Key Battery Low

Discussion in 'Gen 4 Prius Care, Maintenance and Troubleshooting' started by Go-Green-Pal, Nov 28, 2021.

  1. Go-Green-Pal

    Go-Green-Pal Member

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    I have a 2018 Prius 3. About 3 days ago, I saw a message saying "Key Battery Low - Replace it". I have a few questions about it.

    1. Is it something easy enough that I can do it myself. If so, what is the battery I should purchase and where will it be available?
    2. How long will the battery last once I get the message? Is it safe to assume that things will work fine at least one more month?
    3. Will I get a dire warning at some point of time saying "change it now or you will be in trouble very soon" or something like that?

    Thanks for your help.
     
  2. bisco

    bisco cookie crumbler

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    1) yes, the procedure and battery model are in your manual, and amazon, cvs, wherever button batteries are sold

    2) another 3-4 years. there is also a safety start method in your manual if the battery dies completely. but you should test the mechanical key in the door

    3) no, it will just keep reminding you until you change it

    4) all the best!(y)
     
    #2 bisco, Nov 28, 2021
    Last edited: Nov 28, 2021
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  3. bisco

    bisco cookie crumbler

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    this might help:
    watch
     
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  4. alanclarkeau

    alanclarkeau Senior Member

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    Mine had that message 6 months ago - so I bought a pack from the SUPERMARKET. They're still in the car, one day I'll change both FOBs. Instructions are in the OWNERS MANUAL - takes 2 mins.
     
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  5. Go-Green-Pal

    Go-Green-Pal Member

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    That is surprising (especially considering it took slightly less than 4 years to get the battery low message in the first place). Are you sure it lasts that long after the battery low message comes? Perhaps you are telling me the total life of the battery.
     
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  6. Go-Green-Pal

    Go-Green-Pal Member

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  7. bisco

    bisco cookie crumbler

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    sorry, senior moment :oops: yes, for a new battery. it cannot be determined how long it will last once you get the message, but it will always start the car.
     
  8. alanclarkeau

    alanclarkeau Senior Member

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    Mine gave the message about 5yrs old - but I've only used it for about ½ that time - I had the battery out of the 2nd FOB for 2½ yrs, then swapped FOBs - taking the battery out.

    It would be a combination of battery age and battery use which causes it to degrade. New batteries were cheap.
     
  9. jerrymildred

    jerrymildred Senior Member

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    What a slowpoke! :LOL::LOL:
    Last time I changed one of those I timed it. It took all of 14 seconds. :whistle: (Not counting the extreme effort involved in getting the battery out of the ridiculous packaging.)
     
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  10. alanclarkeau

    alanclarkeau Senior Member

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    OK - I said 2 mins - but that was sort of a guess. I didn't time myself. But I think it was slightly more than 14 seconds - I'm old and slower. Probably sipping coffee while doing it too.
     
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  11. Mendel Leisk

    Mendel Leisk Sand Pounder

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    How are the fourth gen fobs?

    My impression changing the battery on our 3rd gen: the innards are surprisingly exposed and fragile looking, once you've popped the case open. I'd much prefer if there was a little cover, just for the battery, and the circuit board and the rest of it stayed covered.
     
  12. CooCooCaChoo

    CooCooCaChoo Active Member

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    Pretty much the same. Circuit board inside clam shell.
     
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  13. jerrymildred

    jerrymildred Senior Member

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    My 14-second time was for a 4th gen. You do have to be careful that it doesn't spew its internals all over the table. There's a 25 second penalty if that happens. :D
    This time I videoed the process. I didn't really rush this time. Still under a half minute.
     
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  14. fuzzy1

    fuzzy1 Senior Member

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    ... and you probably counted the time needed to get the new battery out of its @$E#%! packaging.
     
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  15. jerrymildred

    jerrymildred Senior Member

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    What is it with those battery packages?? Talk about child-proof over-kill.
     
  16. MIkeDr

    MIkeDr Active Member

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    Wasn’t there an issue with kids swallowing these batteries thinking they were candy or something?
     
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  17. jerrymildred

    jerrymildred Senior Member

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    I'm sure that it's to keep kids from swallowing them, but I don't know of any other object that size that's that hard to get out of the package.
     
  18. alanclarkeau

    alanclarkeau Senior Member

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    Mine looks easy - but isn't!!! The battery <POPS> out - but then needs a pair of scissors to get to it.

    upload_2021-12-3_16-5-39.png

    upload_2021-12-3_16-6-44.png

    ANYONE know where the scissors are?????????
     
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  19. Hidyho

    Hidyho Senior Member

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    Taste one, heard they even added a bad taste to them to try to get kids to not put them in their mouth. LOL
     
  20. Go-Green-Pal

    Go-Green-Pal Member

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    I was being lazy and just switched to my spare key fob instead of actually changing the battery. Since my previous key fob lasted over 3.5 years, I thought I probably won't have issues for another 3.5 years. To my surprise, this spare one lasted only one month or so and then again, I started getting the same "low battery in key fob" message.

    Finally, I moved my lazy nice person and went to store bought new battery and changed in both the fobs. As all of you said it is very easy and did not take much time.

    So, anyway this means it looks like the battery will be decaying even if you are not using the fob (maybe I should not have replaced the battery in second fob, since I am not using it - it will unnecessarily decay now).
     
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