Since the starter motor is relatively small, it needs a continuous source of very high current just to be able to produce the energy needed to start a cold engine. Making this happen is the starter solenoid. The starter solenoid is basically a large electronic switch that can handle the hundred of amps of electricity delivered to the starter motor by the battery. As you turn the ignition switch of your Jeep to the start position, the starter solenoid gets activated, thus connecting the starter motor to the vehicles battery.
The starter motor has to overcome a lot of forces just for the engine to start running. Among those forces are: the internal friction in the piston rings; the compression pressure in the cylinders; the energy needed to open and close the valves; and the energy needed to move every other component directly attached to the engine, including the alternator, water pump, oil pump and others. With all of these forces to overcome, it will make you wonder where the small Jeep starter motor gets all the power it gives off.