installationAutoelectrical Installation
alternator4x4 ALTERNATORS

UK Suppliers of Alternators

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Supplier of 12v or 24v automotive alternators brand new outright with a full 12 month warranty*
or factory service exchange alternators rebuilt to manufacturers specification carrying manufacturer standard warranty*
Alternator repairs and component parts supplied

OE or Aftermarket Alternators

Replacing :
ADL Bosch Butec CAV Delco Ducellier Hitachi Iskra Lucas Magnetti Marelli Magneton Mando Motorcraft Motorola Mitsubishi Melco Nikko Nippon Denso Paris Rhone Prestolite Unipoint Valeo Visteon. (oe names used for reference purposes only)

Alternator Testing

Diagnostic facilities to test many makes and models of vehicle alternators for charging output on the vehicle or by free run bench test.
Services include strip, test, repair and rebuild of vehicle alternators to component level.

Alternator Repair Service Shropshire

Cost effective specialist alternator repairs may include bench test or strip and test of individual alternator components then replacement such as fitting of a diode pack, bearings or voltage regulator to get your old alternator working again or fitting of a complete brand new or service exchange unit.

Alternator repair prices

Repair of your existing alternator can offer a cheaper solution than replacing a complete unit where minor components have failed.
Many alternators fitting classic vehicles can be hard to obtain so repair may be the only option.
To purchase a complete alternator as aftermarket spare parts would be much more expensive than a mass produced factory built unit.
Minimum repair cost is normally above £50 taking account of labour.

Alternator Parts Supply

Supply of brand new oe and aftermarket alternator rebuild parts including diode rectifier pack - voltage regulator - bearings - rotor - stator - slip rings - casings - fasteners . Pleae note, alternator oe part numbers are required to source components. Many alternator parts can be sourced for next working day subject to time of order.

Alternator Fitting in Shropshire and Mid Wales

We can provide a mobile callout service for vehicle breakdown repairs including alternator supply & fitting on site where access allows subject to engineer availability in
Shrewsbury & Local Shropshire areas.

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

Alternator FAQ list

Common Alternator Wiring Terminal Letter Designations

Vehicle Alternator Function :

The automotive alternator is an electricity generation plant which provides power to recharge one or more vehicle batteries as well as supplying electricity for vehicle electrical systems such as lighting, wipers, heater motor, car audio ,sat nav, etc whilst the vehicle engine is running.

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.

Alternator lifespan -

Alternator lifespan of a motor car alternator is 100,000 to 200,000 miles, dependant upon operating conditions such as environment, temperature, driving cycle, maintenance, etc.

High Output Alternator

A higher output alternator may be required when additional accessories are fitted or a secondary battery is fitted

The vehicle manufacturer calculates the power output of the alternator required for each vehicle with regard to original equipment fitment. Increasing the load on a vehicles electrical system may require an alternator system upgrade including cable. Special purpose vehicles with split charge dual battery systems may be fitted with an additional alternator or battery charging management system.

How Alternators Work

Symptoms of a faulty alternator

The first sign of an alternator or charging system fault is often indicated to the driver by illumination of the instrument panel battery charge warning light whilst the engine is running followed by gradual loss of electrical power 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 .


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. Check all connections are tight and wires are in good condition. Check all heat shields are in place .
A quick test to diagnose a failed alternator is to 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 :

  • Engine off  : 12.5 volts
  • Engine running at 2000 rpm : 13.2 to 14.6 volts at battery(regulated voltage)
  • A battery voltage indicated above 15 volts with the engine running on vehicles with a standard 12v charging system often indicates a fault though vehicle manufacturers specification should be checked to verify because certain vehicle alternators may regulate charge at higher levels .
  • Some modern vehicles have alternators with dynamic electronically controlled output which is affected by the embedded software in the vehicle engine control computer. These require special equipment to test and verify as output varies according to demand.

Alternator Noisy ? Potential causes of excess Alternator noise

Excess drive belt tension
Insufficient drive belt tension may cause a squealing noise.
Bearing failure
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.

Battery Charge Warning Lamp On ? Flat battery ? Alternator not charging ?

Common causes of alternator failure are:
Broken or defective wiring to the alternator. May cause battery warning light to either stay off or stay on permanent.
Wear and tear ; Worn out brushes ,sliprings, bearing failure,
Alternator Component failure eg blown diodes , diode pack failure, voltage regulator failure, broken windings.
Excessive drive belt tension causing premature bearing failure.
Insecure mounting bolts / bracket causing insufficient drive belt tension.
Poor electrical connection causing high resistance and leading to overheating.
Electrical overload due to a defective battery or fitment of vehicle accessories, or vehicle wiring faults.
Inadequate ventilation and cooling. Dusty working conditions (particularly for tractors combines and construction plant working in agricultural and site environments) can cause dirt and dust to be sucked in to the alternator by the alternator cooling fan, a build up of dust can block airflow causing overheating of components such as diodes and electrical windings, resulting in breakdown.
Voltage surge caused by boost starting using jump leads without surge protection. (Diode failure)
Oil, fuel or coolant leaks onto the alternator.

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 .

On modern alternators controlled by an electronic control unit an incorrect battery type may cause problems.

Alternator translated : Alternateur Alternador Alternatore Dynamo Generatoren Lichtmaschine 发电机 алтернатор