Editing Capacitor plague (section)

===Electrical symptoms===
The electrical characteristics of a failed electrolytic capacitor with an open vent are the following:
*capacitance value decreases to below the rated value
*ESR increases to very high values.

Electrolytic capacitors with an open vent are in the process of drying out, regardless of whether they have good or bad electrolyte. They always show low capacitance values and very high ohmic ESR values. Dry e-caps are therefore electrically useless.

E-caps can fail without any visible symptoms. Since the electrical characteristics of electrolytic capacitors are the reason for their use, these parameters must be tested with instruments to definitively decide if the devices have failed. But even if the electrical parameters are out of their specifications, the assignment of failure to the electrolyte problem is not a certainty.

Non-solid aluminium electrolytic capacitors without visible symptoms, which have improperly formulated electrolyte, typically show two electrical symptoms:
*relatively high and fluctuating [[Leakage (electronics)|leakage current]]<ref>The Aluminium Electrolytic Condenser, H. 0. Siegmund, Bell System Technical Journal, v8, 1. January 1229, pp.&nbsp;41–63</ref><ref>A. Güntherschulze, H. Betz, Elektrolytkondensatoren, Verlag Herbert Cram, Berlin, 2. Auflage 1952</ref>
*increased capacitance value, up to twice the rated value, which fluctuates after heating and cooling of the capacitor body