AGM battery for Gen 4/Gen 5 Prius/Prius Prime and observations on the 12-V charging system

Discussion in 'Gen 5 Prius Main Forum' started by Gokhan, Sep 20, 2024.

  1. Gokhan

    Gokhan Senior Member

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    This is the rested-battery open-circuit voltage so far for the Uplus EN LN1/DIN H4/BCI 140R AGM battery:

    day voltage

    18 13.05 V
    19 12.98 V
    20 12.95 V
    21 12.92 V
    22 12.90 V
    23 12.87 V
    24 12.87 V
    25 12.87 V
    26 12.87 V
    27 12.87 V
    28 12.87 V
    29 12.87 V
    30 12.86 V
    01 12.85 V
    02 12.84 V
    03 12.87 V
    04 12.84 V
    05 12.86 V
    06 12.85 V
    07 12.80 V
    08 12.83 V
    09 12.80 V
    10 12.82 V
    11 12.84 V
    12 12.79 V
    13 12.82 V
    14 12.83 V
    15 12.80 V
    16 12.78 V
    17 12.83 V
    18 12.78 V

    For an AGM battery, about 12.89 V is 100% SOC, and about 12.78 V is 90% SOC; so, it looks like the rested open-circuit voltage has stayed above 90% SOC so far.
     
  2. RandyPete

    RandyPete Active Member

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    I never stated what my flood cell batteries SOC is. Where did you get that statement from ?

    From the data you have already posted :

    As you can see, your AGM 'rested battery open circuit voltage' (as you describe it) has been trending downward from 13.05v on day 18 to 12.82v on day 13. That demonstrated a downward trend in 'rested battery open circuit voltage'. If you continue to monitor this 'rested battery open circuit voltage' I am speculating that it will continue to trend downward if you do not put the car in ready mode. If it levels off at some point before you decide to recharge the battery to 100% SOC with an AC automatic AGM profile charger the downward trend will start off anew. Hopefully you will perform that task at a voltage of 12.3v or greater.

    Note: You are not measuring and recording a 'rested battery open circuit voltage' technically. You are recording a rested battery voltage with parasitic load. This is not an open circuit voltage, the battery is still hooked up to the Prius.

    If you would like to accelerate the downward trend in your AGM you could just continue to let the battery rest, still hooked up to the Prius, for several days, maybe a week or so, and watch the battery voltage continue in its voltage downward trend. Please do recharge it with an AC charger before it goes down to 12.3v or less.

    I will post some data from the new flood lead acid in my Prius soon.

    Yes, AGM batteries have superior performance compared to flood lead acid batteries. But both batteries need to be charged to 100% SOC regularly or they will suffer a shortened life.
     
    #62 RandyPete, Oct 18, 2024
    Last edited: Oct 18, 2024
  3. Gokhan

    Gokhan Senior Member

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    No, you haven't—I asked you to look at your flooded-cell open-circuit voltage and SOC.

    The Noco Genius 5 slightly overcharged the battery—That's why the voltage was initially so high. Typically, 12.89 V is considered to be 100% SOC for AGM. Also, initially, the car was charging the battery very aggressively, which later stopped, and the charging has become minimal lately, like literally for a few minutes a day only.

    Again, you are speculating regarding the trend in SOC. If it dropped below 12.70 V, I would probably manually charge it. But I don't think it will. It seems to have stabilized around 12.80 V. And I bet your flooded cell is doing a lot worse, probably hovering around 12.40 V, because that's what my flooded cell was doing.

    [​IMG]
     
  4. Gokhan

    Gokhan Senior Member

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    He has a battery monitor. He's right that when in the park gear, the voltage always stays at 13.53 V, no matter how long the car is run.

    It's not the voltage that charges the battery. It's the current. And an AGM cell will have a much higher current for a given voltage because its internal resistance is only 1/5 of a flooded cell.

    From what I've seen, the AGM cell charges really well. Let's see your data for the flooded cell.
     
  5. RandyPete

    RandyPete Active Member

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    Do you have an app or program (excel ?) that produces a graph like that from the date/time data and the battery voltage data ? I've been looking for one, No success yet.
     
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  6. hill

    hill High Fiber Member

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    Just replaced our 7¾-year-old OEM AGM in the 2018 plug-in minivan (manufactured September 2017. LoL - ZEEEZ the stock 12v with its 650 cold cranking amps & its replacement according to Costco needs to be 750? Who writes these nonsensical & almost stupid suggestions ?!? All it needs to do for the next 7yrs is wake the freaking ECU that tells the relays to open. Obviously - even in our environment where it sometimes hits as low as -30°f for few morning hours - the 12V AGM is going to last more than the 7 years that WE got out of the OEM. Seems the best way to test a hybrid 12v is to occasionally leave the ignition on for a few minutes, have the headlights & sterio & heater fan on to see if it pulls down quickly. Ours still didn't - for well after it's recommended 6 yrs. But airing on the side of caution, we replaced it due to its age.
    STUPID thing was, the vent tube insert hole meant the fiberglass strap running across the top of the 12 v would block inserting the plastic vent tea. Oh well, Costco's $175/3yr warranty beats Chrysler's $600 obscene price by a mile. No wonder the poor slobs at stalantis are in the red.
    If Toyota ever puts a plug in their minivan, we will be all over it.

    .
     
    #66 hill, Oct 19, 2024
    Last edited: Oct 19, 2024
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  7. Gokhan

    Gokhan Senior Member

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    Why didn't you get the Uplus AGM battery? It probably comes in your group size.
     
  8. hill

    hill High Fiber Member

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    Simple. Costco's warranty, price & convenience.
     
  9. Gokhan

    Gokhan Senior Member

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    Yes, just Excel. You can use Google Sheets with the same functionality, too, which has the advantage of being cloud-based.
     
  10. Gokhan

    Gokhan Senior Member

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    What group size was that? The Uplus AGM battery is probably cheaper. (There is a 10% coupon. There is no core return, and you can get a $10 gift card for your core from AutoZone. There is the 5% Amazon Prime rewards as well.) It comes to your door in a nice padded box.

    Uplus AGM battery on Amazon
     
  11. hill

    hill High Fiber Member

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    Between Bezos' leftist woke agenda, & Costco giving a $15 core return?
    Easy decision. Out the door $170 & $15 for returned core

    .
     
  12. Gokhan

    Gokhan Senior Member

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    Ha ha, so, you don't buy anything on Amazon and don't stream Amazon Prime video? What was your net price including the core? I would think $175 included the core. What group size was it?
     
  13. hill

    hill High Fiber Member

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    You can find most of the same Chinese junk Amazon sells Via TeeMu - so why does anyone need to enrich someone 3rd party enriching products from china.... see post #71 for price info.
    For streaming we typically use netflix & dish/Samsung.
     
  14. Gokhan

    Gokhan Senior Member

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    So, you are not going to tell me what group size it was?

    Uplus is the new-technology division of Leoch—a Singapore-based company, not a China-based one. It is one of the biggest lead–acid-battery manufacturers in the world. It is an OEM for many car companies.

    Brand introduction—Welcome to LEOCH lead–acid battery, VRLA battery, UPS battery, motorcycle battery, car battery, golf-cart battery, gel battery
     
  15. hill

    hill High Fiber Member

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    LOL stated that way it sounds like you wrongly believe you need to goad to me into confirming a size so you can assure YOU have the best deal? LOL is there some kind of misconstrued theme that I'm keeping a secret? No ... we required H6 or H7 (h6 was less) for it to fit in the Chrysler compartment which is in the rear left cabin wall. By hooking up the +/- leads to a battery charger we were able to maintain lots of personal settings which meant we (i) didn't have to spend an hour reprogramming tons of junk (seat settings - prior mpg, satelite & terrestrial radio etc) .
     
  16. Gokhan

    Gokhan Senior Member

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    Well, if you got the Uplus battery:

    Uplus AGM DIN H6: 70 Ah, 120 RC, 760 CCA, $157.49
    Uplus AGM DIN H7: 80 Ah, 140 RC, 850 CCA, $166.49

    And you get a $10 AutoZone gift card for your core return as well as the 5% Amazon Prime Visa card discount.

    The Costco Interstate AGM batteries have the same specs, but they are both $169.99 plus the refundable $15 core charge. Note that Interstate does not make batteries but resells them from OEMs. As a result, the quality varies. The Interstate MTX-48/H6 AGM ranked well (86/100) in Consumer Reports tests, but the Interstate MTX-94R/H7 AGM was the lowest-rated battery (38/100) among the DIN H7/BCI 94R batteries.
     
    #76 Gokhan, Oct 19, 2024
    Last edited: Oct 19, 2024
  17. hill

    hill High Fiber Member

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    So that's the long-winded version to say the costco/interstate H6 ain't too bad. Coupled with all of the other pluses & considerations mentioned above, that makes it even LESS of a 'not too bad' - right? Especially considering Amazon's 30-day warranty policy.
    Even that is very shaky. We ordered 1,000s of dollars of folding chairs for our church camp ground & Amazon REFUSED to pick them up (costly) so we could get a refund once they started breaking apart & the upholstery started cracking apart some 2 weeks after delivery. Costco has never been tight fisted regarding warranties. Dear amazon, BLANK you.
    .
     
    #77 hill, Oct 19, 2024
    Last edited: Oct 19, 2024
  18. Gokhan

    Gokhan Senior Member

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    In the park gear, the battery voltage stays at 13.53 V. Interestingly, in the reverse gear, the battery voltage stays at 14.10 V, which is the maximum for this system. I wouldn't leave the car unattended in reverse gear to charge the battery though.
     
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  19. Mr.Vanvandenburg

    Mr.Vanvandenburg Senior Member

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    I wouldn’t leave it in reverse unattended either. Have you priced those back up lights? Going to be $1000+ and have to remove the rear bumper.
     
  20. Gokhan

    Gokhan Senior Member

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    Yes, when they hit my bumper and broke my lamp assembly, I removed and reinstalled the bumpers to replace the lamp assembly myself. It’s not easy. It saved me a lot of money, as I pocketed the insurance payment. In hindsight, perhaps I should have replaced the No. 921 bulbs with long-life (krypton?) versions. Perhaps you could reach the reverse-gear-bulb socket from under the car though if you lift the car.

    Victim of a hit and run—again | PriusChat