2001-2002 Yamaha 50HP F50Z/T50Z Ouboard 4-stroke engines service manual, Page 347Get this manual
Electrical systems
Troubleshooting
Before troubleshooting the charging system, check that all electrical connections are tight and free from corrosion, and that the battery is fully charged to 12 VSymptom: Battery becomes weaker quickly Check the charging system
Measure the output peak voltage of the lighting coil