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My Key Fob Battery Story

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by CaliforniaBear, Aug 24, 2022.

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  1. CaliforniaBear

    CaliforniaBear Clearwater Blue Metallic

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    I purchased my Prius Plug-in March 2013; it was built in July 2012. I closely watched this group for the first few years. Folks said that key fob battery might need replacing after a few (?) years. So, after about 2 years I replaced the battery in in the key fob I had been using and bought 2 extra batteries. In spite of the caution about not keeping the key fob in the car; mine is always there except when away from home, so that is 99% or the time. Just today I was getting a red warning light at the right side of the display. It looked like it might have to do with the key fob battery, so I replaced the battery with one of those purchased 8 years ago and the warning light went away. The backup key fob didn't work at all even though it had pretty much never been used. I installed the other battery, and it works too. So, the warning about having spare batteries was very helpful, the one about not leaving it the car all the time, not so much. The shelf-life of batteries these days is amazing. I just ordered 2 more that I may never use.
     
    #1 CaliforniaBear, Aug 24, 2022
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  2. ChapmanF

    ChapmanF Senior Member

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    I waited for my Gen 3 to say REPLACE KEY FOB BATTERY on the MID, and then I stopped at a store and bought one and replaced it.
     
    #2 ChapmanF, Aug 24, 2022
  3. bisco

    bisco cookie crumbler

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    i wonder if leaving the fob within range puts any drain on the 12v?
     
    #3 bisco, Aug 24, 2022
  4. CaliforniaBear

    CaliforniaBear Clearwater Blue Metallic

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    #4 CaliforniaBear, Aug 27, 2022
  5. CaliforniaBear

    CaliforniaBear Clearwater Blue Metallic

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    Well... the little indicator light but that is virtually nothing. I believe the car continuously "looks" for the key. Perhaps it does something when it gets a response from the key but I can't imagine that is any meaningful drain. The real concern, and reason for this discussion is how long the key battery lasts when it is responding every time.
     
    #5 CaliforniaBear, Aug 27, 2022
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  6. rjparker

    rjparker Tu Humilde Sirviente

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    There are timers that reduce the pinging under certain conditions. The shortest is ten minutes if the fob is left in range.

    BC933DDC-D003-4A58-B1DE-0637209D0AFF.jpeg Of course you can manually shutoff the smart key system if longterm airport or similar parking is planned.
    0B4003CC-991B-4532-ABB5-D4F63EF8FA69.jpeg
     
    #6 rjparker, Aug 27, 2022
  7. CaliforniaBear

    CaliforniaBear Clearwater Blue Metallic

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    Yes, I remember reading about that. It doesn't relate to my situation. I use the car almost every day. My key battery should be good for another 6 to 8 years :)
     
    #7 CaliforniaBear, Aug 27, 2022
  8. bisco

    bisco cookie crumbler

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    we typically get 4-5 years, but the keys are about 15-20' from the cars
     
    #8 bisco, Aug 28, 2022
  9. Sarge

    Sarge Senior Member

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    I assume you live in a small town or remote area where theft is less of a concern, but are you sure this is a good idea? I would think your insurance company would not be happy to know this, particularly since you have advertised this on the internet (assuming someone could figure out your real identity… o_O). Just food for thought.

    Some good discussion here, my understanding is keeping a fob closer to the car can only drain the fob battery quicker than necessary, so best to keep it at least ~10ft away if possible.

    Also, a couple other tips.. there is no need to change the fob battery prematurely, as even a dead fob can start the car, by holding the fob in front of the start button and pressing Start (the fob has an RFID-like technology that can work without a battery.) There is an emergency mechanical key in the fob to open the driver door, in the case of a dead battery in either the fob or the 12v.

    Lastly, the fob has a built-in low battery detector.. First, the car will tell you when the fob is low, but if you look at the fob, there is a small red light which illuminates when you press a button; when the battery is low, the red light will NOT come on, as an indicator of the low charge status.

    I have changed my fob batteries (CR1632) a couple times; I recommend sticking with a brand like Duracell or Energizer… I tried some of those cheap Chinese batteries off Amazon, but found they never last more than a couple months…:mad: You get what you pay for…
     
    #9 Sarge, Sep 3, 2022
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