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My 12v battery died - and yours might, too.

Discussion in 'Prime Audio, Electronics, and Infotainment' started by Inspectorman, Nov 11, 2022.

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  1. Inspectorman

    Inspectorman Junior Member

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    I use my 2018 PP almost exclusively on the drive battery. Rarely do I go past the battery range and the ICE is used. Well, something happened yesterday that I found I need to share. I'm in the car listening to the radio while my wife was doing some shopping and a message popped up on the screen that said my 12v battery was low. What!?! So I turned off the radio. When my wife arrived and tried to start the car, things went crazy. All of the display indicators started flashing - then they went dim and then so dim you could barely see them. Scary!!

    We called AAA and they arrived and gave us a jump. The car acted normal and we went home. Looking to see where I could purchase a battery, it was apparent that I'd better go to the dealer. There are a lot of systems that needed to be reset and I wanted some sort of warranty for my car. I put a trickle charger on my battery for a few hours to help insure we made it to the dealer.

    When the car didn't start - I immediately thought about why wasn't my 12v battery charged? Doesn't my car charge that battery when I'm plugged in charging the drive battery? Does that mean my car only charges the 12v when the ICE is running? There are a LOT of things that use the 12v battery and I find Toyota missed something if that battery is only charged when using gas. Scary!!

    I asked the service adviser at the dealership this morning about this and ....all I got was a blank stare.

    So - I'm sure this will never happen to me again as I plan to give the battery a little trickle charge every couple of months. But - if it hasn't happened to you - think about charging your battery on occasion and/or purchase one of those portable jump things. Hope this helps you!!
     
    #1 Inspectorman, Nov 11, 2022
  2. fotomoto

    fotomoto Senior Member

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    Screen Shot 2022-11-11 at 10.09.45 AM.png
     
    #2 fotomoto, Nov 11, 2022
  3. bisco

    bisco cookie crumbler

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    1) prime puts a fairly massive drain on the 12v when the car is off
    2) the 12v gets a very minimal charge while the car is charging
    3) the inverter charges the 12v when the car is 'ready', so it does not matter whether you are dring ev or hv
    4) the engine charges the hv battery if you run out of wall charge
    5) never use any accessories (radio, etc.) while in acc mode. only when the car is 'ready'
    6) never go thru a car wash with a low hv battery
    7) it is a good idea to ues a smart charger
    8) there are several very good threads here regarding the prime 12v 'problem'
     
    #3 bisco, Nov 11, 2022
    Inspectorman, Salamander_King and davecook89t like this.
  4. davecook89t

    davecook89t Senior Member

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    Were you in Ready mode when you were listening to the radio? If you were in Accessory mode and are in the habit of listening to the radio in Accessory mode, that could explain why your battery appears to have failed prematurely.
     
    #4 davecook89t, Nov 11, 2022
  5. CR94

    CR94 Senior Member

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    Because simply having Accessory mode engaged, even with no accessories operating, consumes several times more current from the battery than the radio itself does.
     
    #5 CR94, Nov 11, 2022
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  6. Mendel Leisk

    Mendel Leisk Senior Member

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    We do about 3000 kms yearly; car often sits for upwards of a week. The drives that punctuate the down times do tend to be good drives, not just a few blocks to the store.

    Current battery is an Optima Yellow Top, installed Sept of 2015. Simple measurement of voltage, after driving it yesterday, it's at 12.8 volts. 'Course it LIVES on a CTEK 4.3 smart charger, hooked up any day the car isn't being used, and left on.

    Presumably with the car not in "Ready" (fully on)? Never do that.
     
    #6 Mendel Leisk, Nov 11, 2022
    davecook89t likes this.
  7. MikeDee

    MikeDee Senior Member

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    If you leave the car for a week or more, that can drain your battery to where it won't start the car due to parasitic loads on the battery. Don't leave it plugged in under these conditions as it will drain the battery even faster. Probably a good idea to get a battery charger that can maintain the battery under long times of disuse. This becomes even more important if your battery is a few years old, as it has lost capacity.
     
    #7 MikeDee, Nov 12, 2022
  8. aaf709

    aaf709 Ravenpaw of ThunderClan

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    I broke my hip back in July. My boss drove it to my house, where it sat for 5 weeks. It started up right away, probably because the car was only a few months old.

    It happened twice in my 2005. The first time I spent a while getting access to the battery, the all the AAA guy did was connect to a couple of places under the hood to start it up.
     
    #8 aaf709, Nov 12, 2022
    Last edited: Nov 12, 2022
  9. Inspectorman

    Inspectorman Junior Member

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    I was in accessory mode. The battery was original to the car (2018) and I'm sure that didn't help, either. Thanks for your reply!
     
    #9 Inspectorman, Nov 13, 2022
  10. Salamander_King

    Salamander_King Senior Member

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    Yeah, ACC mode is a 12v battery killer. I don't even know why the car has that mode available. Short trips only did not help either. With my experience you need at least minimum of 1 hour READY Mode to keep the battery topped off.

    Posted via the PriusChat mobile app.
     
    #10 Salamander_King, Nov 13, 2022
  11. Diemaster

    Diemaster Active Member

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    The ONLY time I use ACC mode is if I need to power back up after shutdown. For. Ex. to roll up or crack the windows on a hot day. If you siting in the parking lot just use READY mode.
     
    #11 Diemaster, Nov 14, 2022
  12. jzchen

    jzchen Newbie!

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    If you take a look at the 12 V battery you’d probably realize why, it’s kind of small….


    iPhone ?
     
    #12 jzchen, Nov 14, 2022
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