On Fri, 2008-12-26 at 21:00 -0500, gene wrote: > What does it mean when manufactures specify 'Endurance @ temp' or 'life > time @ temp'? For example, one company claims: > Endurance : 105 C 1000 h to 5000h > Then they further state that after testing at 105C with maximum ripple > current applied, that when the part is cooled to 20C, it will then meet > original specs.
It will still have had its life-time shortened. The spec you quote above, AIUI, means that after somewhere between 1000 and 5000 hours of operation at 105 degrees centigrade, the cap (as measured at 20 degrees) will be outside of its quoted specifications. I can't remember the exact numbers, but derating to lower temperatures has a stupid factor of lifetime increase. It might even be as much as double the life-time for every 10 degrees drop in working temperature. I guess that merely being at elevated temperature is also lifetime degrading. You circuit wouldn't need to be on for the electrolyte to be degrading. -- Peter Clifton Electrical Engineering Division, Engineering Department, University of Cambridge, 9, JJ Thomson Avenue, Cambridge CB3 0FA Tel: +44 (0)7729 980173 - (No signal in the lab!) _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user