Alternator in the automobile generates alternating current (AC) voltage then converts this AC electricity into direct current (DC) voltage. The auto alternator, not the automotive battery, is responsible for providing electricity to a car, truck, van, Sport-Utility Vehicle and minivan.
Alternator history. What is an alternator? Why have an alternator? What is the difference between an alternator and a generator? How does an alternator produce Direct Current (DC) voltage needed by a car, truck, van, Sport Utility Vehicle, motorcycle, minivan and all-terrain vehicle (ATV)? Answers to these automobile alternator questions and other automotive alternator information can be found on this auto alternator web page.
Alternator, Alternator Voltage Regulator, and Alternator Diode at 1 Auto Accessory Internet Automobile.
Alternator, generator, alternator rebuild kit, alternator replacement, alternator diode, and alternator voltage regulator replacement and repair.
Alternator - What is an Alternator? An alternator is a device for converting mechanical energy into electrical energy in the form of alternating current (AC) voltage. In the case of an automobile alternator, this alternating current voltage is further converted to direct current (DC) voltage. DC voltage is utilized to recharge the automobile battery, provide electrical power to auto ignition systems, automotive blower motors, and other "high drain" electrical motors that function ONLY when the automobile engine is operating. Many auto owners are under the misconception that the automobile battery provides all the electricity demanded by their auto.
Alternator History or History of Alternator. The original 6 volt generator charging system, generating 6 volts of Direct Current (DC) voltage for charging the starting motor battery and providing electricity to the ignition system, was sufficient for the small automobile engines of the time. Larger automobile engines required a larger starting motor, thus a 12 volt generator charging system, generating 12 volts of Direct Current (DC) voltage for charging the starting motor battery was created for these larger automobile engines and providing electricity for the ignition systems. 12 volt charging systems are currently the standard for the consumer automobile industry even though it did have issues. 12 volt generators will only produce 12 volts when the automobile engine is operated at a specific speed.
Alternator Did Replace the Generator. Below a specific engine speed or Revolutions Per Minute (RPM) the generator will not produce the required 12 volts of direct current voltage needed to charge the battery, operate the electrical and ignition systems. Operating an automobile generator above this specified engine speed causes too much voltage to be generated. Should this high voltage not be controlled by a voltage regulator it will cause serious damage to the automobile electrical system and ignition system. Alternator, on the other hand, produces the minimum amount of voltage it was designed for, regardless of the automobile engine speed. Alternator internal components include a solid state device called an "exciter" which increases the alternator output voltage whenever called upon by a high drain device like a heater blower motor or windshield wiper motor. However this voltage is alternating current (AC) which is unacceptable for use in automotive applications.
Alternator Output Modified for Direct Current Applications. Alternator alternating current produced by an auto alternator is passed through a semiconductor device called a rectifier diode where alternator alternating current voltage is converted to direct current voltage. Without getting too technical, the rectifier diode housed within an automobile alternator, is a two terminal solid state switch converting sine-wave current (AC) into unidirectional current (DC).
Alternator Problem. Alternator may become noisy while the engine is running which is an indication the alternator shaft bearing or bearings are failing. This is a common problem caused by excessive tension on the drive belt on the alternator pulley attached to the alternator shaft. Alternator may, due to excessive moisture, overheating or dirt, develop a short or open in its windings. Alternator diodes may develop a condition known as "short to ground". This results when the automobile alternator was inadvertently sprayed in a car wash as part of the automobile engine cleaning process. Finally the rectifier diode can become damaged, rarely, when the automobile undergoes a process called "resistance welding" during exhaust replacement or auto body sheet metal replacement and the negative auto battery cable was not disconnected.
Alternator Problem - No Alternator Voltage Output. No alternator voltage output can be the result of a broken alternator drive belt from the engine crankshaft pulley to the alternator drive shaft pulley. After the Alternating Current (AC) is developed, by the operating alternator, it passes through a rectifier diode to be converted to Direct Current (DC). A shorted rectifier diode or rectifier diodes condition will prevent this process thus no alternator voltage output will result. An open rectifier diode or rectifier diodes condition will also prevent this process. Alternator rectifier diode or alternator rectifier diodes replacements can be purchased individually or as part of an alternator rebuilt kit. Faulty alternator windings, although rare, can also cause no alternator voltage output. After the alternator AC has been converted to DC voltage it is sent to either an internal voltage regulator or external voltage regulator, depending on automobile manufacturer.
Alternator Problem - Erratic Alternator Voltage Output. Erratic alternator output voltage can be the result of a loose alternator drive belt from the engine crankshaft pulley and alternator drive shaft pulley or faulty alternator voltage regulator. The purpose of the voltage regulator is to constantly maintain the DC voltage and current output developed by the automobile alternator. The alternator voltage regulator provides a means to meet all the electrical demands of the electrical system and recharge the electric starter motor battery. When operating properly the excess alternator voltage output and current are discarded by a path to the automobile chassis ground. This path is also where the negative battery terminal post is connected. The alternator voltage regulator is designed to operate within a specified limit. Exceeding the maximum alternator voltage regulator specified limit, by adding any high current drain electronic accessory, will cause the alternator voltage regulator to stop functioning. Internal alternator voltage regulator and external alternator voltage regulator replacements can be purchased individually or as part of an alternator rebuilt kit.
Alternator Problem - High Alternator Voltage Output. High alternator voltage output is a problem associated with older model vehicles and vehicles equipped with an external voltage regulator. These external voltage regulators utilize "points" which mechanically open and close to regulate the voltage developed by an alternator which in turn is supplies the the electrical system. When the points open, or disconnect, the voltage developed by the alternator is sent to ground. When the points close, or connect, the alternator voltage is sent to charge the battery and supply electricity to the automobile electrical system. Alternator voltage regulator points at one time were adjustable. This means that by adjusting the air gap between the points one could increase or decrease the alternator voltage output to the automobile electrical system. Alternator voltage regulator points operate like distributor points and experience the same problems of pitting, burning and corrosion. These problems, over time, result in changing the specified air gap settings for the alternator voltage regulator to perform properly. An external voltage regulator is a silver or black metal box attached somewhere to the vehicle firewall under the hood with a small visible ground strap. How to locate an external alternator voltage regulator: Locate the vehicle alternator by following the crankshaft drive belt(s). Locate the largest diameter wire connected to the alternator. Follow this large diameter wire from the alternator as it snakes it's way to the alternator voltage regulator. This large alternator wire will only be connected to the alternator voltage regulator.
Alternator Rebuild Kit or Alternator Replacement Considerations. Depending on how adventurous the do-it-yourself automotive owner is, alternator repair, utilizing an alternator rebuild kit, can be accomplished. As a minimum an alternator rebuild kit will contain the needed replacement alternator rectifier diode or alternator rectifier diodes. Rebuild kits, while cheaper than complete alternator replacement requires the do-it-yourself auto owner or mechanic to disconnect the negative battery cable, disconnect electrical leads, remove the drive belt, unbolt the alternator from the engine and any brackets, mark the position of the alternator housings, "crack open" the alternator housing, replace the alternator defective parts, align the marks on the alternator housing, torque alternator housing bolts to specifications, bolt alternator to engine, bolt alternator to brackets, re-tension the drive belt or belts to specifications, reconnect alternator electrical leads and reconnect the negative battery cable.
Alternator replacement on the other hand does not involve the added work of alternator internal parts replacement, however the do-it-yourself auto owner or mechanic must insure that the new alternator pulley is included on the replacement alternator drive shaft and that the alternator pulley is the same design as the alternator pulley on the defective alternator. Alternator replacement can be performed in less than an hour by the average do-it-yourself "shade-tree-mechanic" or computer IT professional on any car, van, truck, sport-utility-vehicle and minivan.
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