How to Check the Alternator in a Car?

Maintaining your vehicle is essential to ensure that it runs smoothly and reliably. Not only is it important to replace consumables when servicing your vehicle, but it's also important to make sure that key components are working properly. By regularly checking key components of your vehicle, you can prevent unexpected breakdowns.

The two most important elements of a car's electrical system are the alternator and starter. And when you need to check their technical condition, the most accurate way — is to dismantle them and check them on a special bench. But here there are two problems. Firstly, not every service station has a special stand for checking generators and starters used or new. Secondly, dismantling and installation of these components take a lot of time. That is why they are usually checked only superficially during maintenance.

What is the most common way to perform an alternator check on a car?"

The most common way to check the alternator on a car – is by diagnosing it with a multimeter. With a multimeter you can find out what voltage the alternator produces and if the value is within 13.8-14.6V, then the alternator is considered to be in good working order. This method of checking is enough for a simple «lamp» generator. However, a large number of modern generators have a digital, controlled voltage regulator. Generators with a controlled voltage regulator can disconnect the charging of the battery when it is fully charged. When such an alternator is checked by an unqualified mechanic, the peculiarity of its operation can be mistaken for a malfunction. Therefore, the multimeter test method is not effective for checking alternators with a digital voltage regulator.

The second method – checking the alternator with an oscilloscope. An oscilloscope provides voltage, frequency and waveform, which provides more information about the generator's operation than a multimeter. However, this method also has significant disadvantages:
1. oscilloscope does not allow you to identify the faults of the voltage regulator of the generator. And failures of the voltage regulator are on the first place of the reasons of the generator failure.
2. voltage measurement is usually performed at the battery terminals, which is a filter for voltage fluctuations. This reduces the accuracy and reliability of measurements.
3. Diagnosing an alternator with an oscilloscope requires a highly skilled mechanic.
4. As a rule oscilloscope — it is a stationary device and working with it in the place of car diagnostics is not convenient.

All these disadvantages lead to the low popularity of this method of checking the alternator.

How can you solve an alternator diagnostic problem on a car?"

The question of express diagnostics of the generator in the process of technical inspection is solved by using professional testers of car alternators, such as: MS015, MS013 COM and MS016. These testers are able to control the generator, as it does the control system of the car. This makes it possible to detect abnormalities in the alternator. However, these testers, like any other testers, are not able to detect all possible faults, only a special alternator test bench is capable of doing so.

The presence of professional automotive alternator testers will be of great benefit not only at the service station during maintenance and repair of cars, but also will be useful to repair shops for starters and alternators. In the workshop for repair of starters and alternators there is necessarily a stand for their diagnostics. With testers MS015, MS013 COM and MS016 you can expand the possibilities of existing equipment in terms of diagnostics of modern alternators with controlled voltage regulator.

Which alternator tester should I choose?

The MS015, MS013 COM and MS016 testers perform the same function but have different sets of options. For example, the MS015 tester has a minimal set of options and is only capable of testing 12V generators with a controlled voltage regulator. But such a tester can be bought for a low price. The MS013 COM tester additionally has the ability to check «lamp» generators and voltage regulator separately from the generator, and also has a single-channel oscilloscope mode.

The MS016 tester has the most options:

• Diagnosis of 12/24 V generators
• Diagnosis of 12 V generators of «start-stop» system.
• Diagnostics of voltage regulator separately from the generator.
• Reading data from any LIN bus of the car.

The most distinctive feature of MS016 tester is that together with a special cable MS-33503A it turns into a car starter tester. MS016 in starter tester mode can record voltage and current changes at the starter terminals during engine start. The result of measurements is displayed in the form of a graph, by which you can determine the presence of deviations in the operation of the starter, battery or wiring.

To make it easier to choose a car alternator tester, we have prepared a comparison table of all our testers.