I was just looking at some coffee pots at work thinking "It would be nice to know how old the coffee is."
And then I went into problem solving mode. Practicality be damned! I went through a few ideas, and came up with what I think is most feasible.
What I envision is a very simple "good/bad" indicator light for the coffee pot. It is based on the temperature of the coffee (or other liquid) in the pot. If the temperature falls below a certain level, the indicator goes from "good" to "bad"
Obviously, you would need to find a good point where good coffee goes bad. You can do this manually or automatically. For example, take the temperature of a coffee pot after sitting for 4 hours and after some general use.
The amount of coffee left would affect the temperature, so you could take temperatures with a full pot, 3/4 full pot, 1/2 full pot, and 1/4 full pot. If the pot is below an acceptable level, you could make it automatically trip the indicator.
You could rig a data logger to note the temperature and liquid level over time to help with the calibration.
I do love brainstorming solutions to a problem. The exercise is good, even if it doesn't produce useful results.
Feel free to add comments and discussion! I welcome feedback of all kinds, as long as it's civil :-)