I've recently been hired in a lab at my university to continue research on supercapacitors, specifically leakage resistance. The former student who set up the current tests was a chemist so the professor wants me to verify all of the testing procedures.
In my research about measuring capacitor leakage, manufacturers of electrometers (or other high input impedance devices) say that you must supply the capacitor with a constant voltage to measure Rleak and it will subsequently decay over time. My question is why should a constant voltage be applied and why would this make Rleak decay? Wouldn't it be constant? It seems like a better test to me would to fully charge the cap, then disconnect the power supply and measure how much current is then leaking as a function of time.
Any thoughts on this?