The Ultimate Alternator Buying Guide

The Complete Buying Guide For Alternators

As automotive technology is advancing, there is a need for more electrical power. This demand is fulfilled by the alternator that converts the engine's mechanical energy into electrical power. An alternator is one of the major components that help in vehicle starting and charging systems. The alternator works to keep the battery charged when the vehicle is running and powers the electrical systems in the car like the interior and exterior lights, and the instrument panel, windows, etc. Therefore, it is necessary to maintain the alternator in the best condition. This guide helps you buy the right alternator for your vehicle and needs. 

Our Top Picks For Alternators

Table Of Contents

1. What Is An Alternator?

An alternator in the automobile charges the battery and supplies power to the electrical components when the engine is running. It directly or indirectly affects the operation of various systems in an automobile.

When the spark plug ignites the engine, the alternator takes over the battery's power supply and continuously charges the battery and vehicle's electronic components while the engine is running. In most vehicles, the battery's voltage is 12 Volts, whereas the alternator output is between 13 to 14.8 volts.

The alternator works on the principle of electromagnetic induction and converts the rotational energy from the engine to electrical energy stored in the battery. The electricity channelled is carried through the copper wires to a rectifier diode, which converts the AC power into DC. The voltage regulator acts as a guard to control the excess voltage flow to power the battery, limiting the battery overcharging and burning. This cycle continues, as the battery is discharged and the current is passed back into it from the alternator.

The alternators are situated in front of the engine and are driven by the serpentine belt. The main components of the alternator are a rotor and stator, diode rectifier, voltage regulator, and a cooling fan. 

A high-performance alternator is an ideal solution to keep the vehicle in good condition and provide enough power to the electrical components.

2. What Are The Types Of Alternators?

2.1 According to Electrical Output

2.1 According to Electrical Output

A. High-Output Alternators

High output alternators produce maximum charging power and provide power to the electrical systems where high amperage capacity is required. Without much effort, many high output alternators produce up to 200 amps without affecting the battery charging capacity. These alternators are designed with brushless technology ensuring low maintenance, high durability, and a longer life span. 

Modern cars hold advanced audio systems that require high amps which can be obtained from high output alternators. Alternators that produce between 130 and 220 amps are ideal for high-end audio systems. Higher output alternators will also operate the other demanding electrical accessories on an engine.

B. Regular Alternators

Regular alternators use carbon brushes and are heavy compared to high output alternators. They have a shorter life and produce a low voltage at high speeds. The brushes wear out quickly compared to high-output alternators and can lead to overheating. However, they are capable of powering the electrical and other accessories of a vehicle, and they come standard in most vehicles.

2.2 New Vs Remanufactured Alternators

2.2 New Vs Remanufactured Alternators

When the alternator of your vehicle fails, you have the option of choosing between a new alternator or a remanufactured one. 

The new alternators are designed and manufactured to match OE (original equipment) specifications. It consists of all the new parts with no wear and tear and is usually the most expensive option.

A remanufactured alternator is one that has undergone a major teardown and inspection, and all the worn-out components are replaced with new ones. Remanufacturing alternator is an industry practice that involves the replacement of old components and testing to meet the OE specifications. Remanufactured alternators offer the same performance, durability, and service as the new ones. They are cheap compared to new alternators and are also available with warranties from reputed brands. 

2.3 Alternators Vs Generators

2.3 Alternators Vs Generators

The alternator and a generator are different in a number of ways. First, an alternator produces an AC current, whereas the generator produces a DC current. Second, the structure of the generator differs from that of an alternator and each produces a different amount of current. Alternators comprise three different coils that give them more electrical power as compared to generators that have a single coil of wire.

Furthermore, alternators are compact and generate higher voltages and more current at lower speeds as compared to generators. For these reasons, alternators are preferred as power-generating units in vehicles.

3. What Factors Do I Need To Consider Before Purchasing An Alternator?

3.1 Compatibility

3.1 Compatibility

Alternators vary in size and appearance. Analyze the size and fitment of the alternator you want to fit into the car. If you are replacing a high output alternator with a remanufactured unit of the same size, it is essential to check the dimensions and mounting location in your vehicle. Some cars hold regulators mounted externally to the alternator body that may cause a difference in amperage usage. Alternator size may also increase the set amperage. External cooling or some time water cooling are required for large-sized and high output alternators.

Compatibility depends on the engine model, year, and compartment layout.

3.2 Electrical Load

3.2 Electrical Load

Choosing the right alternator comes down to the vehicle's total electrical load. Look for the alternator with the same or more amps to extend the life of the alternator. A high amp alternator can put a lot of stress on the drive belt, for that you need to limit the alternator size to the drive belt’s capacity. Ideally, the alternator output should be 50% greater than the vehicle's electrical load. High-output alternators are used in high-performance automobiles, off-road automobiles, and heavy-duty vehicles. High output alternators on large vehicles can use between 200 to 350 amps. Smaller cars may use about 100 amps with batteries that run at about 12 volts. These alternators dissipate heat evenly and do not become too hot.

Loads on the electrical system will be high when the engine is at idle. The engine cooling fans and other electrical accessories require more power at an idle state. When choosing an alternator, ensure that it can output the required amperage at idle to meet the demands of all the electrical components. 

3.3 Upgrading The Alternator

Before upgrading an alternator to high output or installing a high output alternator, make sure that the vehicle is capable of handling the larger amperage load. To upgrade an alternator from a standard output alternator to a higher output alternator, modify the gauge of the charge wire. The charge wire is the wiring that carries power from the alternator to the battery and passes through other electrical components. It is highly recommended to upgrade the charge wire size if upgrading to a high output alternator to avoid wiring burnout. High output alternators do not harm the electrical components or charging system if the amperage is increased.

4. What Are The Best Alternator Brands For My Vehicle?

4.1 Wilson Alternators

4.1 Wilson Alternators

Established in 1940, Wilson Auto Electric is the largest independent North American manufacturer and re-manufacturer of alternators, starters, generators, and electrical component parts for the automotive, agricultural, industrial, heavy-duty truck, and marine aftermarkets.

New Alternator Part Numbers: 90-01-4415n, 90-29-5747n, 90-01-4646n, 90-01-4246n, 90-01-3106n, and more.



  • The most extensive rotating electrical product offering in the industry.
  • Manufactured to OEM specifications or better.
  • The highest quality and lowest warranty rate in the industry based on customer feedback.
  • Designed for customers who ask for more reliability and performance.
  • Every new alternator is tested prior to its departure from the manufacturing unit.


Remanufactured Alternator

Remanufactured Alternators part Number:  90-29-5719, 90-02-5076, 90-01-4415, 90-01-4705, 90-02-5153, and more. 



  • Remanufactured alternators are assembled with sorted, tested, gauged, and replaced to OE quality specifications and new main parts.
  • Easy to install and provides excellent cranking performance.
  • Widely tested to meet all reliability demands for all types of vehicle applications.
  • Provides performance, quality, and reliability at new alternators at lower prices to avoid servicing frequently.
  • Completely tested at low and high speeds.
  • Re-engineered for exact-fit to improve vehicle performance.
  • The output is assured to meet or exceed OE specifications. 

For more information and a detailed product line, visit the Wilson Alternator Section.

4.2. Remy Alternators

4.2. Remy Alternators

Remy® is a worldwide leader in manufacturing starters, alternators, and electrical components for the automotive, heavy-duty, and transportation industries. Remy alternators are of premium quality, excellent efficiency, and cost-effective for off-road and commercial vehicles.

New Alternator 

Part Numbers: 91334, 92535, 94615, 91653, 94744, and more.


  • Designed to meet or exceed OE standards.
  • Effort-less and quick to install.
  • Ensures that the unit fits, works, and provides an exact replacement to the original unit.
  • Improves fuel economy of the vehicle and battery charge time.
  • Holds less weight and compact to fit in the space.
  • Less noise while operating due to fewer moving parts.
  • Manufactured from high-quality materials to provide longer life.

Remanufactured Alternator

Part Numbers: 11070, 11159, 11065, 23008, 11002, and more.


  • Provides outstanding performance similar to new alternators.
  • Vigorously tested as per OE specifications.
  • Uses less engine power and offers increased fuel efficiency.
  • High durability, less wear, and longer life.
  • Offers medium and heavy-duty applications with excellent output power
  • Excellent mounting configurations


For more information and a detailed product line, visit the Remy Alternator section.

4.3 Armature DNS Alternators

4.3 Armature DNS Alternators

Since 1977, Armatures DNS 2000 Inc. has demonstrated strength and stability as a leader in remanufactured alternators, starters, brake calipers and water pumps. DNS takes pride in ensuring that every product leaving its door has passed a thorough inspection. The steps taken include using the best raw materials available in the industry and testing each finished product with state-of-the-art testing equipment.

New Alternators 

Part Numbers: na08292


  • Tested at various stages to ensure high standards that meet and exceed OE specifications
  • Flexible in all types of weather conditions
  • Provides greatest strength and stability
  • Excellent compatibility

Remanufactured Alternators

Part Numbers: a11445, a11793, a11534, a11629, a11065, and more.


  • Provide good OE fit, form, and function as combined with the latest remanufacturing and testing technology
  • 100% factory tested and manufactured for maximum performance.
  • Manufactured to quality standards for long-term reliability.
  • Superb cranking performance

For more information and a detailed product line, visit the Armature DNS Alternator section. 

4.4 Denso Alternators

4.4 Denso Alternators

Quality, Reliability, and Value. At DENSO we've taken everything we have learned as an OE manufacturer and applied it to our aftermarket product lines. Every component that leaves our factories has been designed with precision, manufactured to OE standards, and subjected to rigorous safety and performance tests.

Part Numbers: 210-0750, 210-0766, 210-0657, 210-5350, 210-0580 and more.



  • Excellent quality fit, appearance, and service life that meet and exceed OE specifications.
  • Maximum efficiency: smallest and lightest in the world for their output.
  • Designed to perform in cold and hot weather conditions.
  • Maximum cranking torque under all conditions.
  • Fully compatible with sophisticated electronics systems.
  • Rigorous manufacturing and testing technology meet the highest standards of performance.
  • The primary choice of the aftermarket for a trouble-free repair.
  • Improves the magnetic circuit to increase output with the optimized stator and rotor size.
  • Allows faster rotor due to smaller pulley diameter.
  • Reduced fan noise, size, and weight.


For more information and a detailed product line, visit the Denso Alternator section.

5. What Are The Symptoms That My Alternator Is Bad?

Alternators tend to cease after running for a long duration. They show symptoms of faulty behavior that need timely attention for required action.

A. Warning Light 

Alternators tend to wear out after continuous service after a long run. The first indication of a faulty alternator is either a battery symbol or ‘ALT’ / ‘GEN’ light illumination on the vehicle's dashboard.

A faulty alternator will interrupt the electric current to the different components of the vehicle. The alternator components receive less voltage or high voltage, causing dimming or brightening of the headlights due to faulty or loose connections in the alternator. The vehicle's computer system detects the fault, causing the ALT or GEN warning sign to light up on the dashboard.

B. Rattling Or Clicking Noise Under The Hood

Growling, and whining coming from under the hood due to a loose accessory or a serpentine belt, bad bushings, or bearing in the connection between the crankshaft and the alternator. 

C. Engine Trouble 

A faulty alternator decreases electricity supply resulting in rough idling, misfiring, bad start, hard starting, poor acceleration, and abnormal engine behavior. During cold weather conditions and uneven terrains, the engine may experience a hard time starting due to reduced power from the faulty alternator.

D. Discharged Battery

Repeated discharging of the battery can also be due to a faulty alternator. A bad alternator cannot recharge the battery to its full capacity. Some issues in the electric connections also cause voltage drain out in the battery. It is the first indication for an engine that cannot start, and you may need to replace the battery or an alternator.

E. Bad Smell From The Hood

You may notice a bad smell when the pulley belt heats up excessively due to improperly placed belts generating too much friction. A hindered drive belt can also be the reason for the bad smell. 


F. Failing Of Electrical Accessories

Windows taking more time to roll up or down, failed power locks, car radio performing intermittently, and heated seats not working are other indications that the alternator is dying.

6. FAQs

Q. How much does it cost to replace an alternator? 

The cost to replace an alternator depends mainly upon the car model and year of make and its brand. The cost of an alternator ranges between $95 to $490. You can add a labor charge for installation which varies from area to area and mechanic to mechanic.

Q. Do Alternators Come With A Pulley Installed? 

Few alternators come with a pulley, and some don't. If you have ordered with a pulley, it needs to be compatible with the drive belt in your vehicle to avoid pulley spinning issues after installing a new alternator.

Q. How long does an alternator last? 

An alternator lasts for 160000 to 240000 km.  Usually, mechanics inform you ahead of the mileage lower than 160000 for safety. It is always good to be on the safer side with the signs of wear and damage so that you can either repair or replace them on time. 

Q. Is It Good Or Bad To Buy A Remanufactured Alternator?

Remanufactured alternators work well and last long just like new alternators. Both are decent options to choose from but if the budget allows, you should always go for a new alternator. Remanufactured alternators save you a lot of money, last very long, and are offered by reputed brands.

Q. Can You Drive A Vehicle With A Bad Alternator?

You can drive the vehicle for shorter distances with a bad alternator, only if it can provide power to the spark plugs to start the engine. If the alternator is going bad, it cannot sufficiently recharge the battery and put more load on the engine and electrical systems. Until the battery drains completely, a vehicle can operate till the alternator ceases.

Q. How Can I Detect A Faulty Alternator?

Another way is to start the vehicle or jump-start the vehicle and note the output voltage of the alternator with a digital multimeter. If the multimeter reads 12V or less, that means the alternator is going bad. If the voltage reading is within the 13.5 and 14.8 volts range, then the alternator is in good working condition.

Q. What Causes An Alternator Failure?

Dust or dirt accumulated in the windings during its service, worn-out shaft bearings, broken pulley or drive belts, belt slippage, disconnected ground cable, damaged or worn-out wiring, fuse blow out due to power surge, current leakage from rectifier diodes, and dying battery are all possible reasons of an alternator failure.

Q. How Long Will A Battery Last With A Dead Alternator?

Depending on the capacity of the battery, you can drive the vehicle for some time. When an engine is idling, if the charging voltage is less than 13.5 volts, there is a charging system problem that is caused due to a bad alternator.

It is difficult to assess how long a battery can run with a dead alternator as it depends on the situation and the electrical load. Technically it can run for a short distance as long as the battery power supports the vehicle starting system

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