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Regen battery charging working extra well, MPG down...

Discussion in 'Gen 2 Prius Main Forum' started by Justdidit, Dec 19, 2012.

  1. Justdidit

    Justdidit LVNPZEV

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    I ran the on-board 'Self-diagnostic-mode' last night bcuz I didn't have time to take it somewhere to be tested.

    01. Powered Car into AC mode - Push Start button w/o brake pedal
    02. While holding down 'Display' button, I switched on/off the Headlights 3 times
    03. Car goes into Self Diagnostic mode
    04. On the first screen press 'Menu'
    05. Next screen press 'Display Check'
    06. Next screen press 'Vehicle Signal Check'

    Car displays:
    Battery at 12.0V
    IG: OFF

    07. Push Start button w/o brake pedal again to access IGN 'ON'-

    Car displays:
    Battery at 11.3V
    IG: ON

    08. Push Start button w brake pedal again to Start car-

    Car displays:
    Battery at 14.3-14.1V
    IG: ON

    Turned off car and Repeated steps 01-08

    Car displays:
    Battery at 12.1V
    IG: OFF

    Car displays:
    Battery at 11.3V
    IG: ON

    Car displays:
    Battery at 14.3-14.1V
    IG: ON

    Does qualify as bad or going bad??

    This would work during the day at work. (y)

    Switched back to stock intake box last night w/ no positive effect - 2day on the way to work MPG still low.

    Normally I would agree with the route being an issue as well but over a month ago when I would take the same route up the I-15N to Temecula for the weekend, I was getting at least 5mpg better than current.

    I appreciate EVERYONE's input. As of now the only thing I can see is that the 12V drops below 12V during IG ON mode. From what I've read...thats not good.
     
  2. dorunron

    dorunron Senior Member

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    IMO, based on information that I have gleaned from Prius Chat and elsewhere, your 12 volt battery is definitely weak. When you have a normal fully charged battery the values should be higher on the first two parts of the test. The last part of the test simply shows if the charging system is working properly.

    Your numbers were 12.0, 11.3, 14.3 to 14.1

    You should have a minimum of 12.4 for the first part of the test (Accessory Mode)
    You should have a minimum of 12.1 volts for the second part of the test (Ignition On)
    You should have a minimum of 13.6 and a maximum of 14.4 for the last part of the test (Ready Mode)

    The test you ran plainly reveals that the battery is weak/failing. I would suggest you obtain a new battery, and fully charge the new battery before you install it in the car. Once you have done that, your mileage should improve.

    Good luck to you and I hope this information helps you.

    Ron
     
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  3. Justdidit

    Justdidit LVNPZEV

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    Sounds reasonable, so know, what 12v to choose??

    $99 Kinetik HC600
    Part Number: KHC600
    850 Amp / 600 Cold
    (free shipping)

    or

    $169 Optima Battery DS46B24R
    Part Number: 8171-767
    575 Amp / 450 Cold
    (free shipping)

    Any other suggestions?? Thanks again!
     
  4. dorunron

    dorunron Senior Member

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    Most folks here on PC recommend the Optima Battery. That would be the better choice of the two you referred to. It is a true drop in type battery. (Same post configuration, same size as the OEM battery.) - I will not make a personal recommendation concerning the Optima at this time due to reports of recent Optima's living a short life that are being manufactured at the plant in Mexico. Optima recently changed production facility's IIRC.

    NOTE: If your car does NOT have SKS (Smart Key System), you will need to change the battery tray in your Prius, otherwise the Optima will not be held down properly with the battery hold down system in the car.

    Here is the info on the battery tray if you need it.

    2008 TOYOTA PRIUS Parts - Champion ToyotaWorld

    Item #8 is the battery tray, there are two different trays made for your car. One for SKS, one for NON SKS.

    Good luck to you and I hope this info helps you.

    Ron
     
  5. Justdidit

    Justdidit LVNPZEV

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    Smart key in hand so I should be good. Thanks again!
     
  6. dorunron

    dorunron Senior Member

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    If you do change the battery, take the time to fully charge the battery BEFORE you install it. Use a good "smart charger" and charge it until the charger says the battery is fully charged. Any battery that you buy new has usually set on a shelf for a period of time. A typical 12 volt battery will lose charge when sitting idle, and may also sulfate if left unattended for a long period of time. It is also a good idea to check the voltage of the battery before you install it. Most folks recommend the following steps.

    1. Fully charge the battery.
    2. Let the battery rest for a minimum of 8 to 12 hours.
    3. Remove any surface charge by applying a load to it for just a couple of minutes. (headlight on, or something similar)
    4. Measure the voltage with a digital volt meter.

    The voltage should read 12.6 or higher with a fully charged battery. Refer to the chart below for a good idea of SOC based on voltage measurements.

    Good luck to you and I hope this information helps you.

    Ron
     

    Attached Files:

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  7. bigblockcutlass

    bigblockcutlass Junior Member

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    traction battery is on it way down.
     
  8. Justdidit

    Justdidit LVNPZEV

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    What do you mean and what makes you think this?
     
  9. edthefox5

    edthefox5 Senior Member

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    Yup its done. The 11.3 is very low. If you were 2/10's more low on the 11.3 your would see a red exclamation point on the dash on start up. Its only there for a second like all the check lamps. It may be throwing it now you just never noticed.

    How many times have you had to jump it?
     
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  10. Justdidit

    Justdidit LVNPZEV

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    Never...

    Can someone clarify the batteries? I thought we were referring to the 12v battery. Whats the traction battery? Is the the larger battery pack behind the rear seats or the little 12v? Why would someone assume my traction battery is going out based of this scenario?

    Anyone else want to give some input on which 12v to replace mine with other than below:
    [​IMG]
    $169 Optima Battery DS46B24R
    Part Number: 8171-767
    575 Amp / 450 Cold
    (free shipping)
     
  11. SteveLee

    SteveLee Active Member

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    Could there be some confusion here? I'm not sure how the HV battery (High Voltage Traction battery) came up in this discussion about the 12v battery.
     
  12. Justdidit

    Justdidit LVNPZEV

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    Agreed... or how the HV battery could be going bad if its showing fully charged more...NOT the opposite - drained.

    FYI... i got a new full tank of gas last night from the exact same gas station - MPGs are back up closer to normal!! :confused: - Bad batch of gas!? It was raining pretty bad the last time I got gas, maybe water was getting into the underground gas station storage tanks? ....I'm still going to look into replacing my 12v regardless....
     
  13. SteveLee

    SteveLee Active Member

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  14. Justdidit

    Justdidit LVNPZEV

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    (y) Yup, Did that - but good to know that I don't have to 'Flash' my HIDs and can just use the parking lights!.. :)

     
  15. SteveLee

    SteveLee Active Member

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    Based on the voltchart.gif above, your battery is in less than a 50% state of charge with no load. I believe that qualifies as a bad battery for this car, though many garages, part shops, and even Toyota dealers would say it's fine. It has been reported many times here that replacing it eliminates their reported problems.
     
  16. Justdidit

    Justdidit LVNPZEV

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    Appreciate the input. Plan on swapping it out. Just would like a bit more input on the better battery... or is the Optima Yellow top undisputed?
     
  17. Justdidit

    Justdidit LVNPZEV

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  18. techntrek

    techntrek Member

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    Just got the Optima for my wife's car last week but haven't put it in yet (will tomorrow). I sourced it from Learning Aid which is recommended by many around here. Mine is an 08 too, and bottom line, I've never had a lead-acid battery in automotive service last more than 5 years so coupled with drop in mpgs and low voltage readings I think we both have the same problem. And no, you don't have a problem with your traction battery from your description.
     
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  19. Justdidit

    Justdidit LVNPZEV

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    Thanks!
     
  20. SteveLee

    SteveLee Active Member

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    It has been a preferred replacement with a little higher capacity though there have been recent reports of faulty ones, especially from local auto parts stores. It would need to be checked at the store for a full charge. I would probably consider this one if I could be satisfied with the SOC. Ordering from the company may be worth considering. And there is always the OEM from Toyota. There is also the Exide that has apparently come out with a replacement but I have not heard any experiences with this one yet.
     
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