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Advance notice of Auxillary battery dying ?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Tony2020, Aug 10, 2010.

  1. Tony2020

    Tony2020 New Member

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    I am a novice when it comes to car stuff.., so there may be easy answers to my questions.., but thought good to post this here.

    I drop over 35 miles in 102 F weather in Washington DC metro area and parked in the garage.., and as I pressed the park button, with the headlights and wiper blades still on, the engine warning light came on and a shrill noise was heard. Then the Prius conked out.
    We had luggage in the trunk and we could not open the hatch door. So we had to get the luggage from inside the vehicle.
    Then, i captured the strange flickering of the icons on the dashboard, with my video camera - and this is posted on youtube. (search for CIMG5374.MOV on utube. It is the second one. sorry i couldn't post it here, due to the 5 post limit. )

    Kept the garage door open in the night, due to the smell.
    Call the towing company next day, was able to jump start the car and took it to the dealership for testing.

    After doing their diagnostic testing, they informed me that they were not able to pinpoint that the aux. battery was bad since one test showed it holding the charge at 25%, but they suspect that as the likely culprit and would like to change it. Hesitatingly , i said yes.
    Later on this proved to be correct.
    I also have a picture of the aux. battery where you can see ( i believe two of the cells have conked out.. ? )
    Then i was wondering if anyone knows the answers to these qns, that i have posed to Toyota customer care folks:

    1. why cannot the diagnostics tell the Auxiliary battery is bad ?
    2. why cannot there be any kind of warning indicator that the auxiliary battery is going bad.., before this happens ?
    3. How to ensure that in future that the smell will not come in to the car ?

    appreciate any insights, from this group. thanks.
     

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  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. Do you know what DTC (diagnostic trouble codes) were logged by your car? I expect that at least one of the DTC registered low voltage on the 12V bus. I'm not sure why it was so hard for the tech to suspect the 12V battery, and why you would hesitate to approve its replacement.

    2. Good question. That would require more electronics to monitor the 12V battery condition. Since there isn't a warning, I suggest that owners consider replacing the 12V battery at four-year intervals if they live in a snowy area; otherwise at six-year intervals.

    3. Regarding your photo and the smell, did you remove the labels that are shown near the top of the battery? Normally those labels cover the translucent plastic cover over the six battery cells. I am wondering whether the battery had some accident which causes the labels to be dislodged; or whether you removed the labels in an effort to gain access to the battery cells.

    The battery has a rubber vent tube which is supposed to vent gases produced by the battery to the exterior. Was that tube moved out of place? If so that might explain why you noticed a smell.
     
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  3. Tony2020

    Tony2020 New Member

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    1. i have attached the code sheet - that the technician printed.
    ( the low bat is his writing.. not sure the code says that. ). But also the issue is once the aux. battery died - then i suspect the codes are not saved in memory. ( since i had to get a jump start the next day). So the car has no recollection of it dying the day before. correct ?

    2. thanks.., might do this in 4 years hence.., knowing mine died less than 5 yrs.

    3. we removed the label( which covered over the 6 circular holes) at the top - to see the six cells.., and by seeing it, i suspected 2 out of 6 were bad.

    I dont think so - on the vent question.., since all i had done to this car, since i bought were tire changes and oil changes. So that vent - if in the back of car - that would have been as-is since the day it was built.

    and finally, thanks for your reply....
     

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  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes, DTC C1241 "Low Battery Positive Voltage or Abnormally High Battery Positive Voltage" is produced by the skid control ECU and shows that the 12V bus voltage was at 8.5V or lower.

    DTC C2318 "Low Voltage Error" is produced by the transmission control ECU and also shows that the 12V bus voltage was at 9.3V or lower.

    So, a reasonable amount of evidence that the 12V battery was bad. It is true that if voltage on the 12V bus drops low enough, then the DTC will be lost on most ECUs (but not the skid control ECU and SRS ECU, which will keep the codes in memory even when power is removed.)

    Tell me about the abnormal appearance of the two battery cells:

    - What about them looked different compared to the other four?

    - Did you see white fuzzy mats between the lead plates, when looking into the cells?

    - Did you see any liquid electrolyte; or was the battery totally dry?
     
  5. Tony2020

    Tony2020 New Member

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    1. i didnt get to look too long at the battery.., but picture i attached was snapped with the camera phone.
    The two had greenish white deposits., as if that cell was bubbling and boiling over. All the others were clear.
    ( also - car died on a sunday afternoon - while i inspected the battery again on a monday evening at the dealership).
    2. not sure i understand this question about fuzzy mats between the lead plates - but i dont think saw any white fuzzy mats.
    3. It was dry.., or to put in better, dried out by the time lapse.
     
  6. richard schumacher

    richard schumacher shortbus driver

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  7. dogfriend

    dogfriend Human - Animal Hybrid

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    I was going to suggest that dropping MPG without another explanation (low tire pressure, new tires, different driving patterns) is often an early warning sign of impending 12V battery failure.
     
  8. richard schumacher

    richard schumacher shortbus driver

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  9. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Lets imagine you had a defective 12 volt battery and wanted a diagnostic to detect that. What would power the diagnostic?
     
  10. Patrick Wong

    Patrick Wong DIY Enthusiast

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    My home has a burglar alarm that is powered by 120VAC but has a 12V, 7Ah battery for backup in the event of an AC power failure.

    Every four hours, the alarm circuitry tests the 12V battery. My guess is that it places the battery under load and sees how quickly battery voltage drops. I would venture to say that similar circuitry would cost more than $1 in parts.

    A few days ago the alarm control panel started beeping, five beeps every minute. How irritating...

    I dug out the owner manual and figured out that the 12V battery (original was four years old) was the problem. So I ordered a new battery via Amazon.com, received it today and installed it this afternoon. I also figured out how to temporarily stop the beeping, but it would resume each time the battery was tested and found wanting (i.e., every four hours during the day, except the beeping went to sleep from 10 PM to 8 AM.)

    The alarm circuitry maintains 13.2VDC across the battery. I removed the old battery and measured its voltage after a few minutes. It was only 12.1V, so it was pretty obvious that it needed to be replaced. The new battery was 12.8+V out of the box.
     
  11. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Hmm in that scenario, you can take the 12v battery out of the circuit to test it, as you have another power source. (this is safe because you rarely crash your house, Toyota has to worry you will crash your car)

    Up to this point Toyota has been careful not to run the HV circuits unless the 12v diagnostics claim everything is OK. Running the 12v diagnostics on 201v is going to violate a lot of promises to First Responders at car crashes.

    I do not think this is insurmountable, but taking the 12v battery out of the loop in a car is not as straight forward as when using household 117v AC. The Prius may be the best car to do this in, however as there is less variability from the inverter than from an alternator.
     
  12. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes. My idea would be that after the Prius is READY and the DC/DC converter is functioning, then the 12V battery could be taken offline occasionally, to assess its condition. However this would be a fairly complex design and as previously mentioned, would likely cost substantially more than $1 in parts.

    The 12V battery could not be taken offline in a conventional vehicle, because the 12V battery is depended upon to smooth and filter the current produced by the alternator.
     
  13. StuL

    StuL New Member

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    I just had an electronic failure, wouldn't boot up, a bunch of abnormal lights and flashes. Kept trying to get it going, waited over 2 hours for tow. And then on a lark tried it one more time, got a parking pawl error message, somehow I reset the P and drove 2 hours home. Took to dealer and they noted "internal short in battery" and replaced it. ALso they reported the aux batt voltage low and suggests replacement (185 total). Today I note mileage was terrible, even coasting said I was getting 35 mpg. Consistent with aux battery failure (2009 prius with 25,000K)