I realize that when one buys a box of surplus electronic components as a "grab bag" for 8 dollars, one can expect that perishable components such as electrolytic capacitors may not be in "factory fresh condition." That's the price you pay for getting a couple hundred capacitors that may cost .50 to 1.00 (USD) each for substantially less. (depending on what else is in the box for 8.00) Keep in mind all were unused, but "shelf time" was unknown.
I sorted the electrolytic capacitors out, and separated them into values. Some were easy to throw into the scrap bin - their ESRs were greater than 40 ohms, or they were made by some dodgy company, their capaitance measured much less than the nominal, or in many cases, a combination of these conditions.
Some were easy to keep. ESRs were similar to brand new capacitors I have ordered recently from Digi-Key, and capacitance values were within the correct percentage of nominal.
Difficult were those that were "in between." They weren't bad enough to immediately discard, but their ESRs were about double those of my new capacitors.
I decided that I would discard any group that had a large variation in ESR - my theory was they were all very old, if some were drying, the rest would soon enough.
I went back and forth about the consistent batches. Were they in good condition with a higher ESR? (Not as good as that of my new capacitors, even when new?) Were they consistently drying? I finally decided to throw them away, as I figured I shouldn't keep in my stock components that would only get worse with storage, and it would be foolish to store bags of "almost good" components. For what purpose would I use these? I wouldn't want to take a device apart, find a bad capacitor, and replace it with a marginal one. I wouldn't want to put one of these in a new design, and add yet another factor to consider when I throw the switch and it doesn't work.
Do any of you other component scavengers have any opinions/thoughts about this?
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