2003 Polaris Scrambler 50-90 Sportsman 90 Predator 90 Service Manual, Page 92Get this manual
ELECTRICAL
CHARGING SYSTEM TESTING
Whenever charging system problems are suspected, proceed with the following system checkUsing multitester set on D.Cvolts, measure the battery open circuit voltage (See Page 5.5)It should be 12.5 volts or moreIs it? Yes
Meter Setting: DC Volts
Remove the battery and properly serviceReinstall the fully charged battery or fully charged shop battery
With the drive wheels securely off the ground, start the engine and increase RPM to between 3000 and 4000Read battery voltage with the multitesterReadings should increase to between 13.0 and 14.6 D.CAre they? No
Meter Setting: DC Amps
Check Key off Current Draw Should between .1 and .2 volts
Perform system "Break Even Amperage" test outlined on Page 5.9Does charging occur as specified? No Ohm stator wire (WYR) If bad replace, if good, continue with alternator output testMeter Setting: AC Amps