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New Optima 12V Battery - Necessary to Charge First?

Discussion in 'Gen 2 Prius Main Forum' started by Kizzy, Sep 4, 2017.

  1. Kizzy

    Kizzy Member

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    Thanks Mendel. I haven't installed the battery into the car yet. Hope to do so tomorrow. Per Sam Spade's suggestion, I'm going to see at what voltage the battery is resting after 12 hours off the charger. That will be tomorrow morning.

    As of late this evening, it has dropped a little further to around 13.25V, so it's getting very close to Optima's official specs of 13.2V fully charged for a Yellow Top battery.

    So, at the moment at least, signs are positive that the battery is healthy after all, and that it simply needed a top off from the 12.6V it was resting at when purchased.

    Will update again in the AM...
     
    #41 Kizzy, Sep 6, 2017
    Last edited: Sep 6, 2017
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  2. dolj

    dolj Senior Member

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    If you haven't found out already, looking at the battery from the front of the car toward the back, the connecting elbow twists about 45º anti-clockwise and then pulls out. It is a bayonet type arrangement. I don't know if the Optima has the same, but I guess you will find out.
    No.
     
  3. Sam Spade

    Sam Spade Senior Member

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    NO. Like I said earlier, there is NO one single magic number for all AGM batteries.
    As long as it stabilizes at 12.9 or above, you should be good to go.

    8 hours is plenty to leave it sit and stabilize.
     
  4. Kizzy

    Kizzy Member

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    Understand completely, thanks.
     
  5. Kizzy

    Kizzy Member

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    So as of this morning, about 9 hours off the charger, the Optima is reading 13.19V on my Fluke MM. :)

    Looks like I'm good to go!
     
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  6. bisco

    bisco cookie crumbler

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    perfect, well done!(y)
     
  7. iplug

    iplug Senior Member

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    FWIW, I bought the same battery from Pep Boys yesterday and they installed it without any time on a charger. Resting voltage about an hour after drive home was 13.3.

    12.8V this morning about 17 hours later.
     
    #47 iplug, Sep 6, 2017
    Last edited: Sep 6, 2017
  8. Kizzy

    Kizzy Member

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    That is interesting. From the many posts I've read, the "delivered" resting voltage on these batteries can vary widely. Just curious, how did you measure the 13.3V? Was it via the system check on the MFD? Or did you test with a multimeter at the jump points in the engine compartment?
     
  9. iplug

    iplug Senior Member

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    Multimeter at the battery terminals. (2012 plug-in Prius, so battery in the hatch).
     
  10. Kizzy

    Kizzy Member

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    Thanks, bisco! I'm going to be installing the battery after work today.

    One last question - after the battery is installed, and it's time to power up the car for the first time, should I expect to see warning lights or any notifications pop up on the dash or MFD? Or is it usually a "clean" exchange? Just want to know what to expect so I don't have a freak out if/when I see lights. ;) Also do you recommend I start off by testing it in ACC (single press) or IG-ON mode (double press) before powering up the car with my foot on the brake?

    Yes, I do tend to overthink things. But hey...this is PriusChat, so it's to be expected. :)
     
    #50 Kizzy, Sep 6, 2017
    Last edited: Sep 6, 2017
  11. Kizzy

    Kizzy Member

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    Good to know, thanks. Sounds like you got a good battery. Very glad I took the extra step to charge mine.
     
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  12. dolj

    dolj Senior Member

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    You can go straight to making the car READY. You may have to press the start button twice, is all, if it doesn't go to READY on the first press.
     
  13. dolj

    dolj Senior Member

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    More important information would be what was it out of the box? It would not be at resting voltage after an hour, and 12.8 V is more likely where its resting voltage was.
    This is exactly the reason that we advise charging up to full before installing.
     
  14. Mendel Leisk

    Mendel Leisk Senior Member

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    Now that you've got the bug, look up Solar BA5... :sneaky:
     
  15. iplug

    iplug Senior Member

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    Battery still 12.8 V a couple hours later. 2 hour ride today and same tomorrow.
     
  16. Sam Spade

    Sam Spade Senior Member

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    YOU need a good charge too.
     
  17. bisco

    bisco cookie crumbler

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    mine is 12.7 after 5 1/2 years.
     
  18. fotomoto

    fotomoto Senior Member

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    Hatch open/dome lights on?
     
  19. iplug

    iplug Senior Member

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    Yes, hatch light on with hatch open and the two dome lights in the front.

    I should clarify as well, when I first got home from the battery install I charged the plug-in battery for an hour then within minutes took the first 13.3 V reading off the 12 V battery yesterday. Seems to have stabilized at 12.8 V after.

    Agree, but it's a little different in the plug-in Prius. I purposely did not charge the vehicle last night to see where voltage would settle out. The plug-in charges the 12-volt battery when charging the plug-in battery (something I normally do every night), so it gets extra pampering in this model. Between plug-in charging and driving, I'll be putting in about 6 hours of 12-volt battery charge in the next 24 hours.
     
    #59 iplug, Sep 6, 2017
    Last edited: Sep 6, 2017
  20. dolj

    dolj Senior Member

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    It is just shame that new 12 V AGM is apparently not able to achieve full capacity. However, with the way the Plug-in works charging the 12 V, it still should go for what most people think is normal battery life. That is better than what happens for most cars.