. A red wire with a diode and black wire without a diode is a Dual Circuit system that offers a red wire DC for battery charging and the black AC wire is positive to power the lights
The red wire typically carries this AC voltage to the diode, which allows current to flow in only one direction (rectifying the current). The output from the diode (now DC) is then routed to a voltage regulator (or rectifier/regulator) that ensures a stable voltage output to charge the battery and power the electrical components of the mower.
