12V Battery - is there a standard 'display' that shows current state

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by LFF, Jun 7, 2021.

  1. LFF

    LFF New Member

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    I am driving my 2010 Prius less and less, just had a new 12v battery installed; try to drive at least every 10 days just to keep the 12V charged. Is there a setting that I can use to display the charge status of the 12V, similar to the display that shows the charge state of the traction battery?

    Frankly, I don't worry about the traction battery - my car sat for over a year during the pandemic last year and started up fine with a jump, but the 12V battery has had to be replaced every 3 years, probably because I don't drive it often enough.
     
  2. JC91006

    JC91006 Senior Member

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    Since you're not driving the car much, I'd interested in buying the car. I'm looking for a low mileage Gen3 car and I live in So. Cal
     
  3. sam spade 2

    sam spade 2 Senior Member

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    NO. A voltmeter is needed.

    And driving it for a short time or short distance just every 10 days probably isn't enough.
    Connecting it to a battery charger or tender overnight every 10 days would be much better.
     
  4. Mendel Leisk

    Mendel Leisk Sand Pounder

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    If you don’t have available AC 120 volt access (say apartment or street parking), and the car is chronically low use, you might also consider install of a kill switch. Basically an accessible, heavy-duty breaker switch, between neg post and body IIRC.

    They ARE inconvenient; you lose radio presets and trip meters, and set some of the cars electronics back to defaults, they need to relearn, every time you reconnect. But the main reason the battery runs down is the CONSTANT low level drain when connected; it’s not much, but enough to eventually drain the battery, with days on end idle.
     
  5. sam spade 2

    sam spade 2 Senior Member

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    Well, that is only partly true.

    If bone stock, any production car should sit idle for 30 days and still start........IF the battery is healthy and fully charged going in.
    But those are two big "IFS".

    Once it has sat around idle with a low change in the battery for a while, it's health can decline rapidly.
    If you don't take care of your 12 V battery from the beginning, you can't go back and make up for that later.
     
  6. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Most any battery, after 30 days hiatus, will be knackered.

    It’s like holding your breath, doesn’t matter how big a lungful; eventually you succumb lol.
     
  7. Valiant V

    Valiant V Member

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    Wouldn't a solar battery trickle charger do the trick in this case? They put out very little current, but possibly enough to offset the drain from whatever vampire circuits are there.

    It DOES seem like hybrids suffer from early death of the 12v "accessory" battery. I was looking at a 2020 Ford Fusion and the dealer said it likely needed a new battery. The battery in our pre-owned 2017 Prius (Three) was replaced by the dealer before we bought it. It apparently had sat on the lot for a while - possibly 4 months.

    That almost sounds counter-intuitive as the 12V batteries in hybrids don't do any of the heavy-liftng like batteries do in ICE cars - especially in Northern areas like my old Chicago cars. A decently-treated battery could last 5 years with no problem even when having to start 300+CID engines at 0F. I've had a couple go ten years.
     
  8. Mendel Leisk

    Mendel Leisk Sand Pounder

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    A VW dealership local to us had most of the cars on their lot sporting solar panels in south side windshields for some time. Think they gave it up, but that does seem a good idea. Also of interest: priuchatter @MSantos did a how-to install thread on his second gen civic hybrid, at cleanmpg site.
     
  9. sam spade 2

    sam spade 2 Senior Member

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    No that just simply is NOT true.
    "Many" might be a better word but a really LOT of them will be just fine.
     
  10. meeder

    meeder Active Member

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    Those solar panels only work if the 12V outlets are always powered. If they turn off with the ignition the solar panel won't do anything.
     
  11. sam spade 2

    sam spade 2 Senior Member

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    No, not a true "trickle charger" because over time they can actually over-charge the battery and do more harm than good.
    A solar battery TENDER is what you want.
     
  12. sam spade 2

    sam spade 2 Senior Member

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    That depends, of course, on where you have the panel connected.
    For that very reason, most people connect a "pig tail" to a point that is always "HOT".
     
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  13. Mendel Leisk

    Mendel Leisk Sand Pounder

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    Yeah you need to mod the existing (not constant-on) 12 volt outlet, or wire in a new connector.
     
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  14. Grit

    Grit Senior Member

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    Since everyone is avoiding the original question...

    You hold the Info button down while you turn the headlights on and off three times. When you finish, hold the Display button down and it will close out the Service Menu and reboot the Nav.
     
  15. Valiant V

    Valiant V Member

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    I'd not worry about using a power outlet and just go right to the battery terminals with alligator clips.
     
  16. Grit

    Grit Senior Member

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    data based from cars at car dealerships not driven on a regular basis? o_O
     
  17. Valiant V

    Valiant V Member

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    Though you can get solar panels suitable for 12v applications in many sizes, the one(s) I had in mind are SO low power that I can't see them damaging a battery even if you left them in full sun for days at a time.

    The one here is 1.8 watts - that's only .15 amp. I doubt that would even actually "maintain" a battery, must less damage it by overcharging.



    That output is (I'm certain) based on full-sun. Real life is probably considerably less. Unless you have your car parked where the panel receives full sun all day long, it's hardly "always charging".

    I've got several 12v 9 and 14 Ah batteries I use around our farm for automatic chicken doors and gate openers. They have 10 watt solar panels connected 24/7/365. The only problem I have with them is not getting ENOUGH sun.
     
  18. sam spade 2

    sam spade 2 Senior Member

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    But do you know whether or not their output is regulated ?
    And do you know what the output voltage is with full sun ?

    A trickle charger won't really hurt your battery unless you ignore it and don't replenish the water that goes missing.
    If the battery goes completely dry, then you are out of luck.
     
  19. TMR-JWAP

    TMR-JWAP Senior Member

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    Does the Gen 3 not have an SKS button? From actual experimentation, I know for fact on my Gen 2s, a brand new 12v battery (SKS size) will deplete in about 6.5 weeks with SKS left active. That changes to over 9 weeks with the SKS deactivated.
     
  20. Mendel Leisk

    Mendel Leisk Sand Pounder

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    No button. So either it’s not needed, or it’s a case of “no button for you”?

    a kill switch in series on the neg cable is the bees-knees, if you don’t mind hassle and memory loss.

    Maybe good to have, for just sporadic use, say protracted airport parking. unless I’m having a brain bubble, maybe some are capable of being controlled by cell phone?? Some are available, with fob control.

    for fourth gen, with battery under hood, the manual kill switch option is 100% more accessible, comparing under-hatch-floor location of previous gens.
     
    #20 Mendel Leisk, Jun 9, 2021
    Last edited: Jun 9, 2021
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