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my 2020 Prime in need of new 12V just went all dark.

Discussion in 'Prime Main Forum (2017-2022)' started by The Big Sleaze, Nov 9, 2024 at 6:06 AM.

  1. The Big Sleaze

    The Big Sleaze Member

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    Location:
    'frisco
    Vehicle:
    2020 Prius
    Model:
    Two Eco
    Every once in a while I would say "low battery" and would be fine after a jump.

    This last time, it was all dark except for a few blinks, and thought maybe it was Key Fob so replaced that battery. Then I hooked up my portable jump starter and even without trying to start normally, a bunch of stuff in engine bay started coming alive. Then my jump starter went from green to red, and engine bay got quiet. Re-try jump starter but only reads red. EVERYTHING including Electric door locks now dead!

    Is this just it telling me "you REALLY need a new 12V" and that will fix it, or is their some fuse or something that might need attention?

    Car has about 105K and its about 60days from its 5yr birthday, so new battery is about right on schedule.

    Anything I should know about new 12V for this car? Walmart or Autozone 3 or 4 year OK? Any upgrade batteries worth a look? I might start doing some extra 12V related stuff, like running laptops and even 110v converters for about 60w big computer screen, with car in "On" and hopefully charging 12v off main battery.
     
    #1 The Big Sleaze, Nov 9, 2024 at 6:06 AM
  2. BiomedO1

    BiomedO1 Senior Member

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    More than likely, your 12V battery is dead, dead! You can verify by putting a DVM on it. You should be able to override your jump-box safeties to get her started. Just make sure you don't reverse polarity it!!
    For future reference, if you have to jump start your car - you need to put the battery on a charger to get it back up above 12.75V, otherwise every time you jump-start the car your taking a bit more battery life from it. Death by a thousand cuts!!! Just driving the car around isn't going to cut it!!!
    IMHO; I always go with the cheapest battery available with fill ports. I usually get 10+ years out of them. You just need to check electrolyte levels annually around this time of year and do a quarterly voltage check for battery status. If you keep the battery above 12.25, your golden. Anytime I find the battery below 12V, I put it on a charger as stated above. It shouldn't take more than 2 hours @ 6A charge. The longer it takes to get to 12.75V, the worse you battery is - In other words it's about to fail, because it won't hold capacity....

    Hope this helps.....

    As long as you can unplug your accessories and only run them while the car is in READY mode, you should be OK. DO NOT wire anything directly to the battery - that little battery has enough issues already, without you putting more on it's plate. I think the cigarette lighter ports turn-off with the car, If they don't I'd reconfigure them, so I wouldn't get stuck somewhere.
    You've got plenty of room under your rear seat cushion, you may want to wire a backup/camping battery with an over-ride switch. It can be recharged by your DC-DC converter or AC outlet, depending on how you wire it.
     
    #2 BiomedO1, Nov 9, 2024 at 10:51 AM
    Last edited: Nov 9, 2024 at 11:23 AM
  3. The Big Sleaze

    The Big Sleaze Member

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    Vehicle:
    2020 Prius
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    Two Eco
    thx for the tips. already sprung for Walmart "3 year" battery. Looking online I can't seem to find any Re-Fillable batts on sale, I guess I'd have to ask at a semi-legit auto-parts. Seems they are Deep Cycle and lack high amps for cranking a big motor (but they were standard equipment in old days with big hi-comp engines and low tech starters), but IIRC that might be a great match for a Prius since IIRC the 12v only boots up the Brains and the ICE is cranked by gen-set off the Traction Batt, that is programed to never, ever let itself go too low.

    I've got a 9lb "Power Bank" that will run laptop, big tablet, and few other things full blast for about 24hrs total. I charges off 19v laptop plug which in turn can run off 12v cig liter. I guess I can use that as buffer.

    Maybe Toyota doesn't put long life re-fillable 12v batts in Hybrids due to Personal Injury fears. I worked at Auto Parts store once where they'd fill dry new lead batts with acid, and some guy would check old batts and re-fill, but only he was allowed to mess with that and he'd wear big goggles and gloves and apron, and had tales to tell. I had an old van with battery mounted behind driver's seat. One day a coat hanger bridged the poles and caps blew off, while I was driving! Only thing that really happened was next time I washed the shirt I was wearing it had peppering of little holes in the back above where the seat blocked the spray. People said it looked really cool and how could they make one. lol.
     
    #3 The Big Sleaze, Nov 10, 2024 at 3:50 AM
  4. BiomedO1

    BiomedO1 Senior Member

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    LE
    My 2021 Prime 12V battery has access ports. Use a nickle or large screwdriver to unscrew the caps.



    Wearing apron, goggles, and gloves was an insurance and safety issue for employers. You just need to be careful handling the battery acid. How many times have you seen pool cleaner taking those precautions. I remember having to use muriatic acid to balance pool chemistry in one of my high school jobs - I was afforded no such protections. Every once in a while my arm would get itchy and I'd realize I've caught some acid splash. I would occasionally find small holes in my shirts and trunks too. After a while thinking about this, I just jumped into the pool after rebalancing the chemistry. No more issues. I guess we just believed in Darwin's philosophy back then and take responsibility for your own actions - rather than blame other people.:p:confused::whistle:
     
    #4 BiomedO1, Nov 10, 2024 at 9:15 AM
    Last edited: Nov 10, 2024 at 9:25 AM
  5. bisco

    bisco cookie crumbler

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    keep an eye on the 12v, as the prime does a poor job of keeping it charged. a maintainer when not driving is helpful
     
    #5 bisco, Nov 10, 2024 at 1:48 PM
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