Capacitor Lifespan

[KingKrak]

Hey,
I was wondering if anyone knew a little about the capacitor lifepspan's that are shown on manufacturer's datasheets.

I have been looking at quite a few datasheets lately and the lifespans are generally listed to be around 1000 to 3000 hours. There are about 8500 hours in a year.

So many electronics run for so much longer than this (for example, my 5 year old computer which has run 24 hours a day from when I bought it). So what am I missing here? Is that number rated at a high temperature or something?

Thanks

 

[Speakerguy]

Yes, they are typically 2000 hours or so at 85C. Some better, some worse. At room temperature they will last a few decades.

 

[Nigel Goodwin]

Always buy good quality electrolytics, and only 105 degree ones - the main cause of failure over the last couple of decades is high ESR electrolytics, with poorly specified ones barely lasting 12 months.

 

[Hero999]

The rating also includes ESR and reduced capacitance.

If the device is designed to work with a 20% higher ESR than the rating and a capacitance of 64% of the value, it should last for much longer.