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12v battery health observation

Discussion in 'Gen 4 Prius Technical Discussion' started by Elt31987, Apr 13, 2020.

  1. Salamander_King

    Salamander_King Senior Member

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    Yeah, after watching the video on comment #2 by Prof. Kelly at WSU. I now want a Fluke 87 Series V multimeter. And he has THREE of them in his arsenal. But... That's gonna cost me a lot... :cry:

    Screenshot 2020-04-20 at 3.17.07 PM.png
     
  2. jerrymildred

    jerrymildred Senior Member

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    I used the Fluke 87 in the can factory and at the radio station. Really nice meter. But probably overkill unless you're using it professionally.

    When the Fluke at the radio station died, we got an Amprobe and I was just as happy with it for a considerably better price. Can't remember which model it was, but it was true RMS plus lots of other features. Might have been this one. Looks like it anyway.


    At home, I'm very happy so far with my Klein CL380. It's a clamp on meter that also does DC current.
     
    #42 jerrymildred, Apr 20, 2020
    Last edited: Apr 20, 2020
  3. sam spade 2

    sam spade 2 Senior Member

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    Come on, what exactly ??
    AGM batteries in general are known to last MUCH longer than conventional wet cell ones, especially when the owner completely neglects checking the electrolyte level in the old style ones.
    Twice the life is NOT out of the question.
     
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  4. sam spade 2

    sam spade 2 Senior Member

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    Because they can save $20 per car by putting the cheaper kind.
    There are NO circumstances that I am aware of where an AGM is not a better choice.
     
  5. Raytheeagle

    Raytheeagle Senior Member

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    I bet you're jealous :p.

    Life favors the prepared (y).
     
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  6. bisco

    bisco cookie crumbler

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    the wet cell 12v in my '05 dakota is still humming along nicely. i've never checked the water.

    what a shame we have to spend so much time and money monitoring the health of the prius 12v (n)
     
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  7. alanclarkeau

    alanclarkeau Senior Member

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    Oh, dear - I must be neglectful - mine is about to have her 4th birthday, and I've never thought about it - apart from when, a couple of years ago, I left the lights on. It wouldn't start, but I left it for a few hours and there was enough charge for it to start again.
     
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  8. jerrymildred

    jerrymildred Senior Member

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    'Scuse me. Gotta go make sure my lug nuts are still tight. :whistle:

    The only reason I've paid any particular attention to mine is as a participant in threads like this one. And maybe a little more now that I'm not driving as much, which would be the case with any car. My extra attention consists of the little voltage monitor I plugged into the 12V outlet.
     
  9. Elt31987

    Elt31987 Active Member

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    I threw it on the float charger overnight. Took it off the charger and my Klein MM400 meter says 12.71 and the Topdon tester says 12.74. Ill go check the voltage in about 8 hours and then rerun the Topdon test. The acid level is all the way up to the top line as well
     
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  10. Elt31987

    Elt31987 Active Member

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    Let it sit 8 hours

    Klein MM400 says 12.51v
    Topdon says 12.52
    Ran the test on it:
    Topdon:12.52v
    340CCA
    9.76 ohm
    SOH: 100%
    SOC: 86%
    Klein MM400 after test: 12.5

    Im going with this thing has plenty of life left in it. Im also suspecting that the Prius doesnt charge it all the way under normal operation. Im still curious if someone else can drive theirs a good ways and then check the voltage right after turning the system off and then 8 hours later after.
     
  11. bisco

    bisco cookie crumbler

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    well done, agreed. you're in good shape for awhile. i just don't think any prius will charge a battery to full in 40 miles.
    8 hours is the recommended, which is at least 250- 320 miles.

    but if you're driving more regularly, it doesn't drop down much.
     
  12. Elt31987

    Elt31987 Active Member

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    Would that be to charge a battery from empty to full? or from say 50% + to full?
     
  13. bisco

    bisco cookie crumbler

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    idk. and it's an old suggestion for gen2, so it's probably a little different. i do know (from reading here) that all prius are designed to maintain voltage, and struggle to do more than a little charging.
     
  14. sam spade 2

    sam spade 2 Senior Member

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    Well you aren't really done yet.
    If it stabilizes at 12.5, you're fine.
    BUT if it continues to drop a tenth or more per 8 hours, then you have a problem.
    That means that it will take about 3 days or less to reach 50% discharged and that is NOT fine.
     
  15. Elt31987

    Elt31987 Active Member

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    Ill recheck in the morning then. That will give it 24 hours. The key hasn't gone near it and only the inside dome light was on for maybe 10 minutes while i sat in the passenger seat.
     
  16. sam spade 2

    sam spade 2 Senior Member

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    Maybe others will know for sure but I think other things might "wake up" when the dome light is triggered.
    If you were there only to measure battery voltage, why were you even inside the car ??
     
  17. Elt31987

    Elt31987 Active Member

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    Cleaning out the car. Kept the key upstairs and didnt open the drivers door so who knows
     
  18. Elt31987

    Elt31987 Active Member

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    So 24 hours, the Klein says 12.37 volts. So maybe its draining too fast lol. We'll see. Im 100% remote and have a portable jumper in case it decides to not start and my wifes car. Ill leave it on the float charger in the garage for now.
     
  19. Salamander_King

    Salamander_King Senior Member

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    FWIW, I am taking SOC reading on my 2020 PRIME on this tread 12v Battery Is Discharging, Re-Charge Now ! | Page 4 | PriusChat. My almost brand new PRIME has sat on PARK for 5 days now since I fully charged the 12v. I have BlueTooth Battery Monitor installed, so I can remotely monitor the 12V battery SOC 24/7 without touching the car. Initially, the fully charged battery lost ~0.1v/day for the first 3 days. It changed from 13.06v to 12.64v. But on 4th day, it changed from 12.64v to 12.62v. It seems to have stabilized. My pre-full charge reading was 12.56v 91% SOC. I have a feeling that it is not going down below that mark even if I let my car sit longer than a week. I will see.
     
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