1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 352Get this manual
Alternator Circuit Troubleshooting65 Tiller and Remote Electric Start, 100 Manual Tilt Models
Undercharged Battery Check condition of batterySee paragraph Battery at the beginning of this sectionCheck all connectionsThey must be tight and cleanCheck electrical load on systemTotal current draw from engine and accessories cannot be greater than what is listed belowExcessive draw will discharge battery-=I
Models 65 and 100 Manual Tilt
Maximum Current Draw Amps
Starter Solenoid To Accessories Ammeter Battery
Alternator Output Check Disconnect the red lead from rectifier to red lead on terminal block No4Connect to 15 amp ammeter between the two leadsConnect the red lead from the rectifier to the "S" side of the ammeter and the other red lead to the "I" side of the ammeterStart and run engine in its full throttle operating rangeAt this speed, the ammeter should indicate the rated output of the alternator as specifiedI no charge is indicated, test the alternator stator and the rectifier