Mercury Mariner 25HP 4-Stroke Outboard Service Manual 1997, Page 79Get this manual
Alternator System Test (15 Ampere Stator) 1Check battery voltage at battery with engine running
10If ammeter reads less than required amperes 5000 RPMtest the stator; refer to "Stator Ohm Test "If stator tests OK, replace rectifierreg ulator
2If battery voltage is above 14.5-15.0 volts, replace voltage regulatorrectifierCheck condition
of battery as overcharging may have damaged
battery3If battery voltage is below 14.5 volts, charge batteryreferto "CHARGING DISCHARGED BATTERY"If battery can NOT be satisfactorily charged, replace battery
Stator Ohms Test
STATOR (BATTERY CHARGE COIL)
4If battery accepts sati sfactory charge, check battery voltage while cranking engine; refer to "CHARGING DISCHARGED BATTERY"If
cranking voltage is not acceptable, replace battery5If cranking voltage is acceptabledisconnect the