Good grief, he's right. I have a dusty bin of assorted lytics,
guaranteed not used for years, some not for decades. Six various caps
measure, in millivolts,
14
180
135
11
22
350
all in the "plus" direction.
I shorted that last one, the 350 mV guy, for 5 seconds. It dropped to
2 mV but is steadily charging itself back up, 10 mV now after a couple
of minutes.
That makes sense: aluminum plates of various purity and oxidation
level, some sorts of leadwires, all glopped with sulfuric acid and
additives.
Cool.
John
More:
Surface-mount MnO2 tantalums, right off the reel, initial charge in
mV:
300 33 uF 25v
730
820
1.2
150 47 uF 25v
70
4
I shorted the 820 mv guy for about 10 seconds and it went to 2 mv but
started recharging, to about 35 mv so far. Unloaded, it charges, but a
10M load pulls it back down.
A bunch of never-used polymer aluminum caps, United Chem-Com 100u/16v,
had initial voltages from 200 to 500 uv. I shorted one, and it went to
a few microvolts but is charging back up.
I suppose I could measure the short-circuit currents too.
So, avoid lytics in dc-sensitive circuits!
John