STARTING & CHARGING SYSTEM DIAGNOSIS Battery Starter Alternator

Test Equipment VAT–40 & AVR Voltmeter Ammeter Carbon-pile variable resistor

Safety Issues Batteries can explode if sparks occur around them. Battery acid is very corrosive. It can burn skin and cause blindness. Remove negative battery cable if making any large repairs.

Battery Identification Conventional Lead Acid (Cap Battery or Deep Cycle) Maintenance Free AGM (Absorbed Glass Mat)

Battery Testing Battery capacity or load test. Battery drain test. Hydrometer test. (Cap batteries only) Special Testing for AGM Batteries (Absorbed Glass Mat)

Battery Load Test Discharge battery ½ cold cranking amps. Battery + - ammeter voltmeter Carbon pile >9.6v ½ CCA Turn resistor to get amperage (artificial load)

On the Car Connections

Battery Services Clean battery case Clean battery terminals Check proper hold down Charging batteries Jump starting Replacing batteries

Cleaning Batteries

Battery Charging Standard Slow Charger Fleet Battery Charger 2 – 12 amp capacity. Fleet Battery Charger high amps can jump and fast charge.

Jumping or Boosting a Dead Battery Positive to Positive Negative to Ground

Starting System Testing Starter load or draw test. Starter voltage drop. Cable voltage drop. Solenoid voltage drop.

Starter Draw Test ammeter voltmeter Measure while cranking engine Note: ammeter in series and voltmeter in parallel.

On the car connections

Battery Cable Test (Voltage drop) voltmeter 0.5v max. voltmeter Measure while cranking engine 0.2v max. Note: Voltmeters to be set at low volt scale.

Testing the Solenoid (voltage drop) Measure while cranking engine. voltmeter 0.2v max.

Starter Bench Test

Installing a New Starter Safety tip: Always remove negative battery terminal.

Alternator/Regulator Testing Alternator output test. Voltage regulator setting. Full field test.

Alternator Output (amps) Run engine at 1500 –2000 rpm. Battery To vehicle load amps - + Read output here. Carbon pile Amp rating on alternator Alternator Adjust to max. alternator output (artificial load)

On the Car Connections

Voltage Regulator Setting Run engine at 1500 –2000 rpm. Battery To vehicle load - + 13.8 - 15.3v Voltmeter Carbon pile Alternator Quickly load alternator and back off.

Full Field an Alternator When you have a dead charging system use this test to determine if the alternator is at fault or the regulator is at fault. The test basically puts full battery voltage to the field winding in the rotor of the alternator. If the alternator is OK it will put out maximum output and the regulator is the problem. If no output is still noticed the alternator is faulty.

Full Fielding This will build a large magnetic field in the field coil.

Diode Scope Pattern