1997 Johnson Evinrude "EU" 90 thru 115 90 CV Service Manual, P/N 507267, Page 238Get this manual
Description of Charging System The outboard charging system consists of battery, flywheel, an alternator stator, and, rectifierregulator which provides full wave regulation of the systemThe engine's battery can affect the charging system operationThe battery should be of heavy-duty marine construction, should be the correct capacity for the application, and should be in good condition with normal charge
The engine's flywheel contains the permanently charged magnets which provide the energy to power the stator windingsThe magnets must be at their original design strength for full alternator outputl]]
The alternator stator consists of many windings of wire wrapped around metal laminationsThe stator is attached to the upper crankcase headThe flywheel's magnetic lines of force cutting through the stator windings produce alternating currentThe stator or its leads could be damaged, which could result in reduced or no alternator outputThe rectifier on non-regulated models consists of series of diodes, built into metal case, which changes the stator's alternating current to the direct current used to charge the batteryOne, several, or all of the rectifier diodes might become damaged, resulting in system grounded condition, no charge condition, or an incorrect charging rateThe rectifierregulator on regulated 6-amp and 9-amp models performs the above functions and provides full wave regula tion of the charging systemAn additional circuit, represented by the gray lead, provides tachometer signal for the CIVIC Quartach and 7K tachometers