The charging system on the Polaris Sportsman consists of the battery, alternator, circuit breaker, and voltage regulator. Alternating current generated by the alternator is rectified to direct current. The voltage regulator maintains the voltage to the battery and additional electrical loads at a constant voltage regardless of variations in engine speed or load. Failure at anyone of these areas can cause the entire charging system to shut down. If you suspect charging system trouble, clean and test the battery before moving on to the system itself.
Check the battery cable connections and the main circuit breaker that is located adjacent to the battery. If the main circuit breaker is good, proceed to the next step.
Test the battery specific gravity using a hydrometer with numbered graduation from 1.100 to 1.300, rather than one with just color-coded bands. Specific gravity is the density of the electrolyte as compared to pure water.
Connect a 0 to 20 DC voltmeter to the battery terminals. Connect an inductive tachometer to the spark plug. Start the engine and increase engine speed to 4,000 rpm. Read the voltage indicated on the voltage meter. it should read between 13 and 14.6 volts.
Check the charging system wiring harness and connectors for dirty or loose-fitting terminals; clean and repair them as required. If the wiring harness and connectors are acceptable and no problem has been found after performing the previous tests, you can consider the regulator/rectifier to be defective by a process of elimination.
