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What happens when 12v battery dies?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by bauerhillboy, Jan 8, 2014.

  1. Mendel Leisk

    Mendel Leisk Senior Member

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    Thing is, it's very easy for the customer to toast their battery. Used to be leaving the headlights on was needed. Now with diminutive 12 volts in hybrids, even a door courtesy light or cabin ceiling light will do it, in just a few hours. Dealerships would bleed if they freely replaced battery just based on time.

    If you can check the battery directly, with a digital multimeter, you'll get an idea of it's health. If it's showing 12.6 volts or better it's a 100% battery. 12.5, it's suspicious. 12.4, it's seen better days. And so on.

    Consider investing in a lowish amperage (3~4) intelligent charger. Hook it up and let it run overnight, it might restore the battery. After the session, drive it for a few days, then recheck with multimeter. (checking immediately after charging will show falsely high readings)
     
  2. drroone

    drroone Junior Member

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    anyone else have this 12v battery. I think my battery is on it's way out as well. Site looks a little off, but seems like a great battery
     
  3. JimN

    JimN Let the games begin!

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    Just my opinion: When scheduling the appointment and speaking with the service writer clearly state that if the replacement battery isn't covered under warranty then you don't want the work done. The replacement battery will have the (pretty crappy) 12 month unlimited mileage warranty just like Toyota's other parts.

    I did not have a good experience with Toyota's battery when I had to replace the 12v in my 2006. A battery from a dealer was not an option for the 2010.

    Elearnaid promptly mailed a fully charged battery to me so if a few days doesn't make a difference go this route.
     
  4. drroone

    drroone Junior Member

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    i the elearnaid battery the same as the battery that is listed on amazon $147.xx when you search "optima prius battery"
    I know pretty lame, im such a noob i can't even post links yet on priuschat.
     
  5. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    DS46B24R is the right battery
     
    drroone likes this.
  6. drroone

    drroone Junior Member

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    thank you sir!
     
  7. Gary in NY

    Gary in NY Member

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    The way this played out is all I got to talk to was the service writer, so all the details of what I described here probably never got to the tech who actually worked on the car. It worked out kind of as I feared: by the end of my hour long drive to the dealer, my 12V battery had fully recharged. The answer I got back from the service writer was "we checked your battery, sir, it tests out fine, there are no problems with it". So I never even got to the point of discussing whether it was covered under warranty or not. It seemed they weren't going to replace it under warranty if they wouldn't even agree it was bad, and I wasn't going to ask them to change it anyway (if I'm going to pay for a battery, I may as well pay for an Optima). Maybe they figured I was just trying to get a free battery out of them, or didn't check very thoroughly. I don't know what kind of tests they performed to decide the battery is OK. I suspect the battery is probably actually mostly OK, it's not "worn out" and should have a lot of life left in it. I think I have 5 cells (there's 6 cells of 2 volts each) that are perfectly fine, and a 6th cell that may accept a charge and deliver current OK too, but it also has an internal short that discharges this one cell over time, thus the battery drops to 10V but no further. Once it's charged, it probably tests OK until the internal short drains it. I didn't press the issue further, but maybe I should have asked to speak to the tech to make sure they understood my problem. Perhaps if I left the car there for a few days, or even took my battery and left it sitting on a bench for a few days, they would be able to confirm the problem. I have just a very short time left on my warranty if I want to ask them to do this.

    This matches my experience: if I take a long drive, the battery charges back up, and acts fine for a few days. If I leave the car parked a few days, it ends up back at just over 10V, and short drives don't help much to restore it.

    I know perfectly well that soon this battery is going to be back at 10V.
     
  8. JimN

    JimN Let the games begin!

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    I have had no luck getting any shop to properly test a battery & determine if it was "good'. What's their idea of good, 12v? Trying to buy one at a retail store was a hassle and it wouldn't charge up to my liking.

    In the time it took you to drive to the dealer you could have installed the battery yourself.