What is the voltage the automotive alternator has to generate?

This is the question people ask when they have trouble starting the engine and need to check the alternator. Alternator output voltage is a key characteristic. For most cars, between 13.8 and 14.4V is normal, regardless of engine operation and the number of consumers switched on. Refer to the vehicle's owner's manual for exact values.

But is it enough to measure the output voltage to determine if the alternator is working properly? No, it is not. A voltage reading that doesn't match normal is usually the cause of a voltage regulator failure. For other faults, the voltage is more likely to remain normal.

It's also worth bearing in mind that modern car alternators use digital and controlled voltage regulators. And they can fail not completely, but by losing the ability to fulfil one of their functions. For example, the voltage regulator has stopped transmitting to the engine control unit a signal via the FR feedback channel. This will lead to the fact that the generator will constantly work in the mode of charging the battery. This failure will not be displayed on the dashboard and will not be an error when diagnosing the car with a diagnostic scanner. At the same time such breakdown will not have negative consequences for the car, which will be operated in the city. But if the car will be travelling constantly on long distances, between cities, then the battery will constantly experience overcharging and will quickly lose its capacity.

Therefore, a reliable and comprehensive assessment of the technical condition of the alternator is only possible with specialised equipment, which will allow you to check all the output characteristics of the alternator.

MSG Equipment has developed a whole range of generator diagnostic test benches:

• Budget segment for garage workshops and small service stations is represented by standsMS006 COM and MS004 COM. These stands have enough power to diagnose alternators of passenger cars.
• Large remanufacturers are more suitable for the standsMS002 and MS008. With high power, these benches can diagnose alternators under a wide range of loads. Both can test alternators, starters and voltage regulators separately from alternators.
• Our most powerful standMS005 will be useful for designers and manufacturers of starters and alternators, as well as rebuilders who repair starters and alternators of trucks.

To learn more about the capabilities of the alternator diagnostic equipment, please ask our managers.