Key battery

[garethdeb]

Hi folks
My spare key works fine in the ignition but does nothing on the lock and unlock buttons so I'm banking on a dead battery. I've taken it for a drive with the spare but didn't charge so I did a search on here for how to replace it. Found the link to the yank site with a Pretty good description of how to change it but I just wondered if anyone on here had tried it themselves? At £150 for a new key I don't really want to be mashing it up!
Cheers all
Regards
Gareth



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[PhilT]

Yeah, I replaced mine last year. Straight forward enough job. Once you've replaced it I'd suggest using that key for a while to charge it up, but take your spare with you until the new battery has got a good charge in it - just in case!

[garethdeb]

Thanks Phil. Where did u get the battery from? Did u follow the same guide I found?
Regards
Gareth



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[PhilT]

Will find the link and post you some more info when I get in tonight

[PhilT]

Here you go mate:

'How to' link
http://www.xoutpost.com/bmw-sav-forums/ ... y-fob.html

Ebay link for battery
http://www.ebay.co.uk/itm/VL2020-BMW-BA ... 4cfb910b97

When you slice the key open be careful not to let the stanley blade go too far in or you may catch the internals (as well as being careful not to slice your fingers etc. ). Also, the guide says to solder the battery back in place but mine seemed to be held quite firmly so I didn't bother with the solder and its been fine.

[garethdeb]

Ok, ordered the battery so I'll be giving it a go hopefully this week. Stupid question but will the new battery have charge in it to be able to program it or will I have to charge it for a few miles first?
Cheers guys
Gareth



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[X5Sport]

Most batteries come at least part charged, but you will in all likelihood need to give it a run to get more charge in there. It will depend upon how long the battery has been on the shelf, and it's type (NiMH, NiCd, Lion etc).

[PhilT]

I had to hold the key close to the rearview mirror to get it to program (which apparently is where the receiver is) so I'm guessing there wasn't that much charge in the new battery.

Also, I've been told that the battery charges up using some sort of proximity sensor, it doesn't actually have to be in the ignition, just near it (dunno how true this is but it came from a BMW mechanic).

[X5Sport]

There's an inductive charging ring (coil of wire) around the ignition key slot which provides the necessary energy. Same system some electric toothbrushes now use.

Indeed there is anecdotal comment on the web that the Braun 'Sonicare' chargers could recharge a BMW key. Whether truth or myth I have no idea.

[garethdeb]

Don't think I'll try that one, guaranteed to fry the new battery knowing my luck!
Gareth



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