Considering 2010 Prius, 12v question

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by P Nyberg, Aug 26, 2021.

  1. P Nyberg

    P Nyberg New Member

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    I am considering purchasing a 2010 Prius 3. I am aware that this considered not the best year for the Prius, but the price is right, low mileage, etc…
    I currently have the car for a few days to see if it’s a good fit for me.

    I ran the internal diagnostics, and the 12v battery registered 11.4 from a cold start. When driving it goes up to 12.5.
    It seems to me this indicates that the battery needs to be replaced, but I am new to having a Prius.

    My question: would you recommend the purchase and replace that battery or could it be an indication of bigger problems down the road?
     
  2. rjparker

    rjparker Senior Member

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    The 12v battery is probably bad at those loaded and unloaded voltages. I would have it tested free at most auto supplies and then replaced if it fails. You could try a maintenance charger like a Battery Tender Jr ($28) over a several day period. The 12v agm battery might be $225-$300 depending where you buy it. A Toyota 12v would be at the high end but could last 7-8 years and is a good value over the long run.

    The 12v battery will likely be the least of your problems and the cheapest to rectify. The car's mileage would tell the story better. If it is much over 100k miles, I would run. You may have brake booster, head gasket, inverter and or high oil consumption to deal with during your ownership. Each is well over $2k although the inverter may still have a special extended warranty under some failure modes. The egr system is a problem as well with clogging of the egr cooler and intake manifold a $800 job at a dealer.

    Notice I did not even mention the thing most used Prius buyers worry about, eg the high voltage battery. It often makes 175k-200k miles and is also in the low to mid two thousands.

    The car might be worth a gamble at 40k-50k miles but only if the price left room for one or two of the bigger repairs. This Prius is one of the most complex vehicles ever made and shows it when bigger repairs are required. If reliability is important, consider a Camry (except 07-09), Corolla, Accord or Civic in your price range.
     
    #2 rjparker, Aug 26, 2021
    Last edited: Aug 26, 2021
  3. sam spade 2

    sam spade 2 Senior Member

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    Neither of those numbers are good.
    But the onboard diagnostic for the 12 V battery doesn't seem to be worth much either.
    You should insist on getting the battery replaced and the charging voltage tested BEFORE buying.
    That 12.5 number could mean that the charging system is bad.
     
  4. tankyuong

    tankyuong Senior Member

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    $$$ down the road
     
  5. Grit

    Grit Senior Member

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    saving gas cost a lot of money.
     
  6. P Nyberg

    P Nyberg New Member

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    Thanks for the advice - I can’t believe I didn’t think of going to autozone to have them test the battery. I’ll definitely do that tomorrow.
    The vehicle only has 40,000 miles on it, which is the main reason I’m even considering the purchase - the maintenance records are fairly robust, and it just seems it was owned by someone who didn’t drive much. I’m a bit doubtful, but I drive only about 4,000 miles a year myself, so it can happen.
     
  7. rjparker

    rjparker Senior Member

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    The 12v battery is under the mats in the right rear.

    If you buy the car change the oil every six months regardless of the mileage.

    F2BE15A5-BC12-4A5A-9284-8377039DCBD6.jpeg
     
    #7 rjparker, Aug 26, 2021
    Last edited: Aug 26, 2021
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