2003 Polaris ATV Trail Boss 330 Factory Service Manual, Page 195Get this manual
ELECTRICAL
CHARGING SYSTEM TESTING
Whenever charging system problems are suspected, proceed with the following system checks: Using multitester set on D.Cvolts, measure the battery open circuit voltage (See Page 10.15)It should be 12.4 volts or moreIs it? Yes
Remove the battery and properly serviceReinstall the fully charged battery or fully charged shop battery
Meter Setting: DC Volts
With the transmission in neutral, start the engine and increase RPM to between 3000 and 4000Read battery voltage with the multitesterReadings should be between 13.0 and 14.6 D.CAre they? No
Check Key off Current Draw Refer to Page 10.13
Meter Setting: DC Amps
Perform system "Break Even Amperage" test outlined on Page 10.13Does charging occur as specified? No