Alternator, Check
The check consists of a power check and a regulated voltage check - the power check must be performed first. Use a suitable oscilloscope to check the electronic components at the same time.
The test can be carried out both in the installed state and on the test bench. The test is described below for the installed state, the test on the test bench is performed analogously.
A charged battery is necessary for the test.
Note following safety measures:
- Negative terminal from battery, alternator and regulator must correspond.
- Never allow the alternator to run in an uncontrolled open circuit.
- Never short circuit the terminals to alternator and regulator.
- Never reverse polarity of alternator.
- For connection to an additional battery (e.g. starting aid) ensure that the same battery terminals are connected to one another.
- When charging the battery pay attention to polarity of the connection terminals of the charger. During the charging operation in the installed state, the ground lead must be disconnected.
Alternator Power, Check:
Circuit diagram:
- Load resistor connected in parallel to the battery
- Battery,
- Voltmeter,
- Ammeter
- Ignition lock
- Battery charge telltales
- Alternator
Disconnect battery, disconnect connecting cable from the alternator terminal "B+". Connect ammeter (measuring range 100 A) into disconnected line.
Connect adjustable load resistor to battery terminals. Set resistance before the connection to "0". First connect to battery, then to resistor. Connect rpm gauge. Connect oscilloscope in accordance with manufacturer's instructions. Connect battery.
Start motor and read off generated current at different rpm.
Alternator Power, Check:
Adjust load resistance if the required load currents are not achieved. The shape of the voltage curves on the oscilloscope should be uniform. Test value: 5 to 7 A.
If the required minimum current intensities are not achieved or if the oscilloscope indicates deviations, then the alternator must be overhauled.
Regulated voltage: circuit diagram
- Battery,
- Ignition lock
- Battery charge telltales
- Resistor connected in series to the battery to achieve the load current
- Voltmeter,
- Ammeter
- Alternator
Check regulated voltage: connect rpm gauge, voltmeter /ammeter and load resistor according to manufacturer's instructions.
Disconnect battery. Disconnect cable from alternator terminal "B+". Connect ammeter (measuring range 100 A) between disconnected cable and alternator terminal "B+". Connect resistor in series to battery.
Start motor. Adjust load resistance until the ammeter indicates the prescribed value. Read off regulated voltage - for test values see "Technical Data".
Check alternator only with parallel-connected, fully charged battery, only switch off load resistor and battery once the alternator is at a standstill.
Switching off load with battery not connected in parallel generates voltage peaks which may lead to the destruction of the alternator diodes.