How often do you change key fob battery?

[celica]

It feels like I'm forever changing mine, which is every few months

Could it be affected by car battery, what could be draining key fob?

[Graeme]

I've had mine 7 years 3 months and never changed key fob batteries - in fact I don't know how to open them! I cannot recollect seeing anything in the manual about this either.  Advice given to me when I bought the car was to alternate the key fobs periodically because they charge up in use.  In theory two people can each have a key with different seat and wheel settings and that can lead to irritation if keys are alternated and the seat and wheel moves each time!  I'm the only one that drives my car so it doesn't matter to me, but...

It sounds as though there must be a fault if yours are discharging - and if both discharge then I'd suspect it's the feed from the car to the key.

Not much help, sorry to say

Graeme

[celica]

Thanks

Feed from car is interesting thought , as I keep having battery issues with the car where the clocks resets
Will ask the garage when I get a fault code reading later

[celica]

Also as FYI

On the key fob back there is a button where you press and pull out a physical key
You'll then see a flap which can be pulled opened to reveal the battery

[Graeme]

Thanks for the info about the key.

About 6 years ago I was having the same problems as you - clock and radio settings "disappearing".  The car was under warranty and charge/discharge was checked a couple of times because the read-out from the key about the length of journeys didn't show anything untoward.  However, the clock problem surfaced again after about 3 or 4 short journeys.  Eventually the dealer identified the wrong battery (too small)  had been fitted at manufacture (it's a 3.0d, 7 seater).  They had to source a new one from Germany, fit and recode it.  Until last year it was fine, then it wouldn't start after being serviced in November (doors open for an hour or so, start and stop a few times and key in to hold it in neutral) - so it looks like the 6 yr old battery is on its way out. 

More anon!

[squeaky2]

Cars with comfort access have a battery in the keyfob.  I think the rest are supposed to charge when in the slot

[celica]

Old battery was 90ah

I think the new one is 100ah so has a bit more power to old one

[X5Sport]

If you have a 100Ah key battery you would need a trolley to carry it......

It's the rechargeable button cell in the key fob that was referred too.  They are mAh rated - 20-30mAh typically but BMW may have a special variant.

[celica]

Whoops I meant my car battery is 95a

I'll check the key fob battery
It's a generic Duracell one

[celica]

Doesn't say what mAh

[X5Sport]

CR2032 series.  Non rechargeable - comfort access doesn't use rechargeables.  I have the same in my Skoda and the book says expect every 6-9 months in 'normal use' which I read as twice a day?  I don't expect the BMW one will be much different.  Might even come from the same German supplier!

You can get these batteries really cheap from Amazon.  12 Panasonics for less than £5 and dated to 2020 on my last (Dec 15) order.  Much cheaper than the High St 

[celica]

Good thinking

Will order them in through the net
But doesn't explain why I'm changing every month or two?

[celica]

Panasonic from eBay £3.99 for 12
Is it these you have?

Can't see much difference between panasonic or Duracell

Look at this on eBay:

http://www.ebay.co.uk/ulk/itm/290423351203

12 x Panasonic CR2032 3V Lithium Coin Cell Battery 2032

[X5Sport]

Looks the same to me.  There probably isn't much difference between Panasonic & Duracell really....they're both quality items.

[celica]

Thanks

Still unsure what's drawing the key fob battery though

Although Indy said there's an update for my cache or something which is a module between key and something