Total Loss of 12V in 2010 Prius

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Peter P, Aug 11, 2019.

  1. Peter P

    Peter P New Member

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    Our 2010 Prius has developed an awkward intermittent problem. Twice now we've returned to the car after being away from it for a time (15 minutes, 2 hours) to find the dash completely black. No lights or indicators at all when we entered the car. The second time I verified that the horn and headlights didn't work. We had it towed the first time, and boosted then towed the second time.

    The second time I measured the voltage from the boost connection (in the fuse box) to ground - 0 volts.

    Of course, while at the shop, it never failed. There were no useful codes, and the 12V battery passed whatever tests they were able to do.

    They pulled off the dash to examine the wiring and found nothing amiss.

    I suspect an intermittent open connection inside the battery itself, but until it fails again, I can't check this. I'm unwilling to spend about $CDN 450.00 on a new 12V battery "just in case". In the meantime, we have an unreliable car and are burning through cash getting it towed and looked at.

    Has anybody any thoughts about this?
     
  2. dig4dirt

    dig4dirt MoonGlow

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    What is the age of the current battery?
     
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  3. Peter P

    Peter P New Member

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    Approximately 4 years. It’s the second 12V battery in the car.
     
  4. Peter P

    Peter P New Member

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    Just checked our records. Actually, the battery is much newer: It was replaced in February of 2018.
     
  5. dig4dirt

    dig4dirt MoonGlow

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    It may be deeper issue then just changing the battery.
    Can you get another battery test at another auto parts store?

    I had two issues in the past with my 2015 where I had to boost and I am still running same original batt. I suspect in my case it was either left in ready mode or door was ajar. (Happened a few years ago)

    I supposed u don't have a multimeter laying around to be able to test battery for a few days?

    I have read many say that multiple dead batt and jumps should be followed by serious thoughts of replacing...perhaps with a cheaper alternative?
    Where is Mendel when u need him?

    Battery dead in 15 min or so sounds like loose or dirty connections, bad battery or perhaps it is not charging during the previous drive?

    What irrelevant codes were shown?
    Any aftermarket items that are hooked up?
    Any corrosion on terminals?

    You still driving?
    How long between this time it happened since the last?
     
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. Carry a meter in the car so the next time this happens you can measure battery voltage at the time this is going on.
    2. Check the tightness of the battery cables, especially the negative cable where it bolts to the body ground.
    3. Find a less expensive 12V battery. One example:

    4. See if your local battery stores carry the Bosch AGM battery for Prius.
    Bosch 12v Battery | PriusChat
     
  7. Peter P

    Peter P New Member

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    I'm pretty confident in the battery test - it was done by the Toyota dealer, twice. We are carrying a multimeter in the car, waiting for the next event. I really want to check the battery voltage at the battery terminals when this happens.

    The irrelevant code was something to do with a key fob. I say irrelevant because when we got in the car when it was in the "no 12V" state, there were no indications of any kind on the dash, and even if you have no fob with you, you get some lamps and the horn and headlight work.

    No, no aftermarket items, and the battery connections look clean and are very tight. We are still driving, but being careful to park in places where a tow truck would have access if need be.

    It was just a few days between the two ocurrences - less than a week.
     
  8. Peter P

    Peter P New Member

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    We are carrying a meter. Checking the battery terminal voltage the next time this happens will tell the tale.

    Thanks for the suggestion about the negative cable - I checked and it is clean and tight. I'll check out the Bosch battery availability, but I'd really like to be sure before replacing the existing battery.
     
  9. bisco

    bisco cookie crumbler

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    welcome!

    get a jump pack
     
  10. Peter P

    Peter P New Member

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    Certainly an option, but I would really like to fix the problem, whatever it is.
     
  11. ASRDogman

    ASRDogman Senior Member

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    Many places offer a 2 year no charge replacement for the battery. And then pro-rated after that.
    You may just have a bad battery.
    Maybe you are not driving it enough to keep it at full charge?
    How LONG do you drive the car?
    You could get a 4amp battery charger and charge it overnight (12hours).

    Years ago I had an intermittent problem with the battery going dead, at anytime.
    I was finally able to get a load tester on it and banged the battery a few times and it would go dead.
    Somewhere there was a poor connection between cells or at one or both of the terminals.
    I still could not convince the people at walfart that it was bad.

    I finally sucked out the acid in one cell, and filled it with brake fluid. It took about 2 days, but it finally died
    and would not charge. They tried to charge it, and agreed it was dead, and finally replaced the battery!
     
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  12. Peter P

    Peter P New Member

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    Thanks for this. I was leaning towards the idea of an intermittent inside the battery as an explanation, myself. I just went out, turned on the headlights, and tried banging the battery with a rubber mallet, on all sides and top, but it didn't quit. Not a flicker in the headlights, taillights or dash indicators.

    It's not a charging problem: both times when the 12V died, after being towed to the dealer's, the battery tested fine, i.e. fully charged. The car was turned off during the tows.
     
  13. bisco

    bisco cookie crumbler

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    i wonder if a short in the combo meter could cause these symptoms
     
  14. ASRDogman

    ASRDogman Senior Member

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    Check ALL fuses. One could be broken internally.
    I don't remember if there is a fusable link on the battery or not.
    I wouldn't bank of the battery with a hammer! Rubber or not. I just used my hand.
    Something is look, or broken, obviously, just have to find it. Those are FUN!

    You didn't state how long you drive the car. If you don't drive it enough, it won't keep the battery charged.
    Thus the battery charger...

    ORRR, something is pulling a large draw on the battery when it's off.
    Because it seems to work find when it's running, right?
     
  15. Peter P

    Peter P New Member

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    Thanks for your continuing interest in this issue!

    ''...how long we drive the car..." - there's been no change in our driving habits over the last ten years or so. I think that the salient point is that, following one of these stone-cold-12V-dead episodes, by the time the car has been taken to the dealer's, all is well again. Battery tests by the dealer on arrival show no anomalies. Clearly no battery charging took place while the car was turned off and sitting on the bed of the tow-truck.

    It returns to normal, in time, with no charging going on.
     
  16. CR94

    CR94 Senior Member

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    Yes, it should. Result?
     
  17. Peter P

    Peter P New Member

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    Nothing yet. The dang thing is working like a charm so far. Maybe the various pokings and proddings by the techs fixed something. I'd be much happier if it failed and failed solidly.
     
  18. Mendel Leisk

    Mendel Leisk Sidewalk Supervisor

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    Canadian tire has a battery for the Prius, around $200.

    They probably do an electronic load test. There are prosumer level versions of those testers. I use a Solar BA5, and it looks like the current best entry level one is BA9. That said, the battery is fairly new, the dealership gives it a pass, sounds like connections or fuses.

    Simple thing to do when you have an event: check the voltage (with a multimeter) at the battery posts, and then at the jump point. If you're getting 12+ volts at the posts, and nothing at the jump point...

    Watching Netflix, snoozing. :oops:
     
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  19. Peter P

    Peter P New Member

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    Thanks, that's exactly what we're waiting for. Kicking ourselves that on the second event we measured at the jump point but not the battery.
     
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  20. dig4dirt

    dig4dirt MoonGlow

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    Since I too had the dead batt a few times and both my batts are original (5+ years now),

    I have one of these sitting in my amazon cart tempting me to pull the trigger.

    I figure that due to it not being a HUGE complication if one of us gets stranded,
    I do not need it right now, but probably soon.
    ( the other one of us can always come to help the other if needed with cables)

    But if necessary, this little CHEAP jump pack has great reviews
    jump pack
    and only $30
    Not sure if you have prime up there way past MAINE!

    bisco mentioned first, but may be worth it instead of another tow.
     
    #20 dig4dirt, Aug 13, 2019 at 8:20 PM
    Last edited: Aug 13, 2019 at 8:29 PM
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