I've had the battery on my car for 11 years and now it has finaly given up the ghost.
I was told a few years ago that a battery should be changed every 5 years.
With them getting better, what are your thoughts on this?

They are getting better but electrical loads on them are getting far greater too.

I certainly only change them when they 'die' - and have had many that are a decade old at least. I bet it's battery manufacturers advising to change them more frequently.

I generally find fitting a large stereo system is the acid test - see how they cope with a 40 amp load without the engine running! I had a 'micra' battery in my 200sx because the FMIC pipework fouled the battery tray. That system could play for all of 10 minutes before the engine would fail to crank!

I have the original 9 year old battery fitted to my Mondeo, and it's never been anything other than faultless.

I had a feeling mine was on the way out,as the turn over was sounding like a diesel (perish the thought).
But as I'd left the car on the driveway for 5 weeks and the alarm was trying to tell me something.
The amount of plastic I had to take off before getting a the damn thing was stupid....bloody modern cars eh!

I'm sure a lot depends on the vehicle. I'm lucky if I get 2 years out of a battery on myblackbird but I had one last 15 years in a 928.

I had a relative who used to boast about the longevity of his MK2 Escort's battery. Must have got to about 15 years, if he wasn't lying.

Winter usually finishes off tired old batteries.