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Canadian tire won't load test my AGM battery.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by morglum, Feb 18, 2015.

  1. morglum

    morglum Junior Member

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    Hi all,

    After charging my battery (bought last March) over 24hours, I still have a low-ish voltage reading. 12.5V on voltmeter with the battery outside of the car, but only 12.0V from the in-car display. The voltage drops to around 11.8V when turning the accessories on, and to 11.5V when trying to use the power window (which almost stops since it goes so slow..). I've seen as low as 10.5V volt this winter when it was colder.

    Anyway, I brought my battery in for a test and all he did was test the voltage without load, which returned 12.5V, which according to his test sheet is perfectly fine. According to the manual, anythign above 11.0V is fine, just charge the battery overnight.

    I told him that the voltage drops when under load, but he told me that they dont test AGM batteries under load for some reason.

    So either my battery is fine and it's normal for the voltage to drop under load, or their test is bullshit and they dont want to replace my battery.

    Anyone heard that before?

    this is at Canadian tire.
     
    #1 morglum, Feb 18, 2015
  2. GrumpyCabbie

    GrumpyCabbie Senior Member

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    Ask yourself this question; is it a 12 volt battery or a 10.5 volt battery? There's your answer.
     
    #2 GrumpyCabbie, Feb 18, 2015
  3. morglum

    morglum Junior Member

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    #3 morglum, Feb 18, 2015
    Last edited: Feb 18, 2015
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1.5A capacity from the charger isn't much. That charger is mostly useful for keeping a good 12V battery charged.

    The open-circuit voltage of a fully-charged AGM battery (after surface charge has dissipated) is 13.0V. Since your battery voltage is only 12.5V it at best is around 50% charged. It could be that your charger does not recognize that the battery is AGM and requires a higher charging voltage.

    It sounds like you are stuck with that battery for now. I would get a battery charger that has 4A and 10A charging positions and is intended for AGM batteries. Then hook the charger up using the 4A position and leave overnight. See what happens to the battery resting voltage after that process is complete and surface charge has dissipated.
     
    #4 Patrick Wong, Feb 18, 2015
  5. 69shovlhed

    69shovlhed Surly tree hugger

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    or discharge the battery good and take it back to the nice person clown at the tire store and tell him to retest it...
     
    #5 69shovlhed, Feb 18, 2015
    exstudent likes this.
  6. bisco

    bisco cookie crumbler

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    is the battery giving you trouble? what kine of warranty left on a 6 year old battery?
     
    #6 bisco, Feb 18, 2015
  7. exstudent

    exstudent Senior Member

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    +1000. Problem solved.

    Almost missed it too. OP bought a replacement in March 2014.
    What brand would be nice to know.

    Maybe update your battery charger, and donate/sell your existing charger?
    $40 Noco Genius at Newegg (sale ends 2/21); Noco seems to be a scaled down version of a CTEK
    NOCO Genius G3500 6V/12V 3.5 Amp Smart Battery Charger and Maintainer - Newegg.com=

    Ctek Multi US 4.3 ($78, Amazon); REALLY NICE charger. Has desulfating capability.
    CTEK Multi US 4.3 | CTEK Battery ChargersCTEK Battery Chargers
    Amazon.com: ctek mus 4.3

    I have the Schumacher SSC-1500A-CA. $55 at Amazon.
    3Amp/15Amp charge setting. Because we have a conventional car, w/ a traditional 12V wet cell battery, this charger was perfectly situated for both cars. Only wish this charger had the direct connect battery "pig tails" (eyelet terminals) like the Ctek, Noco, and Battery MINDer.
     
    #7 exstudent, Feb 19, 2015
  8. Britprius

    Britprius Senior Member

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    The charger you have is not man enough to charge the Prius battery in reasonable time. In fact it is not recommended for batteries over 20 AH capacity.
    The Prius OEM battery is 45 AH. As stated on page 4 of the manual it will take 20 to 25 hours to charge a 20 AH battery. To charge the Prius battery you would need to charge for a minimum of 60 hours.
    Having said all that your battery is likely to be faulty, and there is no reason why a discharge test should not be carried out. If it is an Optima using there own figures that charger will never fully charge it.

    John (Britprius)
     
    #8 Britprius, Feb 19, 2015
  9. morglum

    morglum Junior Member

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    Sorry for taking so long to reply, I didnt notice the last few replies.
    Thanks everyone for the replies. I'm going to get the CTEK and be done with it. I'll find a friend with a motorcycle to donate the small charger.

    cheers
     
    #9 morglum, Apr 10, 2015
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