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How to check a motorcycle generator?

When we start the motorcycle, the generator starts to work, namely to generate current.
From the generator, the alternating current goes to the voltage regulator relay, and from the regulator relay, it is converted into constant voltage to charge the battery.
The alternator produces alternating current and the voltage between its windings changes depending on the engine speed, from about 50 to 150 volts AC.

In the meantime, there is no need to worry about it. ”

Initial generator check with a digital multimeter


The check consists of several steps, such as:

- Measuring the resistance of the generator windings. (Check for a break);
- Checking the generator windings for a short to ground;
- Measurement of the voltage produced by the generator.

1. Check the resistance of the generator windings.
The generator has three windings and we check them as follows: take a multimeter (also known as a tester), select the 200 Ohm measurement mode, close the probes together, and zero appears on the display. If so, then the multimeter is ready for work. We check the stator windings. We measure the resistance between the three yellow wires (in the Y-yellow diagram) coming from the generator, disconnecting the block, in the sequence (1 - 2), (1 - 3), (2 - 3). The resistance of all three generator windings should be approximately 1 ohm.
A slight deviation of the readings is allowed, the main thing is that the measurement readings of all three windings are the same.

2. We check the windings for a short circuit with the case.

We turn on the multimeter in the resistance measurement mode of 200 Ohm, attach the black tester probe to the "ground", and with the other we pass through each contact in the connector. There should be no tester readings, i.e. "1" on the indicator. If the tester has any readings other than 1 (one), then most likely you have one or more windings in contact with "ground", which is already a malfunction.

3. Check the voltage supplied by the generator.

This is also a simple test, but it requires compliance with safety measures and accuracy, since you will have to measure a higher voltage from 50 to 150 volts AC and electric shock is not excluded. And also when the contacts are closed during measurement, the generator may fail. The generator works as follows: permanent magnets located in the annular rotor rotate around the stator windings, when rotating, an EMF is created in the generator windings, the amplitude of which is directly proportional to the rotor speed. Check the generator stator. between all three yellow wires. We do it like this: start the motorcycle, disconnect the generator connector from the relay-regulator, not forgetting to set the measurement mode in the tester to alternating voltage, the limit is 200V but not less than 100 volts.

At low revs and idling, the voltage should be around 50 volts, at maximum - up to 150. At engine rpm about 5000 thousand (It is desirable to keep the speed as accurate as possible) between the yellow contacts (1 - 2), (1 - 3), ( 2 - 3) the multimeter should show a voltage of at least 50-70 V, But the exact numbers are not important here, it is important that the voltage between any yellow wires is approximately the same at even turns. If there is no voltage, or \ "between the first yellow and the second yellow - 20 volts \" a \ "between the second yellow and the third yellow - 10 \" then - the generator is not working properly and needs repair or replacement. If the voltage is normal and the same, then the generator is alive, and the voltage regulator relay is faulty.

If the windings are in order, the relay-regulator is serviceable, the battery is "fresh", but the generator does not provide the required level of charge. The reason lies in the rotor, its permanent magnets partially lose their magnetic properties, which leads to a loss of generator power. This can happen when repairing a motorcycle, when storing the dismantled rotor next to metal parts.

THIS METHOD OF CHECKING THE GENERATOR IS RELATIVELY ACCURATE AND CANNOT GUARANTEE AN ABSOLUTE RESULT.

THE MOST COMPLETE AND ACCURATE CHECKING OF ALL PARAMETERS IS CARRIED OUT AT A SPECIAL STAND !

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