 2 Senior Member

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    Interesting.
    Does that charger actually do 24 V ?
    And does it claim to adjust the voltages that it uses based on ambient temperature ?

    While +.6 volts might be the optimum for charging an AGM battery, the lower voltage still works but just takes longer.......and might leave it at 98% charged instead of 100%.......which is not significant to anything in normal use.

    And so many repetitions of "Don't confuse me with facts because my mind is already made up."
     
    #78 Easy Rider 2, Jan 31, 2015
    Last edited by a moderator: Jan 31, 2015
  19. Mendel Leisk

    Mendel Leisk Senior Member

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    I noticed (somewhere) a table of recommended charging voltages, for various ambient temps. Voltage values go up as ambient temp goes down. What this says to me, right or wrong, is that bringing a battery in the house, out of the cold, any charger will be more effective?

    image.jpg

    (Out of our son's Civic, yesterday)
     
    #79 Mendel Leisk, Jan 31, 2015
    Last edited: Jan 31, 2015
  20. jdcollins5

    jdcollins5 Senior Member

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    There is a 12V model and a 24V model with one manual. I purchased the 12V model 12248.

    Yes, it has a temperature sensor attached to the charger for temperature input.

    Go to the BatteryMINDer sight and check it out.

    Den49 has a thread about this and other BatteryMINDer units. Check out his thread.