I have a Kidde model KN-COB-B battery-powered carbon monoxide detector that I bought in January, 2006. The manual says that the life of the detector is 7 years from first use, and that it will begin generating an alarm beep every 30 minutes when it reaches 7 years of life.
However, I only use the detector during furnace season - about 6 months of the year - and take the batteries out the rest of the year. So I'm wondering if the lifespan is a function of the total time it is actually running, or just the passage of time.
What component in a CO detector would have a limited lifespan? Would such a component's lifespan be a function the total time it is on and running, or just the passage of time whether running or not?
I assume the device itself calculates total time while it is running, so it can't know how much time has actually passed in my case - unless it has a lithium battery built in, or a WWV receiver. No evidence of either.