1995 Mariner Mercury Outboards Service Manual 50HP 4-Stroke, Page 41Get this manual
Battery Charging System Troubleshooting
CAUTION
The charging system may be damaged by: 1) reversed battery cables, 2) running the engine with battery cables disconnected and stator leads connected to rectifier, and 3) and open circuit, such as broken wire or loose connectionA fault in the battery charging system usually will cause the battery to become underchargedCheck battery electrolyte level, and charge batterySee "Electrolyte Level", and "Charging Discharged Battery"If battery will NOT accept satisfactory charge, replace batteryIf battery accepts satisfactory charge, determine the cause of the charging system problem as follows1Check for correct battery polarity [RED cable to POSITIVE (+) battery terminalIf polarity was incorrect, check for damaged rectifierSee "RECTIFIER TEST"2Check for loose or corroded battery connections 3Visually inspect wiring between stator and battery for cuts, chafing; and disconnected, loose or corroded connection 4Excessive electrical load (from too many accessories) will cause battery to run downIf visual inspection determines that battery connections and wiring are OK, perform the following stator and rectifier tests