A system for reducing an alternator's load on an engine when the engine drives a second load. The system includes an alternator, a battery, a resistor, and a switch. The alternator includes a stator, a voltage regulator, a rectifier, and a field coil. The battery has a first terminal coupled to the alternator and a second terminal coupled to the alternator. The resistor has a first lead coupled to the first terminal and a second lead coupled to the field coil. The switch is coupled in parallel across the resistor, and is open when the engine drives the second load and closed when the engine is not driving the second load.