The stator is a winding of wire in a particular pattern on a frame. Magnets located in the flywheel pass by the stator when the engine is running and the stator will put out alternating current usually around 30 VAC. This output comes out of two wires from the stator which are connected to a rectifier/regulator assembly. As part of the AC output is the wrong polarity, the rectifier blocks it. The part of the AC that is the correct polarity is regulated to usually 13.8 to 14.3 volts DC as in direct current with the engine running at half or higher throttle and the battery and electrical system accept this. This is what is called a half wave charging system. Pulsating DC within the regulated voltage range is what this type system puts out and the battery has sufficient capacitance to accept pulsating DC and make it more like a steady flow of DC.
On power equipment that have small engines with half wave charging systems, the key switch has several functions, one, it controls the battery power to the machine, and two, it opens the charging circuit when in the off position. The purpose of opening the charging circuit when the engine is not running is to prevent the stator from motorizing or attempting to crank the engine which will kill the battery very quickly.
A half wave charging system is the most basic of charging systems and lends itself to installation on small engines in addition to being cost effective for this application.
The parts that makeup this type of charging system are, stator, engine flywheel magnets, regulator/rectifier assembly, fuse(s), keyswitch, battery, and of course wiring with connectors.
Mad Mackie in CT