I have removed an SMD capacitor out of a circuit and put it in series with a resitor to try to get its capacitance value.

Starting from time constant formula ζ = RC.

So, I used a 10kΩ resistor (real value of 9630Ω) and 5.05V on the power suply.

63% of 5.05V is 3.18V, so on the scope I checked when the capacitor reached this voltage and I got 188ms.

Knowing this I got the C out as C = ζ / R <=> C = 188ms / 9630Ω = 19.52μF.

Ok, so the nearer nominal value is 22μF, so I think ~11% of error was OK.

(did a check by doing the same math but for 22μF value - time constant of 211ms - and compared the error and I also got 11%)

But then, I tried the same exercise but with 12.05V.

I got a time for the 63% of voltage of 0.103ms.

I found it weird because the ζ formula doesn't depend on charging voltage.

And just to make sure I wasn't doing anything wrong I went until the end and got around 10.70μF.

So, shouldn't I get the same time constant regardless the charging voltage? Shouldn't be the charging current the one being different?