1995 Johnson/Evinrude Outboards 9.9, 15 four-stroke Service Manual, Page 202Get this manual
RectifierRegulator Tests Variable Load Tests To test the operation of the rectifierregulator, you must be able to run the engine continuously at approximately 3000 RPM, 6-amp system, or 5000 RPM, 12-amp systemThe test consists of monitoring the system's response to partially discharged batteryTwo methods for performing this test are described belowVariable Load High Rate Discharge Method
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rectifierregulator requires battery voltage from the purple lead to operateBefore proceeding, separate the rectifier regulator purple lead bullet connectorVerify battery voltage at the engine harness connector when the key is ONReconnect the purple lead bullet connector1Disconnect battery cables
2Connect 0-40 amp ammeter in series between the rectifierregulator red lead and the battery side of the starter solenoid3Reconnect the engine's battery cables
Following the manufacturer's directions, connect the variable load tester (carbon pile) across the battery terminalsSteven's Instrument Model NoLB-85 and Snap-on Model NoMT540D are examples of testers availableExcessive battery discharge rates might overheat battery causing electrolyte gassingThis might create an explosive atmosphere