Dead 12v, now hybrid battery isn't charging

Discussion in 'Prius v Care, Maintenance and Troubleshooting' started by risenicarus, May 14, 2019.

  1. risenicarus

    risenicarus New Member

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    Sorry for the long post, I want to make sure I can accurately state the issue.

    I had not driven my prius for a week, and I go yesterday to make sure it still starts up and it turns out the battery is dead. So we called AAA, the guy came out and jumped it for us. I did some research waiting for him to arrive and figured out it was likely a cause of the dome light being left on - turns out somehow the dome light had been turned on and left on.

    But now the battery is behaving oddly.

    After jumping it, I noticed the battery gauge on the dash was only missing two or three bars, fairly usual. But within a few minutes, it dropped down to only two or three bars left. The AAA guy suggested we take it to a nearby autoparts store, so that they could charge it. On the way, the battery got up to about half-full, and then immediately dropped back down to two.

    I parked the car at the autoparts store and it was at three. When I turned it on again a few minutes later so the autoparts people could check my battery, it had dropped down to two.

    I then explained that it didn't seem to be charging well during the drive, so they directed me to the nearest service place. I had to leave my car overnight.

    I get a call this morning after they'd checked it out, they said they needed to run diagnostics to figure out what was going on because "the motor wasn't running long enough to charge the hybrid battery" (his exact words).

    I told them to run diagnostics, but I wanted to ask here, as I figured actual prius owners might know more about this issue than a servicer who has never seen this issue before.

    Any help is appreciated!
     
  2. rjparker

    rjparker Senior Member

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    The hybrid 201v battery is what the gauge is showing. If your lucky a 10 or 15 minute drive might charge it up. Understand it will go up and down normally. The problem is if it goes down sitting at a traffic light.
     
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  3. risenicarus

    risenicarus New Member

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    According to the diagnostics, there was a blown fuse that needed replacing. Hopefully this fixes it.
     
  4. bisco

    bisco cookie crumbler

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    welcome!
    the fluctuating hybrid battery gauge usually means it is on it's way out. very possible in the az heat.

    a toyota dealer, or prius knowledgable repair shop will have tech stream diagnostic software, and can tell you the problem in a short time for a hundred bucks or so.

    you need a healthy, fully charged 12v to do any testing though. if it is original, you might as well replace it, unless you aren't going to keep the car if it needs a new hybrid battery.

    all the best!(y)
     
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  5. rdgrimes

    rdgrimes Senior Member

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    This is not unexpected behavior when the 12v battery is dead. The system is running overtime trying to charge a 12v battery that won't take a charge. Replace the 12v battery and everything should return to normal. If that's the original 12v battery then its WAY-WAY past needing replacement.

    Do yourself a huge favor and ignore anything that anyone says about it till the 12v batt is replaced. FWIW, the ICE isn't supposed to run till the traction batt is "full", it only runs till its gets to 3 bars. Sounds like the repair shop has no idea how the HV system works. Get the 12v batt replaced then get the car away from them.
     
  6. rjparker

    rjparker Senior Member

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    Let us know the end result...
     
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  7. risenicarus

    risenicarus New Member

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    Okay, so here's what the story is up to now:

    - I picked my car up from the repair shop yesterday
    - They explained that the fuse they replaced was the fuse that kept the batteries from drawing off of each other
    - Meaning the 12v was drawing off of the hybrid battery, which would explain why the battery seemed to not be charging
    - They charged my 12v and said I was good to go​
    - On the drive home, EV mode wasn't auto-engaging when it normally would (when I pulled into the driveway, when I was driving through the neighborhood, etc)
    - Could have been because the car was sitting in the sun when I went to pick it up
    - Could have been because the hybrid battery was too low to allow it to run (even though the indicator on the dash said it was only missing two or three bars)
    - ???
    I haven't driven it since I got it home yesterday, which took about 15 minutes. Should I be concerned about the EV mode, or is this normal behavior for it? The rest of the car seems fine, aside from the fact the clocks and MPGs reset (probably because the AAA guy pressed the reset button when he jumped the battery, or so he said).
     
  8. rdgrimes

    rdgrimes Senior Member

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    You're really not providing enough information for anyone to say much. But its clear that far too many people with no knowledge of the systems have had their hands on it. Get a NEW 12 batt as soon as possible, then see how it goes. Until you do that the system isn't going to behave normally.
     
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  9. risenicarus

    risenicarus New Member

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    What kind of information do you need? And what kind of battery should I be looking for? If I remember correctly, the AAA guy said it was a 615 or something similar
     
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  10. sam spade 2

    sam spade 2 Senior Member

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    THIS is a critical point.......that even Toyota shops often overlook.
     
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  11. bisco

    bisco cookie crumbler

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    wherever you go, or online, all you need is make, model, and year. they'll either have the right battery or they won't
     
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  12. bisco

    bisco cookie crumbler

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    ask them what fuse they replaced and post it here. has your battery gauge stopped fluctuating?
     
  13. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    Has the 12v ever been disconnected, charged and load tested? What were the results? What is the 12v battery voltage with nothing running or on?
     
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  14. rdgrimes

    rdgrimes Senior Member

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    At this point I'd say go to the dealer and tell them to replace the 12v battery. They'll find a way to charge you $300 before you're out the door, but at least you're not dealing with a shop that knows nothing about the car.
     
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  15. William Redoubt

    William Redoubt Senior Member

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    Depressing, but true. I have twice had to replace the 12 volt in my 2016. Both times the vehicle threw off a bunch of codes that went away once the 12 volt was replaced.
     
  16. rjparker

    rjparker Senior Member

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  17. Prodigyplace

    Prodigyplace Senior Member

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    That is not normal! What was killing the battery? My 2017 and my son’s 2015 v are still on their first batteries.
     
  18. William Redoubt

    William Redoubt Senior Member

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    The car spends most of its time in the southern California and Arizona deserts. Per Indio Toyota service, the heat kills the batteries as they are now under the hood, not protected by the interior placement, as older cars are.
     
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  19. The Electric Me

    The Electric Me Go Speed Go!

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    I'm assuming Original 12 volt battery.

    So this is a 7 year old battery that was drained to the point of needing a jump.

    I'd take this opportunity to simply replace it. Especially with the manifestation of symptoms in the wake of the battery being drained.
    IMO 7 years for a Prius 12 volt, is a good run.
    The worst case scenario here would be you are replacing a 12 volt, that has some degree of life left. But after 7 years and being drained? That wouldn't be much anyway.
    I wouldn't pass go, I'd just replace the battery.
     
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