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Does keeping a fob in the car 24/7 run down the battery?

Discussion in 'Gen 3 Prius Main Forum' started by Johnny Cakes, Jan 4, 2020.

  1. Johnny Cakes

    Johnny Cakes Senior Member

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    The post below is from one of the sub-forums. Since I often keep the fob in the car 24/7 unless I am parked in a sketchy area, I wonder whether this is true. I did have a recent battery issue, but could be a coincidence.

     
    #1 Johnny Cakes, Jan 4, 2020
  2. Grit

    Grit Senior Member

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    Yes
     
    #2 Grit, Jan 4, 2020
  3. bisco

    bisco cookie crumbler

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    if the sks is on, the system is drawing power. you could shut it off (carista? settings in the mfd? not sure)

    or you could take the battery out.
     
    #3 bisco, Jan 4, 2020
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  4. Johnny Cakes

    Johnny Cakes Senior Member

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    Interesting. That got me Google searching and I came up with the article below. But if the "proximity key system" is turned off, it would have to be turned back on to start the car. Major hassle.

    Also, I wonder how much a draw we are talking about if the key is left in the car.....


    Do electronic key fobs drain your car battery?

    [​IMG]
    Mike Allen    , Senior Automotive Editor, Popular Mechanics magazine and Master Auto Technician
    Answered Jul 12, 2019 · Author has 185 answers and 573.6k answer views


    If you have a proximity key, the kind where all you have to do is walk up to the car with the keys in your pocket, they can.

    This particularly an issue with the Toyota Prius, which uses a very small 12v battery compared to a non-hybrid vehicle. Owners were reporting dead batteries after the vehicle had been parked for only a day or two. Here’s the scenario:

    You park you car, and the radio in the lock listens for your key fob. Normally, this doesn’t use very much current, so no problem. The system can detect a key fob 40–50 feet away.

    When a key fob (any key fob) walks by, the proximity key system wakes up and tries to determine if the key fob is your key fob. This uses substantially more current, as the key fob attempts to negotiate with the car to unlock the door. Again, not usually a problem.

    Park the car in a parking ramp near a stairwell, or worse yet near the bus stop at the airport long-term lot. See where this is going? There are hundreds of key fobs passing bay all the time, and the current drain becomes significant.

    Toyota had a Technical Service Bulletin about this a while back. The remedy is to turn off the proximity key system in software if the car is going to be parked for longer than a few hours in a high-traffic location.
     
    #4 Johnny Cakes, Jan 4, 2020
    Last edited: Jan 4, 2020
  5. sam spade 2

    sam spade 2 Senior Member

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    Let's talk about the REAL issue here:
    Leaving your keys IN the car, regardless of what kind of "key" it is.

    Can't get much more stupid than that.
    It's only a matter of time before you pay the price.
     
    #5 sam spade 2, Jan 4, 2020
  6. RRxing

    RRxing Senior Member

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    Not that leaving the fob in the car is a good idea to begin with, there's this from the 2010 owner's manual (p. 49):

    Screen Shot 2020-01-04 at 6.24.30 PM.png
     
    #6 RRxing, Jan 4, 2020
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  7. Grit

    Grit Senior Member

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    I still have a spare key to an old car that I don't own anymore in my glove box, does that count as stupid? It's part of the "regardless of what kind of key it is."
     
    #7 Grit, Jan 4, 2020
  8. TMR-JWAP

    TMR-JWAP Senior Member

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    Sam,

    Not everyone lives in Shitburg, USA. Some people actually live in areas where it's not that big of a concern. And Can't get much more stupid than that merely reflects your opinion or habits you developed due to your life and location(s), not his or mine or anyone else. It reflects worse on you than the one you're directing it toward.
     
    #8 TMR-JWAP, Jan 4, 2020
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  9. Grit

    Grit Senior Member

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    Someone else (besides me) actually read the manual!!!
     
    #9 Grit, Jan 4, 2020
  10. Grit

    Grit Senior Member

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    When I had attached secured garage for my car, I always left the my car keys in the car, parked in the garage. I'm in the stupid category also heh.
     
    #10 Grit, Jan 4, 2020
  11. bettergolf

    bettergolf Active Member

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    Let's talk about the REAL issue here:
    Leaving your keys IN the car, regardless of what kind of "key" it is.

    Can't get much more stupid than that.
    It's only a matter of time before you pay the price.


    OP never asked anyone's opinion on how smart or not smart it is to leave a key in the car. Or any opinion on anything. He only asked if it will run down the battery.....a technical question. Why can't we just answer him and leave it at that?
     
    #11 bettergolf, Jan 4, 2020
  12. Johnny Cakes

    Johnny Cakes Senior Member

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    Would you say that to my face in real life?
    Enough said.

    In the area where I live, there has not been a crime in the 20+ years we have lived here. We don't lock our front door either, even when we are not home. And while we don't lock our garage (with the Prius inside with the key left in it), I guess you'd need the garage door remote to get in. :)
     
    #12 Johnny Cakes, Jan 4, 2020
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  13. sam spade 2

    sam spade 2 Senior Member

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    No......but posting THIS question certainly counts.
    Maybe even more so.
     
    #13 sam spade 2, Jan 5, 2020
  14. sam spade 2

    sam spade 2 Senior Member

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    Apparently you "can't fix" those who defend it either.
     
    #14 sam spade 2, Jan 5, 2020
  15. sam spade 2

    sam spade 2 Senior Member

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    Apparently you haven't been doing this "forum thing" very long, have you ??
    :ROFLMAO:
     
    #15 sam spade 2, Jan 5, 2020
  16. sam spade 2

    sam spade 2 Senior Member

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    Sure. Why not ? I believe it to be true.......that it is not a wise thing to do.

    And you list your "area" as Washington DC.
    I thought that they consistently come in among the top 20% of crime stats every year.

    But regardless of your "area", it still is not a smart thing to do.
     
    #16 sam spade 2, Jan 5, 2020
  17. bettergolf

    bettergolf Active Member

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    Wow Sam Spade.....what a pompous A$$
     
    #17 bettergolf, Jan 5, 2020
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  18. Hybrid Ron

    Hybrid Ron Junior Member

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    Technically true, but I think the car disables the SKS system after 10 or 15 minutes of "seeing" the key, so the drain would be limited to just that period of time.

    Wow, tough crowd. I had thought this forum was more civilized.
     
    #18 Hybrid Ron, Jan 5, 2020
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  19. sam spade 2

    sam spade 2 Senior Member

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    Not really.
    People tend to give you the advice they think you NEED rather than what you asked for.
    If you keep an open mind, that can be a good thing.
     
    #19 sam spade 2, Jan 5, 2020
  20. Grit

    Grit Senior Member

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    Another user posted on another post that once the missing key fob in the car was located, and removed from the vehicle, the 12v battery mystery going dead ended. Since you have only 1 post, I will give you plenty of time to search for his/her post. And it was only a "yes" or "no" answer that the poster wanted, no conditional answers were needed as it was addressed to us.
     
    #20 Grit, Jan 5, 2020
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