The battery (CR2032 3v) in my smart key only lasts a month or so. I have a TDV6 HSE, 2010. Previously I had a 2008 HST, no smart key. As I am new to the smart key can anyone advise on what an average life for the battery should be. The car get used daily. I have to say I preferred the old key in a hole approach, mind you its a small niggle in an otherwise great car.

My smart key battery has not needed replacing and I do not get any battery warnings, i.e. "SMART KEY BATTERY LOW" displayed in the message centre.

I have done 14,000 miles over 24 months. I'd be interested to know when others have found their batteries expire. But once a month must surely relate to an issue or a bad batch of batteries? L405 P400e Autobiography (MY2020)... Silicon Silver / Espresso
RRS TDV6 HSE Lux (MY2011)... Nara Bronze / Arabica - now gone!

Got to be something wrong! Batteries are usually changed during annual service, come as part of service pack. You not sitting on keys or dropped in a puddle recently? Maybe off beam as not sure what functions or buttons are on smart key. 2x TDV6. SE and HSE. Both returned to sender with issues👀
TDV8 Sport HSE...... Gone. Loved it but it didn't love me!!
Now rolling in MY10 Fullfat TDV8 Vogue. Slammed it to go round corners🙈
Cruising daily #56 mph in a Volvo V8. 😱
Lots of other toys in the cupboard...😜

Thanks for the comments. I figured there must be something wrong somewhere as a battery a month does seem a bit harsh. I think I will give the other key a go to see if it lasts longer. I have also bought some new batteries and thrown away the ones I had to see if that helps.

Somehow on the 2010, the car knows or is timed at 24 months, as mine started giving me warnings that battery was low each time I got in the car, even using the spare which rarely gets used.
I'd say you have a problem, possibly even with the dash giving out duff info - like mine now saying i have no fuel left, despite a full tank! Sounds like it will be warranty job
Cheers
Dave MY10 TDV6 SE (debadged ), Santorini Black, Flappy paddles, Privacy Glass, 20" Stormers, Mudflaps!

Gone: a comprehensive list of imprezas and a Merc ML AMG

Thanks Dave. Mine only has 7300 on the clock. Just got it a few months ago, lucky to find a 2010 car with low mileage.

Hmmm....my 14 month old MY12 has started doing showing the warning this week

Edit: Ah, easy fic, new CR2032 battery in, jobs a good'un  ON THE WAY: BMW F21 M140i
MERCEDES GL350 - Metallic Navy Blue w/Grey interior

GOING: BMW F31 335D MSport+ xDrive Touring
GONE: Land Rover Discovery 4 HSE - Stornaway Grey w/Black Interior (wish we'd kept it )
GONE: BMW F10 520D MSport - Carbon Black
GONE:MY12 RRS SDV6 HSE Sumatra/Ivory/Grand Black Privacy glass

BC, did you replace battery in both fobs? I had to in mine the spare one is only used occasionally but still came up with the warning, which makes me think the warning comes from the car, not the state of the battery
Cheers
Dave MY10 TDV6 SE (debadged ), Santorini Black, Flappy paddles, Privacy Glass, 20" Stormers, Mudflaps!

Gone: a comprehensive list of imprezas and a Merc ML AMG

Not tried the other fob, I'll.check that today and revert back  ON THE WAY: BMW F21 M140i
MERCEDES GL350 - Metallic Navy Blue w/Grey interior

GOING: BMW F31 335D MSport+ xDrive Touring
GONE: Land Rover Discovery 4 HSE - Stornaway Grey w/Black Interior (wish we'd kept it )
GONE: BMW F10 520D MSport - Carbon Black
GONE:MY12 RRS SDV6 HSE Sumatra/Ivory/Grand Black Privacy glass

The new batteries seem to have sorted things for me.

Checked the other set of keys and all good, so seems not to be a 'time' thing.  ON THE WAY: BMW F21 M140i
MERCEDES GL350 - Metallic Navy Blue w/Grey interior

GOING: BMW F31 335D MSport+ xDrive Touring
GONE: Land Rover Discovery 4 HSE - Stornaway Grey w/Black Interior (wish we'd kept it )
GONE: BMW F10 520D MSport - Carbon Black
GONE:MY12 RRS SDV6 HSE Sumatra/Ivory/Grand Black Privacy glass

36 months and 20,000 miles... both smart keys now cause the following to be displayed "SMART KEY BATTERY LOW". Ordered a few Duracels off ebay, very cheap, £2.80 for 5!!

http://www.ebay.co.uk/itm/221215559318 L405 P400e Autobiography (MY2020)... Silicon Silver / Espresso
RRS TDV6 HSE Lux (MY2011)... Nara Bronze / Arabica - now gone!

36 months and 20,000 miles... mine has now displayed "SMART KEY BATTERY LOW". Ordered a few Duracels off ebay, very cheap, £2.80 for 5!!

http://www.ebay.co.uk/itm/221215559318 L405 P400e Autobiography (MY2020)... Silicon Silver / Espresso
RRS TDV6 HSE Lux (MY2011)... Nara Bronze / Arabica - now gone!

I have been told it's part of a service. Every time I've had mine serviced they have changed the batteries in both remotes.  MY11 Autobiography supercharged. Santorini Black. Monaco interior. Rear screens. Privacy.
Gone MY08 Supercharged HST. Java black. Ivory premium interior. Rear screens. Privacy. Missed a lot.
Gone MY04 Discovery V8 Petrol ES Premium. Awesome.