UK Suppliers of Alternators
Coach and Bus
Special Vehicle Builders
Van Conversion Specialists
Many 12v and 24 volt automotive alternator removals and replacements can be carried out on site.
Battery test and vehicle charging system testing available.
Troubleshooting of alternator charging circuit problems
Auto electrical diagnostics wiring faultfinding and repair.
Test and repair facilities for many vehicle rotating electrics units
The automotive alternator is an alternating current (ac) electricity generation plant with rectification to direct current which provides electrical power output whilst the vehicle engine is running, to recharge one or more vehicle batteries and supply electricity for vehicle electrical systems such as lighting, wipers, air conditioning, heater motor, car audio , etc.
Vehicle alternators generate AC (Alternating current ) converted to DC (direct current) by the alternator rectifier (diode pack)
The term Vehicle Rotating Electrics refers to Alternators, Dynamos, Starter Motors, and D.C. Motors
The Alternator is generally engine driven by drive belt connected to the crankshaft pulley , or coupling to shaft drive or gear drive.
If drive belt driven correct belt tension is essential.
The alternator must be mounted securely to enable it to be driven efficiently. Broken or loose mounting brackets can result in loss of drive belt tension and subsequent loss of alternator charging performance.
Specialist applications may require a higher output alternator upgrade when additional accessory loads are fitted or multiple batteries are employed
OE vehicle manufacturers calculate the power output of the alternator required for each vehicle with
regard to circuit loading and original equipment provision.
Increasing the load and power generation requirements of a vehicle electrical system may require higher capacity alternator and charging system upgrade including cable.
Special purpose vehicles with split charge dual or more auxilliary battery systems may be fitted with an additional alternator or battery charging management system.
Certain vehicles have both 12 volt and 24 volt alternators.
High output heavy duty brushless alternators found on heavy commercial vehicles, buses, and military equipment benefit from extended lifespan due to lack of brushgear.
Alternators generate electrical power as alternating current (a.c.) by creating a magnetic field in a rotor.
As the alternator rotor spins the magnetic field rotates. Wires forming the stator housing cut the magnetic field to generate a.c. output.
A.C needs to be converted to direct current to allow the vehicle battery to be charged. A.C. to D.C. conversion is done using the diode pack.
Alternator output is regulated by control of the input excitation field of the rotor by a voltage regulator.
Early signs of alternator or charging system fault may be indicated to the driver by illumination
of the instrument panel alternator or battery charge warning light.
Gradual loss of vehicle electrical power may result until the engine cuts out and fails.
Low battery voltage may mean the starter motor clicks or does not operate preventing the vehicle engine from being started causing breakdown.
Battery light staying on ? Have the vehicle battery and vehicle electrical charging system tested. A visual check with the engine stopped should be carried out to ensure the alternator is secure and drive belt correctly tensioned. Also check for oil ,fuel or coolant leaks which may have caused the alternator to fail.
The battery charging light may illuminate if the alternator is not charging or if a wiring fault exists.
A wiring fault such as a broken wire may cause loss of power, ground, or signal at one of the alternator multiplug terminals
Fuseboard, relay plate, or ecu connection problems may also cause the battery charging system to fail.
Check all connections are tight and wires are in good condition.
Check all fuses are intact. A blown fuse may indicate a short circuit or current over loading requiring further investigation and repair.
Check all alternator heat shields are in place .
A multimeter can be used to quickly test or diagnose a failed alternator.
Measure battery voltage with the engine off using a multimeter set to dc volts range.
Start the engine and run at around 2000rpm whilst monitoring battery voltage reading which should have increased slightly if the alternator is charging the battery.
Incorrect alternator output voltage ( alternator overcharging or undercharging ) can affect sensitive vehicle computer systems and related systems.
Typical battery voltage for a 12 volt system would be :
Potential causes of excess Alternator noise
Excessive drive belt tension.
Insufficient drive belt tension may cause a squealing noise.
Stator winding fault causing phase imbalance.
Noisy one way clutch pulley (chatter) may indicate that the drive pulley needs renewal.
Alternator one way clutch over run pulleys are available seperately but may require special tools to fit.
Water leaks on to the alternator : Water entering an air cooled alternator can cause problems particularly in Winter when at freezing temperatures the water turns to ice causing internal component damage .
An incorrect battery specification may cause charging system problems where a vehicle alternator function is controlled by an electronic control unit (ecu). Some vehicles have computerised battery management systems (BMS).
Expected lifespan of many vehicle alternators is 100,000 to 200,000 miles, dependant upon operating conditions
such as environment, temperature, driving cycle, maintenance, component age, etc.
Many alternator core units can be reconditioned, remanufactured , repaired, or recycled.
Premature alternator failure may be caused by power surge , overload or misuse.
Alternator translated : Alternateur Alternador Alternatore Dynamo Generatoren Lichtmaschine 发电机 алтернатор
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