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Key Fobs & battery life

Discussion in 'Electrics, Vacuum, Ignition and ECU' started by RichardSEL, Nov 7, 2019.

  1. RichardSEL

    RichardSEL Active Member

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    Your Mercedes:
    SL320
    Been searching for some specialist place that does Mercedes Key Fobs, particularly for R129 three button -- I've an '00MY SL320 --
    The batteries CR2025 only last for a month irrespective of use -- last pair of Duracells didn't even last beyond that -- the LED lights but dim now doesn't operate at all
    Done much searching on the interweb. Found others in other forums have complained about this too.
    So it's a common fault?
    It's not to do with the pressel switches being stuck down. Although I've not put a meter across mine (too small for the prods) they do sound click when pressed and released

    Apart from going to main agent and having my wallet raped is there any alternative? No sense in changing just the case
     
    Last edited: Nov 7, 2019
  2. rorywquin

    rorywquin Senior Member

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    That is weird. We've had MBs for years and I don't recall a battery issue on the Fobs.

    EDIT...sorry not a helpful reply..
     
  3. Wighty

    Wighty Senior Member

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    Member on here jonnysbc repairs key fobs and may be able to advise
     
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  4. AMGeed

    AMGeed Senior Member

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    Stay away from the dealers if you need new batteries. I was charged £7 20 for two Duracell 2025 batteries and got 2 equally efficient Panasonic ones for £4 from Waitrose (£3 60 actually, I get discount at all J Lewis;)) Only takes a minute to change them yourself.

    As for batteries not lasting long, I found Keyless Go fobs seem to drain batteries quickly but obviously an R129 isn't affected by this. I'd be interested to know why this is happening too.
     
    Last edited: Nov 7, 2019
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  5. OP
    RichardSEL

    RichardSEL Active Member

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    Thanks for the heads up. Is there no Private Messages facility on this forum?
    If there is then I'm being very dim for not finding it (no change there) :rolleyes:

    [​IMG]
     
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  6. Wighty

    Wighty Senior Member

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    very funny buddy . Click on members on the top bar , and then on the right search “johnnysbc”(note my amended spelling
     
  7. malcolm210

    malcolm210 Senior Member

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    As an aside it was interesting that my son’s W213 16 plate threw up a warning on the dash asking for the key battery to be changed as it was low on power quite a useful feature I thought... and yes I got the job
     
  8. OP
    RichardSEL

    RichardSEL Active Member

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    Ta... Have now gone the "start a conversation" route with JohnnySBC. Will keep this thread updated with progress or whether, from information stored on this SL320's build sheet, I've got to go the "HOW MUCH?" <cardiac> route
     
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  9. EmilysDad

    EmilysDad Senior Member

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    How does it know?

    My last 451 Smart did the same by flashing the indicators 9(?) times when unlocking & my 'new' one told my phone battery was low when it paired with it.
    Far cleverer than me :D
     
  10. John Laidlaw

    John Laidlaw Senior Member

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  11. malcolm210

    malcolm210 Senior Member

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    No idea... telemetry perhaps... son said he’d use the spare while I sourced some batteries but that was flat which caused a mini panic lol
     
  12. M80

    M80 Senior Member

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  13. sonic

    sonic Senior Member

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    Your Mercedes:
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    Poundland do a pack of two CR2025's, two CR2016's, & four CR2032's for you guessed it it £1.
     
  14. pgh13

    pgh13 Senior Member

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    I guess it senses reduced power or even shouts 'help' when communicating with the host. My LG TV and Amazon Firestick both flag low battery before total exhaustion
     
  15. sonic

    sonic Senior Member

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    Up to a year ago I used to get a pack of 2 batteries left in the car after a service.
     
  16. davidsl500

    davidsl500 Senior Member

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    Your Mercedes:
    R172 250CDI, R129 SL500 Gone...
    Ebay is good for 2025's. 10 Varta = £3 delivered
     
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  17. OP
    RichardSEL

    RichardSEL Active Member

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    Regarding other cars, Ive just given back a loaner '07MY Vauxhall Astra (shudder) that had the same form of three button remote fob with a blade. Mech said he'd bought a year ago to give out only as a loaner and not changed batteries.

    I had a Passat 2.0L tFSI '06MY bought in '07 and kept as a daily for 10 years. Changed key fob batteries once. And have had three XJ8 -- all except the last not needing new cells, and that one only the once

    I'd find it strange that this draining battery fault is manufacturer specific. JohnnySBC has replied saying he'd want to "replacement key PCB board". So am assuming he's got the kit there to transfer the coding across. Then just move the passive transponder into the new fob. It'd be worth it if successful...

    ...because it's not Brexit
     
  18. John Laidlaw

    John Laidlaw Senior Member

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    Problem being those batteries only last a few weeks !
     
  19. Rory

    Rory Senior Member

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    Mine had been uncertain to unlock and lock a few times recently so I got some new batteries. They haven't been changed for some years, but I don't use the car much. I was quite surprised that the old ones measured 3V, same as the new ones.

    The fob seems to work fine with the new batteries. So I've no idea what's going on there.

    Random thought for the OP - if bought from eBay etc could be the batteries are fake?
     
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  20. John Laidlaw

    John Laidlaw Senior Member

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    Not tandem at all...it’s not worth the saving just buy decent brands at your supermarket- Varta, Panasonic, Duracell etc
     

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