Alternator testing properly

CORE TEACHING Alternator output; rectification; B+ path; ground; charge at idle/load; voltage drop; belt/mechanical checks; ripple concept. Add alternator three-phase generation: rotor magnetic field, three stator windings, AC generation, six-diode rectifier, DC B+ output, diode faults and why ripple appears. PRACTICAL DEMONSTRATIONS AND TESTS Resting voltage; running voltage; headlights/blower/heated screen load; alternator B+ to battery positive drop; case-to-negative drop; current clamp. Scope alternator ripple if equipment allows; show how a failed diode/phase changes the pattern. ADVANCED / SCAN TOOL LAYER Scope AC ripple / diode pattern as an advanced section; scan generator command/load PID if available. KEY DIAGNOSTIC QUESTIONS Is the alternator generating? Is output reaching the battery? Is the ground path good? Is output adequate under load? MUST-COVER CHECKPOINTS Battery baseline; generator command if smart; output at alternator; output at battery; loaded test; cable drops; current; three-phase/diodes; ripple.

Battery keeps going flat but the alternator shows 14.2 V. Is the charging system definitely good?

Builds on

Lesson 8: Starter relay and start-control circuits

Feeds into

Lesson 10: Smart alternators and battery monitoring

1. 07Complete starter motor diagnosis
2. 08Starter relay and start-control circuits
3. 09Alternator testing properly
4. 10Smart alternators and battery monitoring
5. 11Battery-going-flat diagnosis