Starter vs alternator, alternator and starter troubleshooting?

The alternator is an important part of the vehicle electrical system, and its main function is to convert the mechanical energy generated by engine rotation into electrical energy to power the electrical equipment of the entire vehicle.

The principle of the alternator is to use the principle of the interaction of magnetic field and electric current to generate alternating current through the relative motion of the rotor and stator. Inside the generator, the rotor and stator contain magnetic poles and coils, respectively. When the relative motion of the rotor and stator occurs, the magnetic poles excite an electric current, which produces an electrical output in the coil.

The output voltage and current of an alternator are more stable and suitable for high power loads, so it is widely used in automotive and industrial applications.

The starter motor is another important part of the automotive electrical system, and its main function is to convert electrical energy into mechanical energy so that the engine can start normally.

The principle of the starter motor is to use the magnetic field generated when the current passes through the coil to act on the armature, so as to make the armature produce rotary motion. When the armature rotates to a certain speed, it will drive the engine to rotate, thus making the whole engine system start.

Starter motors are generally suitable for lower power loads and are only needed when the engine is started, so their role in the automotive electrical system is relatively short-lived compared to that of a generator.

Third, the relationship between alternator and starter motor

Alternator and starter motor are two key components in the automotive electrical system, and their roles complement each other to ensure the normal operation of the entire automotive electrical system.
When the vehicle is running, the alternator works in power generation mode, converting mechanical energy into electrical energy to provide electrical support for the whole vehicle. When the vehicle starts, the starter motor works in starting mode, converting electrical energy into mechanical energy to drive the engine to start normally.

In this way, the alternator and the starter motor collaborate with each other to provide power and start-up support for the vehicle, bringing more protection and convenience to the driver's driving experience.

(1). There is a "clicking" sound when the starter is switched on and off, but it does not work. This phenomenon can be caused by a broken wire of the holding coil or a serious loss of power in the battery.

(2). Starter motor power output is insufficient to drive the crankshaft. Insufficient starter power can be caused by a short-circuited excitation coil and a weak battery.

(3). Harsh sound of starter motor operation. This may be caused by a stuck freewheel or improperly installed starter.

(4). The starter motor does not operate properly and the drive gears do not turn. There are many reasons for this phenomenon, such as problems with the power cord, burnt contact discs on the starter switch, and excessive engine resistance.

(5). When the starter switch is switched on, the starter motor rotates at high speed and the engine crankshaft does not respond. This phenomenon indicates that the fault occurs in the transmission mechanism of the starter motor, which may be caused by the wear of the transmission gears or the freewheel.

(6). The starter motor often fails to rotate or rotates slowly, in this case, should be checked from the following aspects:

Automotive generator failure solution:
Engine speed above medium, the ammeter pointer indicates not charging, charging indicator light, first consider the battery charging situation, if the charging is insufficient for power generation device failure.
Not charging in addition to the drive belt is too loose slippery, generally check the generator itself does not generate electricity or regulator failure, as well as charging circuit disconnection failure. Such as generator internal rectifier off or armature terminal bottom and diode element board contact place can not be; diode breakdown short circuit, resulting in stator winding burn; brush in the carbon brush holder stuck in poor contact, or magnetic field winding disconnection.
Diagnosis in raising the engine to turn ;turn on the headlights, such as the ammeter pointer momentary deflection discharge direction, it is the generator and regulator work normally, but the battery charging has been enough; if the ammeter pointer larger deflection discharge direction, then the fault is in the generator or the regulator, you should check the charging line of each connector is good, whether the fan belt is too loose and the generator, the regulator's technical condition. First of all, verify whether the charging system is indeed faulty, the engine will be placed in medium-speed operation, in the moment of opening the headlights, the ammeter needle bias to the "+" direction or to keep the original position does not move, for the battery has been sufficiently charged, charging system is working properly. If the ammeter pointer to "a" direction, for the charging system has a fault, should be overhauled.

Automotive generator fault solution:

Battery in the case of insufficient storage, increase engine speed, the ammeter pointer indicates a small charging current, the charging current is too small fault. This is generally caused by insufficient voltage of the generator itself, poor technical condition of the regulator and increased resistance in the charging line.

Can be judged and eliminated according to the following steps: check the battery, generator, regulator and ammeter and other parts of the terminal and its wire connection is secure. Check whether the fan belt is too loose and the generator speed is not high. When the above conditions are normal, check the limit voltage of the regulator at medium engine speed, and dismantle the generator to see if there is any abnormal phenomenon of wear and damage. Check whether the regulator activity contact erosion or oxide, activity contact arm and iron core gap and spring tension is in line with technical requirements; regulator wiring has no loose phenomenon. Abnormalities found should be repaired in a timely manner. Engine running at or above medium speed, turn on the headlights, if the current still shows charging, charging system is in good technical condition; if the power meter shows discharge, charging current is too small fault, should be overhauled.

Car generator fault solution:

Car ammeter needle deflection to the maximum charging current position; if the night driving, engine speed is high, there will be lighting and instrumentation indicator lamps are particularly bright. The bulb is easy to burn out, the distributor contacts are eroded, and the battery electrolyte is consumed too quickly. First of all, check whether the regulator fire wire and magnetic field two terminal wires are connected to the wrong, whether the active contacts are eroded or bonded to the normally closed state. Check the regulator, you can remove the magnetic field wiring, if the charging current is significantly reduced for the regulator failure, may be the low-speed contact sintering can not be separated, the coil has a broken circuit, etc., if the charging current is still very large, it may be the magnetic field wiring and the armature wiring has a short circuit. First check whether the battery internal short circuit and serious power loss caused by charging current is too large should be overhauled.

Automotive generator fault solution:

In the engine idle speed above the speed operation, the ammeter pointer swings left and right, showing intermittent charging (sometimes charging and sometimes not charging phenomenon), generally for the generator's end voltage instability. First of all, you should check whether the connecting wires are loose and poor contact; whether the belt is too loose as well as whether the battery stakes are loose. If there is no abnormality and then check whether the regulator contacts are corroded, dirty, coil or resistor has no poor contact, disconnection, etc.; still no abnormality, it should be disassembled to check the internal technical condition of the generator, and repair one by one. When the generator is running above medium speed, the ammeter indicates charging, but the pointer keeps swinging left and right, and the charging current is sometimes large and sometimes small, it should be overhauled.

Automotive generator failure solutions:
Generator does not generate electricity is mainly due to: rectifier diode breakdown short circuit or disconnection; excitation winding short circuit or disconnection; three-phase stator winding phase short circuit or lap; rotor slip ring serious oxidation dirty, carbon brush holder damage or carbon brush stuck in the brush holder.

A faulty starter may be too slow to slowly start the engine as quick to get started, or it may not crank the engine at all. Often, the problem is not the starter, but a low battery charge or loose or corroded battery cable connections. So, check the battery charge and condition first.

A good battery should be able to accept and hold a charge from a battery charger and should be at least 75% charged (12.5 volts or higher). If the battery is low voltage and will not charge, your customer needs a new battery. Performing a load test on the battery or using a conductivity tester to check its charging and storage capacity will also confirm the need for a replacement battery. The average lifespan of a car battery is only four to five years, and in hot climates it can be even shorter. So it's important to consider the age of the battery as well when assessing its condition.

If a DIY customer isn't sure what's causing his cranking problems, offer to bench test his old starter. If the starter passes the test, then the slow start or no-start problem is obviously not related to the starter. He should check the battery, battery cables, starter relay and starting circuit and wiring connections for possible faults. If the starter fails the test due to low starting speed, too much current or no rotation at all, you can sell the customer a new or remanufactured starter with a high degree of confidence.

High resistance in the starter itself, worn brushes, and grounded or disconnected armature or coil windings can cause excessive current. It can also be caused by increased internal friction due to bound bushings or armatures or magnets rubbing inside the starter.

A loose starter can crank an engine slowly or not at all. Loose bolts will provide a weak ground connection. The starter can also flip, slide, chatter or fail to make contact depending on how loose it is. Even if the starter will spin, sometimes the engine will not crank. This is usually an engagement problem caused by a weak magnetic solenoid or defective starter drive. A starter drive on the verge of failure may engage briefly, but then slip. The starter drive has a way of outrunning the clutch mechanism and can be checked to see if the starter is checked (and replaced if necessary) from the car. The driver should turn freely in one direction, but if it is good. A bad drive will turn freely in both directions or not at all. If the drive locks up it can over turn and destroy the starter.

When the alternator fails, the first sign of trouble is a low or terminal battery. On delayed model vehicles, this can cause not only a disabled start, but also a loss of "learned" data in the powertrain control module and other modules throughout the vehicle. In some cases, certain modules may not regain their normal functionality because they require special REREARN procedures.

The output of the charging system on the vehicle can be checked with a digital voltmeter while the engine is idling. Normal operation of the charging system should produce a charging voltage of approximately 13.5 to 14 volts (always refers to the vehicle manufacturer's specifications) at idle in the idle condition. When the engine is first started, the charging voltage should rise rapidly to approximately two volts above the base battery voltage and then taper off to cross out at the specified voltage.

The exact charging voltage will vary depending on the battery's state of charge, the load on the vehicle's electrical system and the temperature. The lower the voltage, the higher the charging voltage, and vice versa.
If the charging output is low, the alternator can be qualifying test to see if it is good or bad. Make sure the correct wiring adapter is used for the unit and that all connections are properly complete. A bench tester will check the alternator's voltage and current output and look for "ripple voltage" or AC leakage, which indicates a bad diode inside the alternator.

If the alternator fails the test, your customer will need a new or remanufactured replacement alternator. If the customer's vehicle is equipped with a megawatt aftermarket sound system or other high-duty electrical accessories, you can use this opportunity to recommend a higher output alternator.

If the alternator passes the test, the problem is not the alternator, but something in the wiring or charging system control circuit. High circuit resistance and ground resistance can cause low charging output. Circuit resistance can be checked by connecting a voltmeter to the positive battery terminal and the positive alternator terminal. With the engine running and headlights on, there should be less than a half volt drop, preferably less than a tenth of a volt drop. Higher readings indicate excessive resistance. The same test can be repeated using the negative battery terminal and alternator housing to check for excessive resistance on the ground side of the circuit.

If the wiring checks out fine, the problem may be in the voltage regulation circuit within the powertrain control module. On many newer vehicles, the charging output can vary depending on operating conditions and electrical load. Problems with other sensor inputs or defects in the control module itself may prevent the generator from charging properly.

Slipping drive belts are another common cause of undercharging, especially the v-belts found on older cars. A serpentine belt usually provides better grip, but it can allow the belt to slip under load if the auto tensioner is weak or stuck. Glaze streaks on the belt or belt noise when a high load electrical accessory is turned on with the engine idling can be signs that the belt is slipping.

Alternator slippage and underrunning can be caused by the alternator pulley. Overrunning Alternator Pulleys (OAP) are used on many late model import and domestic vehicles.OAP Pulleys have a freewheel within the centre of the pulley that slips the centre of the pulley and allows the pulley to go to the freewheel when the engine speed drops suddenly. This reduces noise, vibration and irritation in belt-driven systems, but can cause charging problems if the clutch grips when it should.

Another type of pulley is the over alternator decoupler (OAD) pulley. This type of pulley combines a one-way clutch with a torsion spring to decouple and absorb torsional vibration in a belt-driven system. This provides quieter and smoother operation than a solid pulley or OAP, especially at lower engine speeds (from idle to about 1,500 rpm). But it can also cause slipping and charging problems if the clutch or decoupling spring is defective.

Some replacement alternators come with pulleys already installed, some do not. If the replacement alternator is equipped with a pulley, make sure the pulley matches the original (same diameter, width and belt type). The absence of a pulley means that your customer must exchange the pulley from the old alternator to the replacement. Removing a conventional solid pulley usually requires a gear puller to pull the pulley off the alternator shaft. However, in some applications, threaded rubber or OAD pulleys can be used and may require special tools to make them close.

OAP and OAD pulleys are more complicated and expensive than regular solid pulleys, but are installed on the alternator for a reason. Replace an Oatmeal or OAD pulley with a cheaper solid pulley, and some replacement alternators have cheaper solid pulleys rather than overrunning clutch or decoupling pulleys. But replacing an oatmeal or OAD pulley with a solid pulley defeats the purpose of the original pulley and can lead to increased NVH, reduced belt and tensioner life and customer complaints.

A new drive belt is also recommended when a new or remanufactured alternator is installed on a high mileage vehicle. OEM belts made from EPDM synthetic rubber are high sealevel belts capable of lasting up to 100,000 miles. Unlike older belts made of more durable rubber, they don't break with age. But they do wear. It's hard to see the grooves underneath the belt grooves can wear out, so belt manufacturers have created special belt wear tools that can check the depth of the grooves to reveal how much wear they're getting.

Automatic belt tensioners should also be checked for operation to make sure they are working properly and maintaining proper belt tension. Rust and corrosion can cause an old tensioner to go taut, and a weak or broken spring may prevent it from keeping the belt tight.