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2010 - Sudden 12V Battery Failure

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by jdcollins5, Jan 25, 2015.

  1. Den49

    Den49 Member

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    I had a similar out-of-the-blue failure of my 12V battery about this time last year in a snow storm. You deserve a special DIY commendation for diagnosing and repairing the problem in a prompt, efficient and exemplary manner.

    BTW, I think it has been reported that the Toyota 12V replacement battery you bought is much more reliable and long-lived than the OEM new car battery, as indicated by the seven year warranty. (y)
     
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  2. jdcollins5

    jdcollins5 Senior Member

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    Patrick was the first that I have seen on here decipher the battery date codes. I was just following his examples. Maybe this is the standard date code format for Japan ?

    Many of the date codes that we see with European and Asian equipment correspondence follows similar formats and is different than US or Canada.
     
  3. The Electric Me

    The Electric Me Go Speed Go!

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    I actually think it's a combination of what The Prius aux battery IS size and strength...and also how it is used by The Prius.

    This combination of realities seems to be able to create the illusion of "sudden failure".

    No direct alternator, coupled with the Battery not really "cranking" the engine, doesn't provide people with the usual and expected warning signs that a battery is weakening or failing.

    There is no ICE vehicle that didn't give me ample warning that I might want to start thinking about a new battery, without testing it, it was just when the cranking of the engine became labored and the headlights would dim under load.

    Reading years of posts here? It does seem that The Prius aux battery can fail in what appears to be a sudden manner, and with any number of associated "Gremlin" like symptoms.

    If I have the financial means, I surely plan to replace mine within 5 years. I consider that good life for a battery it's size and don't want to risk being stranded.
     
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  4. Former Member 68813

    Former Member 68813 Senior Member

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    the made in japan batteries in RAV4 do exactly the same. they are good one day and dead like a doorknob next. internal short. some can even belch sulfuric acid or hydrogen sulfide as they die. my wife got once "stranded" in a local shopping mall. I need to be proactive as prius is her commuter car now.
     
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  5. Jonny Zero

    Jonny Zero Giggidy

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    All my made in Japan Toyotas (except for the Prius) came with Panasonics which lasted and lasted.
     
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Following the first method in the second video I posted above, I checked for phantom power usage this morning. Looks to be very low, around 16 milliamperes, with little spikes to around 40. Maybe due to the flashing security light? Acceptable is said to be on 20-50 range, so good I guess. :)

    image.jpg

    (Finally sorted out posting images on an iPhone, need to click on text ABOVE button, button inactive. )

    Gotta get some alligator clips for my new meter, lol.
     
    #26 Mendel Leisk, Jan 27, 2015
    Last edited by a moderator: Jan 27, 2015
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  7. jdcollins5

    jdcollins5 Senior Member

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    I learned another lesson with replacement batteries. It pays to charge a new battery to full charge before installing.

    Even though the new battery tested at 12.93 volts before installing and then charging while driving 25 miles to work, when I checked the battery after sitting in the parking lot at work all day it only read 12.4V. On the drive home I noticed that the charging circuit was at 13.5v rather than the normal 14.5V and had dropped to about 13.2V by the time I got home.

    When I turned the car off it dropped to 12.2V. I put the car in IGN-ON mode and it dropped to 12.0V. I turned on the headlights and it dropped to 11.6V ! My first thought was that I must have a parasitic drain, especially after reading Mendel's post !

    I hooked up a charger to the battery and charged it at 13.5V for 4-5 hours. When I checked it this morning it was at 12.7V. While driving to work the charging circuit was at 14.5V all the way to work. Charging was also normal on the drive home.

    When I got home and checked the battery after sitting a short period it was at 12.9V. So it looks like the battery is slowly getting to a full charge. Time will tell.

    I am going to have to do a battery parasitic drain test this weekend just to ease my mind :)
     
  8. Mendel Leisk

    Mendel Leisk Senior Member

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    These are the steps I followed:

    1. Hooked up a charger at the underhood jump start point. (CTEK 3300)
    2. Disconnected negative battery cable. (looped the cable end through cargo hold down net D-ring, for safekeeping)
    3. Hooked up alligator clips with longish leads, one to negative post, and one to end of negative cable.
    4. Ensuring leads stayed separated, ran them out through hatch and taped to floor. Then closed the hatch. (Leads are barely pinched, no trauma.)
    5. Set my multimeter to amperage, moved red lead over to amp plug in, hooked up multimeter leads to those run out of hatch. (Mine is multiranging, if not, you want to set to highest scale at first, for safety.)
    6. Disconnect the charger. Don't open any doors, keep your fob out of vicinity, wait a while and watch multimeter readings. Mine were initially high, over 1 amp, especially before disconnecting the charger. Then the settled down a bit, then went way down. Seems to take a while for everything to shut down, go to sleep.
    7. Reconnect charger.
    8. Disconnect multimeter.
    9. Disconnect alligator clamp leads from battery and negative cable, and reconnect battery.
    10. Disconnected charger.

    FWIW, with a battery that's a bit over 4 years since install, charged a week or two back: after a drive to burn off surface charge, the battery showed voltage (at rest, on multimeter) of about 12.7. Then a few days later 12.6. This morning it's around 12.39. Doesn't appear to be parasitic drain, I'm thinking it's just deteriorating, not able to hold a higher charge. It does see to stabilize around 12.35~12.40. May be a new battery in the cards for me soon, too.

    And yeah, even if you install it at point of sale, it's good to hook it up, say as soon as you get home, let it fully charge with a smart charger.
     
    #28 Mendel Leisk, Jan 27, 2015
    Last edited: Jan 27, 2015
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  9. jdcollins5

    jdcollins5 Senior Member

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    What is the correct fully charged voltage for our AGM batteries? I checked the Owner's Manual and it says 12.8-12.9V.

    I have seen a table posted on here where I thought it showed a higher fully charged voltage above 13.0V but cannot seem to find it. Can someone re-post this table ?
     
  10. bisco

    bisco cookie crumbler

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    check dorunron's posts, he's the battery king.
     
  11. Easy Rider 2

    Easy Rider 2 Senior Member

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    Unless you have put in a different brand of battery, the Owner's Manual is correct.

    Some brands of batteries can run a tiny bit higher but that last tenth really isn't important.........and it is more likely that your meter is off than the battery actually holding a charge higher than 12.9.
     
  12. jdcollins5

    jdcollins5 Senior Member

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    From the battery tables for AGM that I have checked so far the 12.8V at 80F is listed as 100% SoC. I am not concerned with 0.1V either way I just wanted to be sure starting with the new OEM battery that I knew what 100% SoC was. The Owner's Manual gives at 68F and this closely matches the other tables:

    12.6 ⎯ 12.8 V Fully charged
    12.2 ⎯ 12.4 V Half charged
    11.5 ⎯ 11.9 V Discharged
    (Voltage is checked 20 minutes after the hybrid system and all lights are turned off.)

    As for my meter I have confidence that mine is close enough since it agrees with the SGII battery volt reading.
     
  13. Easy Rider 2

    Easy Rider 2 Senior Member

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    All of that sounds right to me but................
    Equating SOC with resting voltage is a tricky thing.
    The battery is not REALLY dead until it reads below 10.
    Those figures are just a rough indication.
     
  14. GregP507

    GregP507 Senior Member

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    Rough indication is right. That scale might be reasonably accurate for a new battery, but nothing is new forever.
     
  15. jdcollins5

    jdcollins5 Senior Member

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    From Repair Manual:

    3. INSPECT BATTERY VOLTAGE
    (a) Measure the auxiliary battery voltage with the power switch off.
    Standard Voltage:
    11 to 14 V
    If the voltage is below 11 V, recharge or replace the auxiliary battery.

    The problem is that with the Prius you are subject to get a lot of random alarms and DTC's when the battery voltage gets low. At what voltage level does this start ? Somewhere below 11V?
     
  16. Mendel Leisk

    Mendel Leisk Senior Member

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    We've got a couple of cars sitting in garage right now. A civic with a 16 month old conventional battery, and our prius with the OEM AGM battery, put in by the dealership over 4 years ago, as of last November. Ambient temp is 7C. Both cars have been sitting since last Sunday, when both got a good drive:

    civic: 12.46 (volts)
    prius: 12.42

    (readings with a Milwaukee TRMS meter)
     
  17. jdcollins5

    jdcollins5 Senior Member

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    According to the Prius Owner's Manual the Prius battery is at 50% SoC. The 12.5V is what I was used to seeing on my original battery.
     
  18. Former Member 68813

    Former Member 68813 Senior Member

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    this is not normal. however, I have the same thing with my rav4, if it seats several days the voltage goes as low as 12.4V. the battery is 2 year old. at the beginning it would go to 12.5V, now it's a bit worse. i blame the emission parts that are alive and active several hours after you shut down the engine. you can hear electric pumps running during the night. I never had that issue in corolla or yaris where it would be near 12.7V.
    I may need to monitor prius' battery closer as it over 4 years old.
     
  19. Former Member 68813

    Former Member 68813 Senior Member

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    weird, sounds like it's partially sulfated? maybe the stealership took a discharged battery and charged it up just before giving it to you?
     
  20. jdcollins5

    jdcollins5 Senior Member

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    The Parts Manager did not have time to do this. I was the first customer when they opened that morning and after looking up part numbers he walked straight back to the parts area and came back with the battery.

    After charging the battery it appears to be holding the charge well now. I will continue to check it each day to make sure and try to get a good baseline.

    I want to attribute this to having close to a year of shelf life before being installed ?