I have researched about capacitor charging time, with its charge being at 63% after 1 time constant, being t = RC. I am trying to repeat this by myself, using a 16V 1000µF capacitor, a 1KΩ resistor, and a constant power supply (~7.3 volts, ~1.9 milliamps) from a solar panel, which, as I understand capacitor charging (I may be totally wrong about this, if so please correct me) one time constant should be equal to t = RC = (1KΩ)(1000µF)= 1 second.
Theoretically, after 1 second, the capacitor should be at 63% of its capacity. For it to be at 99% of its capacity, 5 time constants must pass by. I tried this, and I waited for 5 seconds, disconnected the capacitor from the solar panel and resistor, and using a multimeter measured the capacitor's voltage, which didn't even reach 1.5 volts at any of the many times I tried.
I don't understand it, is it that the way I am trying to find the charging time is wrong, as a consequence of informing myself totally wrongly, or that the capacitor that I am using is defective?