2006 Johnson SD 30 HP 4 Stroke Outboards Service Manual, PN 5006592, Page 87Get this manual
ELECTRICAL BATTERY CHARGING SYSTEM Disconnect all wires from the fuse caseCheck for continuity between the whitered lead wire with the plate terminal and the other two lead wiresIf there is no continuity, replace the fuse caseWARNING
Excessive battery discharge rates might overheat the battery, causing electrolyte gassing and creating an explosive atmosphere
Start and run the engine at various speedsUse the variable load tester to draw the battery down at rate that is equivalent to the stator's full outputThe ammeter should indicate the following outputs: 10 amps at 700 RPM 15 amps at 1200 RPM 13 amps at 5000 RPM Reduce the battery load toward zero ampsThe ammeter should indicate reduced outputAs the current draw decreases, the battery voltage should stabilize at approximately 14.5 voltsIf the results vary, check the condition of the stator with resistance test before replacing the rectifier and regulator
Checking the Resistance
Rectifier and
Regulator
The rectifier and regulator is solid-state device that cannot be reliably checked with resistance testsInstead, the engine must be run continuously at approximately 3000 RPM in test tank or on marine dynamometer while the system's response to partially discharged battery is monitored