11 year old 12v battery still going strong, but should I replace?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Jay Hansen, Jul 9, 2020.

  1. Jay Hansen

    Jay Hansen New Member

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    Hello, I have a 2008 Prius with a battery that was installed in 2009. It is an OEM battery. I have no issues with it. Voltage after sitting overnight is 12.7 volts via multimeter at the battery terminal.

    With one press of power button in signal check mode on MFD, the reading is 12.4 volts. With two presses of power button, it reads 12.1 volts. With two presses of power button, headlights on, rear defroster on, and heater core on high, it reads 10.8 volts. From elearnaid and priusdiy, it appears my battery is fine. However, I am concerned it will fail suddenly and I will be stranded.

    Should I replace it? Or just keep going until it is weaker?

    Thanks for your input.
     
    #1 Jay Hansen, Jul 9, 2020
    Last edited: Jul 9, 2020
  2. SFO

    SFO Senior Member

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    Welcome to PriusChat!!

    How many hours per week are you driving the vehicle now?

    If you are concerned about being stranded, then replacing the 12v could be a prudent move.

    Given the incoming heat wave, have you had a chance to clean the HV battery fan?

    Seeing you name reminded me of another Jay Hansen (RIP) : BRAIN FOOD TABLE OF CONTENTS
     
  3. Jay Hansen

    Jay Hansen New Member

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    We use it for longer trips, so it varies. We just got back from a 1,000 mile trip. Many weeks, we don't use it at all. It sits in the garage. No I have not cleaned the HV battery fan. Is that something I should do when I replace the 12v battery since it is close by?
     
  4. JerryScript

    JerryScript Junior Member

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    If it ain't broke, why spend $200-$300 to fix it?!?
     
  5. fotomoto

    fotomoto Senior Member

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    So let's sum up the things you know:

    You know the battery is old.
    You know the battery is getting weaker.
    You know you fear being stranded.

    Get a new battery.
     
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Just for curiousity get it tested with an electronic load tester. Automotive retail stores selling batteries mostly have these now, and will likely test it for free. If the CCA has dropped below spec (something like 315?) I'd say it's time to replace. These testers will usually give a verdict as well. Google "Solar BA9" for one example of a DIY level tester.

    All that said, 11 years is a good run, lol. As previous responders have said, you've really beat the odds, but it won't go forever. But yeah would be interesting to see test results.
     
  7. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    It's overdue and you're still using the car for long trips, and you're specifically concerned about a breakdown. You pass the test, just replace it.
     
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  8. bisco

    bisco cookie crumbler

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    get a jump pack instead, and see how many years you can get out of it!(y)
     
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  9. Jay Hansen

    Jay Hansen New Member

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    I cleaned it per your recommendation. it had a little bit of dust, but not bad.
     
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  10. Jay Hansen

    Jay Hansen New Member

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    Interesting idea. I can get a NAPA AGM battery for $142 plus tax after rebate. I am leaning toward that, but am researching jump packs at the moment. The nice thing about the jump pack is I can use it on my SUV as well if the battery failed.
     
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  11. sam spade 2

    sam spade 2 Senior Member

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    Because lead acid type batteries don't last forever.
    Better to do it when it is convenient instead of having it fail in an unhandy or unsafe place.
    An 11 year old battery is on borrowed time.
     
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  12. edthefox5

    edthefox5 Senior Member

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    10.8 is dead jim.

    You should be seeing a red triangle flash for a second on the dash every time you start the car.
    That's the only warning your going to get the battery is ready to leave you.

    Also stop testing the battery's voltage on the battery itself. Its alot of work and not safe. Use the front jump point.

    It only matters what the voltage is there.
     
  13. Jay Hansen

    Jay Hansen New Member

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    This is incorrect. All of it. There is nothing wrong with checking voltage at the 12v terminals on the battery with the car powered off. Having said that, my load readings came from the MFD, not the battery terminal. 10.8 volts under the load I described is not dead. With no load, I am getting 12.7 volts. And no, I do not see the warning light you describe because the 12v battery is not bad...just really old.
     
  14. ChapmanF

    ChapmanF Senior Member

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    Recycling this post ...

    ... buying a new 12 volt battery because it's 'of a certain age' is like buying a kind of insurance policy that protects you very narrowly against one risk (getting stranded because of the battery's age).

    Buying the little jump pack, even if we make it the same price for sake of argument, is like buying a broader insurance policy that protects you against getting stranded because of leaving a light on, unexpected electrical drain, delayed return to airport parking, six other things you haven't thought of, or the battery's age. And you can use it to bail out friends or neighbors ...

    When I saw "10.8" in your original post, I first thought "hmm, might not be long now", but then when I read the test conditions (headlights and defroster and heater on high), I thought "well, I might be saying '10.8' too, if not 'uncle'."

    Anyway, the nice thing about having the jump pack is whenever the day comes (or any other kind of a day where it's handy to have a jump pack), you won't be inconvenienced much. If the battery really does say uncle, you say ok, I'm jumping the car and shopping for a battery.
     
  15. The Electric Me

    The Electric Me Go Speed Go!

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    Hey I would replace it.
    I would of replaced it years ago.
    BUT...
    I'm going to read in between the lines here, and say, if you've been pushing it for 11 years? Then you obviously are enjoying the game. At this point I say carry a portable jump start unit, so you don't get stranded, and just keep going. Then you can come back and say....I got 12-13 years out of my 12 volt battery...yippee ki yay!
    Waiting over a decade THEN asking if you should replace the battery?

    Once Dr. Frankenstein had the reassembled corpse on the table, and the lightening storm was approaching it was a little late to ask if this was a good idea. And I don't think he wanted to back out at that point.

    So...11 years?
    There is no good reason you should of waited this long. Even if the battery has been amazingly durable. You've already passed the bar, of should you replace it.
    I think you are well within the realm of....let's see how far I can get with this monster that won't die.
     
    #15 The Electric Me, Jul 9, 2020
    Last edited: Jul 9, 2020
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  16. Jay Hansen

    Jay Hansen New Member

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    Who said I waited this long? I just bought the car in April. I am going to replace it. Not into the Kramer game of seeing how far I can push the needle.

    So I took it down to Autozone and OReilly. Both load testers said it was bad. The OEM spec is 310 CCA, so it must be returning something less than that on the load calc, although neither of their testers gave me the actual reading. I am going to just buy a new battery. Still, the jump pack idea is intriguing.
     
    #16 Jay Hansen, Jul 9, 2020
    Last edited by a moderator: Jul 10, 2020
  17. Jay Hansen

    Jay Hansen New Member

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    Any suggestions on a jump pack by the way?
     
  18. The Electric Me

    The Electric Me Go Speed Go!

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    Sorry, but when your thread title is 11 year old battery still going strong but should I replace?
    I was kind of assuming a longer ownership experience than 3-4 months.

    Doesn't really change anything.
    If it's an 11 year old battery, I'd replace it....which was what you were asking.

    And anything counter to replacing an 11 year old battery WOULD be playing the Kramer game.

    So if you don't want to "push it" I suggest you don't pass go, and just get a replacement battery.
     
  19. fotomoto

    fotomoto Senior Member

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    Have you check the date code on the battery or are you going by what the original owner said?
     
  20. sam spade 2

    sam spade 2 Senior Member

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    Just stay away from ones that fit in your pocket, claim some outrageous capacity and have leads that are thinner than a lamp cord.
    Despite the marketing claims, they will only work reliably IF the battery is just barely too weak to boot up the car.
    If the battery is really DEAD, it will be mostly useless.......and if it is shorted, those leads might GLOW.
     
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