The current is at its maximum when the time approaches infinity. The current is at its minimum when the time approaches 0. At some point between these two extremes, there will be an area where the current has a fixed value that does not depend on small changes in t. This happens for instance near t = 20s and 12i0=12- i00 . The location of this area depends on how much power is delivered to the circuit – if more power (larger values of P) are delivered then it will happen sooner; if less power is delivered then it will happen later or not at all. In fact, with no external load resistance R connected to the terminals A and B, one would see such a voltage divider effect as seen in figure below: Figure: Voltage Divider The voltage across the load resistor R is Ri0=12- i00. The current in this case would be 12i0, since there is no path for electrons to flow from terminal B back to A when there’s a zero volts difference on both terminals. If you were to increase the power delivered by increasing P (but still not connect an external load resistance), then more power will go into heat dissipation and less into generating current – at some point it will cross over to become greater than 0 and remain that way until infinity! If you set up your own experiment with ammeter & volt meter or multimeter connected as shown below: Figure: Ammeter & Voltm