Re: Samxon capacitor quality discussion (spin-off from OCZ Bug Zapper thread)
Sounds like the aluminum oxide film has been corroded by the highly water base electrolyte, potentially causing a partial short in the dielectric and high leakage current. Things might have changed if they were actually used and kept cool with the ripple current low, over the course of many years, but KZGs that old might just be doomed to failure.
NCC states in the datasheet that if capacitance is within 25% of the nominal capacity after the endurance test, it's still good. 0.040 ohms is a tad high, but if the contact resistance at the leads is an issue, it might not be cause for concern.
The KZG sheet says that it uses the same "advanced electrolyte technology" as KZE. The difference must be in the concentration of ions, or the amount of water, or how conductive the electrolyte is.
Never soldered or had bias applied, but these are a "cut lead" lot. A failed 1500uF measures with C of about 2500uF and anomalous high leakage current - the tester claims that is a cell (i.e. battery) in one direction and diode with Vf=274 mV in another (typical for thinned or non-existent oxide - it probably shares some characteristics of metal-semiconductor diodes).
A good (non-bulged) 1500uF/6.3 measures as 1805uF/40 mohm and Vloss of 1.8%. Slightly high, but still almost within the 20% spec for capacitance after 12 years, so it's not too bad.
Clearly, they missed something in the formula for KZG versus KZE. It should have been easy to fix, unless the two electrolyte formulations are vastly different in their electrochemical reactions, which seems unlikely.
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