Generators are used in many areas as autonomous sources of electrical energy. These devices are especially widespread in cars. Without a generator, blocks, devices and components that are completely dependent on the availability of electricity will not be able to work normally. It also charges the battery. Therefore, if any problems arise in the electrical system, one of the main questions becomes how to check the generator with a multimeter.
The best option would be to contact the service station for a complete diagnosis. However, this is not always possible, and the car may not be running. The only way out of this situation will be an independent check of all vehicle systems, including the generator.
How to check the diode bridge of the generator with a multimeter
The diode bridge in the generator is a kind of rectifier, with the help of which the alternating current generated by the generator is converted into direct current. It includes semiconductor diodes in the amount of 6 pieces, 3 of them - with a positive value, and 3 - with a negative value. Each of these groups passes current in only one, strictly defined direction.
Alternating current is used when it needs to be transmitted over a long distance. Electrical appliances installed in the car require direct current, including to charge the battery. Since the generator is capable of producing only alternating current, a diode bridge is needed to convert to direct current.
The design includes two metal plates that conduct electricity. Diodes are installed on their plane in order of priority. The alternating voltage produced by the generator changes the direction in which the electrons move. In order to obtain a constant voltage, it is necessary to redirect their movement in the so-called wrong direction, as a result of the further operation of the phases, a direct current will be created. In this circuit, it serves as a kind of capacitor, which successfully dampens voltage fluctuations. If necessary, check the generator with a multimeter.
Quite often, the diode bridge fails. A similar situation occurs when the polarity of the battery is not observed, or the electrical circuit is closed in the generator itself. Any malfunction of the diode bridge negatively affects the entire on-board network. If one of the diodes breaks or the diode is broken, in this case dips appear in the stable pulsating voltage at the generator output, since the faulty diode stops the voltage supply to the on-board network.
A certain compensation for failures is taken over by the battery at the expense of its own resources, however, the value of the total mains voltage is still reduced. In addition to instability, dips lead to electromagnetic interference that adversely affects audio equipment. With a large number of such violations, a mandatory check of the diode bridge is most likely required. To this end, you will have to check the generator for operability with a multimeter, after removing it from the engine. The diode bridge is disconnected and called by the tester.
During disassembly, it is advisable to use the instruction manual, since this operation may differ on different machines. On some models, the bridge is fastened with bolts, while on others it is simply soldered. Labels are applied to the diode bridge and generator to avoid confusion during subsequent assembly.
- The multimeter must be switched to the resistance measurement mode and set the sound indication.
- Next, the probes of the measuring device are connected to each output of the diode. The negative terminal - “minus” is connected to a central steel or aluminum plate, and the positive terminal is connected to a metal core made in the form of a tinned bare wire, the diameter of which must be at least 1 mm.
- To check each diode, you must first touch the core or central plate with one probe, and the opposite terminal of the diode with the other probe. After that, the probes must be swapped.
- If the diode is good, the multimeter will only beep when the probes are in a certain position. If the tester beeps with all connection options, this indicates that the diode is broken. If there are no sound signals at all, then the diode is open. Sound signals should be emitted by the device when only one side of the bridge is checked.
There is another method for checking the generator with a multimeter. In this case, resistance is used - the main physical quantity. To carry out measurements in this way, the switch must be set to 1 kOhm. Touching the probes is carried out as in the previous version. When checking one direction, the device should give a result of 500-800 ohms, and when checking the other - infinity. In this case, all bridge diodes are in working order.
How to test the generator voltage regulator with a multimeter
In order to ensure the normal operation of light bulbs, power windows, windshield wipers and other electrical equipment, as well as battery charging, you need to maintain a DC value of 13.5-14.5 volts. If this indicator is less, then the battery will not charge, and if it exceeds this level, the on-board electrical appliances will fail. High voltage also causes some damage to the battery, shortening its life due to overcharging.
Therefore, to convert the current generated by the generator, there is a special device -. With its help, the on-board network is provided with a current that maintains the required parameters, regardless of the crankshaft speed. Often there are situations when it becomes necessary to check the voltage of the generator with a multimeter.
Modern relays are electronic, and their design is non-separable. In the event of their failure, they cannot be adjusted or repaired, but require a complete replacement. This is considered the only drawback of these devices, since the rest of the relays have a lot of advantages: compactness, durability, high accuracy of current parameters.
- Headlights change the brightness of the glow, depending on the engine speed.
- There is an insufficient charge of the battery or, conversely, its overcharging, accompanied by the boiling of the electrolyte.
- There may be a burning smell in the vehicle interior. The failure of the regulator can occur due to moisture ingress, various mechanical damage, short circuits and other non-standard short-term electrical influences.
- Sometimes the regulator is initially of poor quality if it is a dubious product from unknown manufacturers.
There are different methods on how to check the generator relay-regulator with a multimeter and establish its performance. The easiest is to check with a multimeter, without dismantling the device. For this purpose, the voltage supplied to the battery to charge it is measured. For such a check, an assistant will be required to regulate the engine speed with the accelerator pedal.
The verification procedure takes place in several stages:
- The car engine starts and warms up within 5 minutes.
- Open the hood while the engine is running and connect the multimeter leads to the battery terminals. The connection must be made in accordance with the polarity, and the switch is set to 20 V.
- The evaluation of the charging voltage from the alternator is carried out under certain conditions. You need to check how much the generator produces with a multimeter. The dipped beam must be on, and all other consumers must be off. The crankshaft rotates at a speed of 1.5 to 2.5 thousand rpm. If the voltage is more than 14.8 volts, then the regulator is considered defective and must be replaced. At voltages below 13.5 V, the relay may not be the cause of the malfunction. The fault may lie in the wiring or the generator itself.
- More accurate results are obtained by estimating the intensity of the current flowing at the load. This will require the inclusion of high beam, stove fan, windshield wiper and other consumers. In such a situation, the value of the charging current should not be lower than 13.5 volts. If the indicator is still less than this value, then when all electrical equipment is turned on, the battery will not receive a normal charge.
A more complete check is performed on the removed relay-regulator. Usually the electronic device sits on top of the generator, covered with a plastic cover. In some cases, the regulator may form a single unit with the brushes. To check, in addition to a multimeter, you need to prepare a 12 V test lamp, with a power of not more than 3 watts, and an adjustable current source. These methods are also suitable for checking the generator integral with a multimeter, that is, an integrated voltage regulator.
The wires from the current source are connected as follows: the "minus" is connected to the regulator's ground, and the "plus" is connected to the terminal marked with the symbol "B". The control lamp is connected through conductors to graphite brushes without observing the polarity. First, a voltage of 13 to 13.5V must be applied to the relay-regulator, at which the light will be on. If this does not happen, then the control device is faulty.
Further, the light bulb remains in a burning state, and the input voltage gradually increases. With a working relay, the light will go out when the voltage reaches 14.2-14.5 V. If, in the event of a further increase in voltage, the control light continues to light, then there is a breakdown in the relay and it is faulty. A malfunction is also indicated by the fact that, at a voltage below 4 V, the light goes out. Such a current will be clearly insufficient to provide power to all electrical appliances and to charge the battery with high quality.
How to check the generator rotor with a multimeter
A faulty car alternator rotor primarily causes the charging current to fail and the battery to drain. This is indicated by the low battery light located on the instrument panel. The position of the voltmeter needle is near the red zone or in the zone itself. In this regard, it becomes necessary to check the generator armature with a multimeter.
When checking the voltage with a multimeter with the engine running, its readings at the battery terminals will be less than the required 13.6 volts. In order to obtain more accurate results, it is recommended to check the battery charging from the generator with a multimeter in advance.
The main malfunctions of the rotor are considered to be a short circuit of the windings and a break in the leads between the excitation winding and slip rings. To check, it is not necessary to remove the generator from the engine and remove the rotor from it. It is enough to remove the voltage regulator relay and perform all the necessary actions through the resulting window.
In order to check for a short to ground in the excitation windings of the rotor, you need to set the multimeter to the mode and press the positive probe one by one against the slip rings. The negative probe is pressed against the mass - the generator housing. If the resistance indicator tends to infinity, then the rotor is working and there is no short to ground. After that, you should check the generator winding with a multimeter for an open circuit. The multimeter is also set to ohmmeter mode, the positive probe is applied to one slip ring, and the negative probe to the other. A resistance value of 5 to 10 ohms indicates the health of the excitation winding. In most cases, a defective rotor must be replaced.
However, not all elements can be verified by testing. For example, it is not possible to check the generator brushes with a multimeter. This procedure involves visual diagnosis after the removal of the brush apparatus. If necessary, the voltage regulator can also be removed. As a rule, the brushes show uniform wear. In normal condition, the length of the brushes is 8-10 mm. If this figure is less than 4.5 mm, then the brushes must be replaced. At the same time, the coal dust formed as a result of the friction of the brushes on the rotor rings is cleaned.
When performing generator diagnostics, rotor failure is the last resort. First of all, other elements that are more likely to cause malfunctions of the device are checked. Low voltage, a burning light on the instrument panel and other symptoms can happen if the diode bridge or relay regulator fails. First they are checked, and only then the rotor itself.
Vehicle battery and alternator check
How to check the removed generator?
The generator is one of the most important elements of the car, it is responsible for the correct operation of all components that need electricity. Of course, if the car has problems with the power supply, the first "culprit" is the generator. That is why it is important to be able to check it yourself. Let's figure out how to check the operation of the generator using a tester (multimeter).
Checking generator elements
The generator has 4 main components, the performance of which gives a complete picture of the functioning of the generator. If one of the elements is faulty, then the generator will not be able to work correctly. Thus, to check the generator, you need to check each of the elements.
Relay
- We turn on the multimeter in the DC voltage measurement mode.
- We start the car.
- We measure the voltage at the battery terminals - the value should fluctuate in the range of 14 - 14.2 V (otherwise, the relay is faulty).
- We press the accelerator, monitor the voltage - it should increase by 0.5 V (otherwise, the relay is faulty).
Diode bridge
- Turn on the sound mode on the multimeter.
- We "call" each diode (there are 6 of them in the bridge) in both directions.
- If all the diodes "ring" in only one direction, they are working, otherwise they are not.
generator stator
- Disconnect the diode bridge from the stator.
- We inspect the winding - there should be no soot and damage.
- Switch the multimeter to resistance measurement mode.
- We measure the resistance value between the stator housing and the winding.
- If the value is much more than 50 kOhm, the stator is healthy, if the value is close to 50 kOhm, it will soon fail, less than 50 kOhm, it is faulty.
generator rotor
- We take out the rotor and inspect for visible damage.
- We check the integrity of the winding.
- We measure the resistance between the contact rings.
- If the resistance value is equal to several ohms, the rotor is corrected, if the device shows zero or infinity, no.
That's all the checks that need to be done with the generator. If all checks showed that the generator is working, then you need to look for the problem further.
A generator is a small power plant for a car. It not only supplies consumers with energy, but also. Despite the fact that battery manufacturers claim that their batteries are capable of running the engine and driving "on the battery" for at least 200 km, tests have shown that no battery "holds up" to the declared indicators.
Therefore, even while within the city, if you suspect a breakdown of the generator, it is better to immediately check its operation - otherwise, a “dead” battery due to insufficient charging may prevent the engine from starting and thereby disrupt plans for the day.
Let us consider in general terms the device of this node, its possible malfunctions and their identification on the removed generator, and we will also tell you how to check the generator on the machine without removing it.
Generator device
Figure 1 clearly shows the generator in disassembled form, Figure 2 shows its electrical circuit.
Its principle of operation is simple - the generator pulley is driven by a belt, which is also worn on the crankshaft pulley. On modern cars, this belt usually transmits torque to other engine mechanisms, so it is commonly called a service belt.
The voltage regulator in modern generators is compactly made in one housing with a brush assembly to save space.
A rotating rotor, the winding of which is supplied with an electric current through copper-graphite brushes (to create an electromagnetic field), generates an EMF in the stator winding, the “positive” terminal (in Fig. 2 “B”) of which is connected to the battery, and the negative one to the “mass” .
Naturally, with an increase in the number of revolutions of the engine, the current generated by the generator also increases. Excessive voltage can damage not only the battery, but also most electrical appliances in a car. Therefore, a voltage regulator is installed in the rotor winding circuit, which limits the current supply to the rotor winding and thereby changes the voltage generated by the stator.
The voltage regulator in modern generators is carried out in one product with a brush assembly, thanks to the use of semiconductor switches - older models of regulators were of the relay type and were installed separately - due to their bulky dimensions.
The diode bridge of the generator serves to convert alternating current to direct current and, as can be seen from Fig. 1, is installed inside the generator.
Generator malfunctions
Faulty alternator bearing
Generator failures can be divided into two groups - mechanical and those that are typical for electrical appliances. Mechanical failures are fairly easy to diagnose when inspecting the generator and its drive. Worn bearings in the generator itself and in the tension rollers of the service belt give themselves out with a buzz, the belt tension is usually controlled by hand. The service belt itself is simply enough to carefully inspect for cracks, delamination, oiling, etc.
Breakdowns of the electrical part, as a rule, require instrumental control (tester, multimeter, oscilloscope) and can be as follows:
The most common alternator failure is wear and tear on the brushes.
- Wear and tear of brushes.
- Breakdown or burnout of the voltage regulator integrated circuit.
- Diode bridge malfunctions - burnout or breakdown of its valves.
- Partial or complete combustion of the insulation of the wires of the rotor and stator windings.
Breakdowns can lead not only to insufficient voltage generated by the generator. A breakdown of the voltage regulator circuit, on the contrary, can contribute to the fact that all the current generated by the generator will flow into the on-board network of the car - and this can be from 30 volts and above, which will cause the electronic devices to burn out and the battery to “boil away”.
How to check if the generator is running on a car
Checking battery voltage
An oscilloscope will give the most complete picture of the generator, but reading the oscillograms requires special training, and describing the diagnostics will take a lot of time. Therefore, we will not describe how you can check the generator on the machine with an oscilloscope, but we will describe more accessible methods.
To check the generator without removing it, you should measure the voltage at the battery terminals with the engine running - it should be about 14 volts.
The easiest method is to remove the terminal from the battery while the engine is running - if the engine stalls after that, it means that the generator is not doing its job. The method is effective and visual, but it is only good if the old type voltage regulator is a relay one. Modern semiconductors do not always withstand a power surge, and diode bridge valves do not work without load, so such a check can destroy electronics that were working before.
It is best to measure the voltage at the battery terminals with the engine running - it should be about 14 volts (with powerful consumers turned off) at idle.
In addition, a “non-supplying” generator manifests itself as follows:
- when driving at low speed in the dark, the headlights “tremble” a little - this is a faulty voltage regulator;
- the operation of the generator is accompanied by a characteristic “howl”, which intensifies when electrical appliances are turned on, and the headlights become dimmer at the same time - the diode bridge is faulty;
- the sound of a service belt slipping on the pulleys is familiar to almost everyone. A slipping belt also reduces the performance of the generator.
How to test a generator without a car
Checking the generator brushes
Do not rush to disassemble the entire generator removed from the car at once. The wear of the brushes is not a breakdown; rather, their replacement can be considered as a kind of prevention. Check alternator brushes it is best to remove them as an assembly with the regulator - an inspection will show not only how worn they are, but also allow you to identify their possible jamming.
In order to check voltage regulator generator, it is not enough to use only a tester or multimeter - you need to make sure that it really does not allow excess voltage supplied to the brushes - and through them - to the rotor winding.
To test the generator regulator relay looks something like this (Fig. 3):
Checking the voltage regulator relay
But, using a conventional 12-volt battery as a power source, you can only state an open circuit (in the event of an integrated circuit burnout) if the control light does not light up. But if instead of a battery you connect an adjustable power supply and apply a voltage of more than 14.4 volts, a working regulator should lock the circuit and the light will not light up.
Checking the diode bridge of the generator
To check diode bridge generator with a multimeter, you need to turn on the device in the semiconductor test mode - an audible signal with a diode connected in direct polarity will indicate that the diode has not burned out. When connected in reverse polarity, such a sound will indicate that the diode is “broken”. But sometimes faulty diodes can be seen with the naked eye - it happens that they are torn in half.
If you don’t have a multimeter for “dialing” at hand, an ordinary incandescent lamp will help you get out of the situation.
But if there is no multimeter at hand, the “ringing” of the bridge with the help of a lamp will be no less effective.
To check for an open circuit in the rotor and stator windings, a simple probe with a light bulb is sufficient, but an interturn short circuit can only be detected by measuring the resistance with an ohmmeter. But if the stator winding burned out, this can be determined by the darkened insulation and the smell of burning.
If you removed the generator, but are not sure that you can fully diagnose it, you can take it to a specialized workshop, where they will check it on a special stand.
The constant undercharging of the battery or its absolute discharge at the most inopportune moment is a headache for many car owners. One source of these problems could be the alternator. But how to check it? Maybe it's not about him at all? Let's figure it out together how much the generator should produce for the normal functioning of all car systems and maintaining the battery in a charged state.
The battery in the car is an important element of the system, which is responsible for providing the on-board network of the car with electricity. The generator is used to charge the battery while it is active. Unstable operation of a device that generates electricity causes a voltage drop in the network and a lack of restoration of the power source capacity.
The normal performance of the generator is understood as the timely and full replenishment of the battery charge level, which decreases under load. Checking the amount of battery charge from the generator is simple and can be done by the car owner on their own.
Diagnostics of an automotive energy generating device includes a visual inspection of the unit, its elements and related parts, as well as the measurement of voltage and current. At least twice a year, the tension of the drive belt should be checked, excessive loosening of which leads to a decrease in the performance of the generator, and sometimes can lead to a breakdown of the device. Once a year, you can check the elements of equipment - fasteners, diode bridge, voltage regulator and others. Timely maintenance of the battery will also guarantee the absence of problems - cleaning the terminals, adding distilled water.
Diagnostics of indicators such as voltage, current, resistance is also required twice a year. For its implementation, you will need special devices - a voltmeter, multimeter or load plug.
How much charge should go to the battery from the generator
It is traditionally believed that 13.5-14.5V should be supplied by the generator to the battery and this is completely enough to make up for the cost of the battery.
It should be borne in mind that the use of a battery with more power than the manufacturer recommends in a car requires the installation of a more efficient generating device.
It is necessary to take into account the load that the generator must withstand - it is calculated according to the maximum performance of all electrical appliances and auto systems.
Do not forget that the charging current from the device that generates energy will allow you to start the car in the cold season. In order to avoid problems with the car factory, we recommend purchasing generating equipment, the charge current of which will be approximately 10% of the power source capacity. That is, for a battery of 100 A / h, a generator is needed that can produce 10A. Note that for many cars, 100 amp equipment will be pushed to its limit because the power consumption of the car system is around 80 amps. Therefore, the choice of a source that generates energy must take into account both the battery capacity and the consumption in the network.
How to check alternator voltage on battery
The potential difference can be diagnosed in two ways - directly on the generating equipment and through the battery. The generator is directly connected to the power source with a thick wire, therefore, to check the level of potential difference, you can measure the voltage at the power source. This will require special devices - a voltmeter, multimeter or load plug.
The wires of the first measuring instruments are connected to the battery in any sequence. The plug must be connected to the battery terminals with strict polarity. It is generally accepted that the normal voltage in the network should be at least 12 volts. At idle without turning on all the electrical devices of the car, this indicator should be at the level of 13.5-14V. A drop in voltage values to 13.3-13.8 volts is considered acceptable.
At the same time, conventional testing equipment can check the resistance of the generator elements - rotor, stator and diode bridge. Diagnostics of rotary equipment is carried out by its winding. It is necessary to connect the probes of the device with slip rings. If the multimeter gives readings from 2.3 to 5.1 ohms, then this element is working. The current consumption of the winding should be within 3-4.5 amperes.
Its normal resistance is 0.2 Ohm. The diode bridge is checked by the presence or absence of resistance, the indicators do not matter. The only thing worth considering is that there should not be a zero dimension. Measurements are carried out in pairs - positive exit and all plates on this side or minus and all elements.
We remind you that for normal charging of a car battery, the voltage supplied by the generator must be from 13.5 to 14 volts.
How many amps does a car alternator put out per battery
The current strength required by the electrical system of each car is individual and depends on the number of electricity consumers and their values. And also the charge current must be sufficient to charge the power supply.
It is worth noting that ampere readings appear only when there is a load in the car's electrical system and, accordingly, the battery is discharged. After starting the engine of the car, the charge current is about 6-10 amperes and drops over time, because the battery is charging, which takes on the main energy consumption. If you turn on additional equipment - headlights, radio or heated mirrors, you can see an increase in the charging current.
When buying a generator, pay attention to its technical characteristics, which the manufacturer indicates on the case - this is where you will find information about how much current will be supplied to the battery as much as possible.
In the table below, you can see the approximate values \u200b\u200bof the current strength that the generator shows at different loads.
Table 1. How many amps does the generator produce under load.
Signs of a malfunctioning generator
In modern cars, breakdowns in the electrical system are one of the most common. A large number of electronics obliges you to carefully monitor the operation and condition of the generator and battery, because their failure can immobilize the car. The most common signs of a generator failure are:
- light indication of the battery on the instrument panel;
- unstable operation of the battery (its boiling over or undercharging);
- different intensity of headlights;
- extraneous sounds from the generator.
If you notice incorrect operation of the car, then perhaps the battery charging current from the generator is insufficient.
All malfunctions of electrical equipment, to which the vehicle’s energy-generating device belongs, are mechanical (deformation or breakage of fasteners, housing, malfunction of bearings, clamping springs, drive belt, etc.) or electrical (winding breaks, malfunctions of the diode bridge, burnout or wear of brushes , short circuits between turns, breakdowns, etc.).
Don't write off a broken generator: find out if there are repair kits and spare parts. Replace them if possible. If you cannot carry out repairs yourself, then take the generator to a workshop. Many craftsmen will be able to restore the unit at no extra cost and in the shortest possible time.
However, individual breakdowns require the purchase of a new device that generates electricity. For example, a failing bearing that is soldered into the generator housing cannot be repaired or replaced in most cases.
Remember that the failure of this unit can be caused not only by wear and corrosion, but also by the poor quality of the elements and components; excessive load; external influence of salts, liquids, temperatures.
Other causes of low voltage
Not always a small potential difference in the system is associated with a breakdown of the generator or a bad battery. If the diagnostics of these elements did not reveal any problems, then you should pay attention to the following:
- the condition of the battery terminals - junction density and oxidation;
- wiring problems - oxidation, violation of its integrity;
- output contacts to electrical appliances;
- correctly selected energy consumers.
Each contact must be tightly adjoining and integral, that is, the absence of formations (for example, sulfation) that will interfere with the passage of current is necessary. Incorrect connection of the contacts leads to an accelerated discharge of the battery even when the car is not running.
To improve the connection of the elements of the electrical system of the car, it is necessary to strip all contacts and restore the integrity of the wires by replacing them or connecting and winding them with insulating tape.
In conclusion, I would like to repeat that the stable operation of the car requires constant monitoring of all elements, and the generator should attract special attention. The battery is charged from it and provides electricity to the entire automotive system. Pay attention to all the elements: generator brushes, slip rings, voltage regulator, equipment winding.
The most correct measurements should be taken when the battery is fully charged and in various modes. Remember that the manufacturer ties the characteristics of the generator to the number of engine revolutions - they help to generate a certain current.
Detailed video on how to check the generator:
Do you have experience diagnosing a generator and solving problems in a car's electrical system? Please share your experience and opinion with our readers in the comments. If you have questions about the topics covered, we will be happy to answer them.
Good afternoon. In today's article I will tell you how to check the generator on a car without removing it. Traditionally for our site, the article contains a lot of photo and video materials.
How does a generator work and why is it needed?
In modern cars, there are many consumers of electricity - from car radio to. For the operation of all these consumers, electrical energy is needed. Its main supplier is the generator. When it cannot cover all needs, for example in a traffic jam, the energy stored in the battery is consumed. After conditions are met, the generator replenishes the battery charge.
At the slightest malfunction of the generator, there may be problems with replenishing the battery charge and, as a result.
You can clearly see the principle of the generator in this video:
How to check the electrical part of the generator?
This is done with a special device - a multimeter. It is sold in any hardware store and costs 500-700 rubles, or you can order it directly in China, and it will cost, without trade margins, 300-350 rubles.
The verification scheme is as follows:
We turn on the multimeter in the voltage measurement mode up to 20 volts DC.
We fix its probes on the wheels of the generator, with a fully charged battery, the device will show 12.5-12.9 volts.
We start the engine, and let it run at high speed for 4-5 minutes.
If the generator is working, the voltage will rise to 14.5-14.7 volts.
We gradually turn on consumers (headlights, interior heater, glass heating, music, seat heating) and control the voltage. Even at idle, it should not be lower than 13.5 volts.
If so, your alternator is good.
Here is a video of checking the generator with a multimeter:
If you do not have a multimeter, then the generator can be checked without it, but the accuracy of such a check is not high.
This is done as follows:
- Loosen the negative terminal on the battery.
- We start the engine, let it run, so that the idle speed decreases.
- Remove the negative terminal from the battery.
If the engine does not stall, the generator can be considered serviceable. “Gasing” with the terminal removed is unacceptable!
Here is an example video of removing the battery from a car with the engine running:
Important notes.
Many cars are equipped with a voltmeter, but its readings can be trusted very conditionally, since the accuracy of its readings is not great and often differs by 0.5-1 volts in any direction.
Checking the generator by removing the terminal is not always acceptable - not everywhere there is good access to the battery, but on complex cars, such a check is fraught with errors and the ignition of a warning lamp, check the engine.
Deal- it is safer to check the electrical part of the generator with a multimeter, measuring the voltage on the battery. In extreme cases, it is permissible to check the generator by throwing off the negative terminal.
How to check the freewheel without removing the alternator belt?
About the appointment and verification of the overrunning clutch on our website, therefore, briefly.
When the engine is running, the overrunning clutch should not creak or make noise.
With the engine turned off, use a thin screwdriver to turn the generator armature.
Ideally, it should scroll in one direction and sideways in the other. Here is a visual video for you:
If the overrunning clutch jams, the alternator belt, with extreme wear, may simply come off.
How to check alternator bearings?
In a good way, to check the bearings, it is necessary to remove the alternator belt. This is the only way to fully check the play and noise of the bearings.
There is an old-fashioned method of listening to bearings.
You will need a metal bar of sufficient length.
With the engine running, we rest the bar against the generator, and bring the other end to the ear (ATTENTION, you can’t put the bar in your ear, you will hear everything clearly anyway).
It's done like this:
Conclusion.
I hope that after reading this article, you understand how to check the generator on a car without removing it.
Brief algorithm:
- started the engine, threw off the negative terminal, the engine did not stall - OK
- heard that the bearings are not noisy - OK
- if the generator is equipped with a freewheel, checked it - OK
If all these points are fulfilled, the generator can be considered serviceable.
That's all I have today. If you have any questions or want to supplement the article, write comments.
