Electrics & Electronics: Charging, Starting & Lighting

Charging	Charging system	The charging system allows for a means to re-charge the battery and allow for electrical usage of components in the vehicle.
	Alternator principles	In the alternator a magnetic field rotates and the conductors are stationary. Mechanical energy is converted to electrical energy by electromagnetic induction.
	Alternating current	The value of the induced EMF depends on the strength of the magnetic field, the speed at which the magnet rotates and the number of turns of wire on the stationary coil.
	Alternator components	The maximum current that can be delivered by the alternator is designed during manufacture and so the alternator does not require a current regulator.
	Rectification	Automotive alternators use a 3 phase bridge rectifier that has 3 positive diodes and 3 negative diodes to rectify the AC current in the 3 phase stator windings to produce a DC output.
	Phase winding connections	Two methods of connection can be used for the stator. Star or wye connection and delta connection.
	Rotor circuit	When the ignition is first switched o current flows through the charge indication lamp, the rotor windings and voltage regulator to ground. Current flow through the rotor winding is controlled by the voltage regulator when the engine is running.
	Voltage regulation	The regulator switches rapidly between the ‘on’ and ‘off’ conditions, to allow the alternator to maintain an output voltage of approximately 14 volts.
	System operating voltage	The maximum current output of the alternator at system operating voltage is designed during manufacture.
	High voltage charging systems	To meet the increased demand from such high usage systems as electric drives, higher voltage batteries and packs with an appropriately high voltage charging system are necessary.

Alternator construction	Rotor	The rotor is an electro magnet. It consists of a coil of wire wound around an iron core and is pressed on to a steel shaft. It usually has 8 to 12 tapered pole projections.
	Stator	The stator consists of a cylindrical laminated iron core, which carries the 3 phase winding in slots on the outside.
	Alternator end frames	The end frames of an alternator are made from aluminium.
	Slip ring & brush assembly	Slip rings are normally copper bands connected to the rotor winding. Brushes allow a connection to the rotating rotor winding.
	Rectifier assembly	Diodes are mounted on heat sinks. The positive heat sink is insulated from the frame, the negative heat sink is connected to the frame.
	Alternator cooling fan	The fan is a centrifugal type that is mounted on the rotor shaft or drive pulley.

Charging procedures	Checking a charging system	Always follow any manufacturer's personal safety instructions to prevent damage to the vehicle you are servicing.
	Removing & replacing an alternator	The alternator must not be operated with the battery disconnected or the terminals at the back of the alternator disconnected.
	Inspecting & adjusting an engine drive belt	A belt that has been soaked in oil will not grip properly on the pulleys and will slip. If the oil contamination is severe enough for this to happen, replace the belt.
	Replacing an engine drive belt	If you don't have a tension gauge, you can estimate the tension by pushing the belt inwards with your hand.

Starting	Starting system	The starting system consists of battery, cables, starter motor, flywheel ring- gear and the ignition switch.
	Starter motor principles	The starter motor converts electrical energy to mechanical energy and is mounted on the cylinder block in a position to engage a ring gear on the engine flywheel.
	Starter motor construction	The armature is the revolving component of the direct current motor. Brushes maintain contact with a commutator on the armature shaft to conduct current through the windings as the armature rotates.
	Starter magnet types	Normally four stationary field poles are mounted in the outer casing or yoke and these can be electro-magnets or permanent magnets.
	Starter motor engagement	Solenoid operation moves the operating fork and pinion to mesh with the ring gear and causes the plunger contacts to bridge the main starter terminals.
	Commutation	A starter motor armature has a large number of conductor loops and so has many segments to the commutator. Each segment is connected to a loop and is insulated from other segments.
	Switching	The starter motor is brought into operation by a starter switch incorporated as a part of the ignition key. It operates a solenoid which has two functions. To engage the drive pinion with the engine flywheel and connect the battery directly to the starter motor.

Starting procedures	Checking a starting system	Always follow any manufacturer's personal safety instructions to prevent damage to the vehicle you are servicing.
	Jump-starting a vehicle	Make sure the battery is not frozen; you cannot jump-start a frozen battery.

Lighting	Lighting system	The lighting system provides a means of allowing the driver to both see when driving in poor visibility conditions and to provide a means of signaling to other drivers.
	Light bulbs	A lamp consists of a fine coil of tungsten wire, called a filament, enclosed in a clear glass envelope from which all has been removed.
	Bulb information	All bulbs have letters or numbers which indicate the power consumed by the bulb in operation and the nominal operating voltage.
	LED lighting	An LED is a special type of semiconductor diode. Like a normal diode, it consists of a chip of semiconducting material impregnated, or doped, with impurities to create a structure called a p-n junction.

Types of lights	Stop lights	Stop lights are red lights fitted to the rear of the vehicle which are activated whenever the drive operates the foot brake to slow or stop the vehicle.
	Reverse lights	Reversing lights are white lights fitted to the rear of a vehicle. They provide vision behind the vehicle and warn other drivers that the vehicle will move backwards.
	Indicators	Indicators are amber lights located at the corners of the vehicle. They are pulsing lights that warn other road users of an intended change in direction.
	Headlights	In headlight bulbs the main bean filament is positioned at the focal point of the reflector, and the dip beam filament is placed above and slightly to one side.
	High intensity discharge (HID) lights	HID lights produce light by striking an electrical arc across tungsten electrodes housed inside a specially designed inner fused quartz or fused alumina tube.
	Driving lights	Driving lights are used to supplement vehicle headlight systems.
	Fog lights	Fog lights are used with other vehicle lighting in poor weather such as thick fog, driving rain or blowing snow.
	Cornering lights	Cornering lights are white colored lights usually fitted into the bumper bar and are designed to provide side light when the vehicle is turning corners.
	Smart lighting	Different lighting technologies can be fitted individually or together to form comprehensive adaptive lighting systems.

Lighting circuits	Park & tail light circuits	Red tail lamps and white park lamps are low wattage lamps that allow the vehicle to be seen by other road users. They are connected in parallel.
	Headlight & dip circuits	Dip or low beam is used in built-up areas or when the driver of an approaching vehicle could be dazzled by the main beam.
	Circuit diagrams	Circuit diagrams contain information about wire size, wire color, earth locations and shape and location of electrical connectors around the vehicle.
	Networking & multiplexing	A multiplex network reduces the number of wires in the wiring harness and greater vehicle content flexibility.

Lighting procedures	Checking lighting & peripheral systems	A vehicle may have warning lights that will activate only if that circuit is in use. You may need to turn that circuit on to see the warning light.
	Checking & changing an exterior light bulb	Make sure that the fuses are in good condition before attempting to change a bulb in a circuit that has more than one bulb, such as the turn signal circuit.
	Checking & changing a headlight bulb	Always make sure that you replace a bulb with one of exactly the same type. Otherwise, change both lights at once, so they always show the same intensity in lumens.
	Aiming headlights	Some manufacturers may suggest that the headlights be aimed on high beam, others on low or dipped beam, depending on the number of lights and type of application.