Well, pretty much. The capacitor charges exponentially through a series resistor toward the applied voltage, theoretically *never* actually reaching the applied voltage. The use of five time constants to represent "fully charged" is just for convenience. The difference in capacitor voltage after ten time constants, versus the voltage after five time constants, is very small and can usually be ignored in practical circuit design.

There is no such thing as a "full charge" on a capacitor. Barring electrical breakdown, a capacitor can be charged to any voltage and the charge on it will be Q = CV. The method of "charging" the capacitor will affect how the voltage across the capacitor terminals changes. Charging through a fixed resistor from a constant voltage source is just one method, the description of which gives rise to the concept of time constant and exponential time functions.

In practice, there is always *some* parallel leakage resistance, Rleak, across the capacitor. This leakage path forms a voltage divider with the R in series with the capacitor. Therefore, if V is the charging voltage applied to capacitor C through resistor R, the final voltage will be V * (Rleak)/(Rleak+R). If Rleak is MUCH greater than R, the fraction approaches unity so the "final" voltage on the capacitor approaches V. Note that leakage resistance does modify the exponential increase and, because of the leakage resistance, all capacitors charged from a constant voltage source through a resistor **will** reach a constant steady-state voltage eventually, not just theoretically, in a finite amount of time.

Adam could modify his simulation to show the effect of leakage resistance, which often occurs as a result of trying to use the voltage across the capacitor to drive another circuit, say, an analog-to-digital converter or a voltage comparator. This is what happens with the ubiquitous 555 timer where internal leakage limits the maximum value of R that can be used for timing. The maximum value of C that can be used with the 555 is limited by the chips ability to discharge the capacitor when the threshold voltage is reached.