I am testing time constants for a capacitor. Practical implementation is almost accurate as theoretical calculation. But the Time const changes(rises) when I introduce an LED in series with R AND C.

cap=1000uF; Res=10K; Vcc=5V;
When only Cap and resistor is present, the Time constant comes out to be 10sec at 63% of vcc which is ~3v1 and practically it comes out to be ~11sec so it's okay.

But when I introduce 2v2 Red-Led in series with it, the time const **rises** to 30sec. As far as I know, LED has internal resistance in mili-ohms so the R will not be the reason for this **much change**.Other factor is the LED capacitance, It will probably have some value but that value should **reduce** the Time constant instead of increasing it because it is in series with the 1000uF so the overall capacitance should be low, hence (RXC) should be low.

Am I missing something?