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12v Battery Replacement. DO I need to go OEM & would bad battery cause the System Check to crash?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by docproteus, Nov 1, 2021.

  1. docproteus

    docproteus Junior Member

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    Two questions.

    My daughter was driving our 07 Prius, 200,000 miles and no issues and she said that the speedometer etc all went out. I got in the car when she got home and didn't see an issue and put it into the diagnostic screen. Battery was at 12.3 with one click of the button and 11.9 with two. Starting up it jumped to 14.3. Assuming this means the batt is going bad and that is the reason that the info went out? Also, when I went into the diagnostic screen it would stay on for about 45 minutes and then kick out to the toyota logo. Anyone seen that before?

    Assuming I have to replace it is there a need to go oem because I can't source one locally?

    Thanks
     
  2. burrito

    burrito Active Member

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    How old is the existing 12V battery? Have you had it load tested at an auto parts store (it should be free)?
     
  3. koco

    koco Member

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    The only way for the battery to jump to 14.3v is that the car's charging system kicked in, otherwise it would be around 12.5 or so for a seasoned battery.

    And yeah, get the battery load tested because voltage alone will not always tell the tale.

    You probably have the instrument cluster issue that causes the speedometer to go dark from time to time exacerbated by a low auxiliary battery.
     
  4. docproteus

    docproteus Junior Member

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    Hadn't thought of that. So it's the same load test as a standard 12v car battery (apologie sif that is a stupid question) or do I need to make sure they know how to load test a 12v that only does what our batts do?

    Bought the car used about 5 years ago so it's at least that old.

    If I do replace and can't source an OEM is there a downside with going with another? I've read a few places that if it's not the OEM it wont last very long.
     
  5. Another

    Another Senior Member

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    Five years for a 12v is pushing the envelope.
     
  6. docproteus

    docproteus Junior Member

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    Kind of what I thought so probbaly just going to replace rather than pulling it and having it checked. I'm trying to source a TrueStart locally but if I can't are there issues with aftermarket batts? Can't seem to lck down if there are or arent.
     
  7. sam spade 2

    sam spade 2 Senior Member

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    That's because the real answer will vary with the brand name and the vehicle involved.

    No good reason to think that a "name brand" battery bought from a local outlet will not be just as good as OEM.
    Getting one that is "exact fit" is a good idea.
    Others may not fit in the space right or might have different kinds of posts.

    Be sure that your new one is fully charged before (or immediately after) installation.

    Note: While it is time for a new battery anyway, those numbers are not all THAT bad......and might not be the cause of the problem.
     
  8. Aegean

    Aegean Active Member

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  9. burrito

    burrito Active Member

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    Oh, there's no need to remove the battery from the vehicle just to get it tested. They can clamp the tester onto the battery while it's still installed in the car. The device needs to know what kind of battery it is (should be AGM) and the capacity. It takes less than a minute.

    For some reason, when I had mine tested recently, the lady insisted that she had to attach the tester to the jump point under the hood. I politely insisted that I had already exposed the battery in the trunk. TBH, either way should be fine. The key to remember is to make sure the car is powered off during the test. If you end up buying a battery from them, they'll typically install it for free, on the spot (which is why they're happy to test for free).

    A new 12V battery might not fix your problem, but a bad power supply can cause quite strange behaviors.
     
  10. koco

    koco Member

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    Your instrument cluster probably needs a new capacitor that cost like $2...installing it takes a little while.