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You may not realize it, but the alternator is a fairly important part of your vehicle’s electrical system. It generates the power that your car or truck needs to operate and works alongside the battery to provide an electrical current that recharges the battery and provides power to a variety of things, including the ignition, radio, and heating and air conditioning.
There are some telltale signs that indicate your alternator is malfunctioning. For example, if your lights are dim, it’s probably time to replace the alternator. Our buying guide below will help you find the top alternators on the market and give tips to follow when you’re replacing one.
The Best Alternator
This 12-volt, 145-amp with internal regulator alternator is intended for certain makes of the following vehicles: Buick Rainier (2007), Cadillac Escalade (2006), Chevrolet Avalanche (2005-06), C/K/R/V series pickups (2005-07), Trailblazer (2007-08), Envoy (2007-09), Hummer H2 (2007), Saab 9-7X (2007-09). The alternator is the same one you would buy in store for half the price. It’s a very good alternator, fits perfectly, and works great. It’s also easy to install, and it charges very well.
However, there have been some complaints about the product, particularly when it comes to shipping. The alternator may come apart during shipping, and the box may be damaged before it makes it to your home or business. There has also been a complaint that the alternator caused a parasitic load.
Matched against OE originals for performance
Heavy-duty rectifiers and top-quality bearings
- BrandDB Electrical
- Weight15 pounds
Fits perfectly and works great
Easy to install
May be damaged during shipping
In rare circumstances, it may cause a parasitic load
This 12-volt, 117-amp alternator is for a 2001 4-liter Jeep Cherokee. It’s designed to meet OEM specifications. It runs great, has great voltage, and is an exact fit. Customer service is very helpful if you have any technical questions about the product. The alternator is packaged well and comes with all the associated hardware. Also, no core return is required, so you don’t have to pay a deposit charge and shipping.
However, there has been a complaint that the alternator makes a whining sound, even with the battery fully charged. This may occur after only a short period of use. Also, it only fits specific Jeep models.
Built to meet OEM specifications
- BrandDB Electrical
- Weight11.44 pounds
Only fits specific Jeep models
May make a whining sound
Denso is a well-known name in the auto industry and offers original equipment for many makes and models. Every alternator core is subjected to a stringent quality control process before it’s remanufactured. All the hardware is 100 percent stripped and replated for quality. The part is designed to meet stringent heat and electrical requirements and is compatible with sensitive electronics systems. The alternator is also compact and relatively lightweight.
Like other alternators, this one is only designed to fit certain makes and models, so make sure you consult the manufacturer before making a purchase. Also, the product description may not match the amperage.
Six groove serpentine pulley
OE quality fit
Rotor performance and insulation tested to 600 volts
- Weight12.85 pounds
OE for many makes and models
Products undergo rigorous remanufacturing process
Compact and lightweight
Only fits certain makes and models
Product description may be inaccurate
This 12-volt, 132-amp alternator is made with 100 percent premium components to meet or surpass OEM amperage and voltage output. It’s built to be identical in fit and performance to original equipment parts. It includes major heat-related and wear items (rectifier, regulator, rotor, stator, and bearings) that can withstand excessive heat and large electrical demands. Overall, this alternator provides excellent power in high-demand conditions and is 100 percent full load tested for performance.
One of the problems with this alternator is the bushing may strip when you tighten it down. Also, there have been some complaints that it may get broken during the shipping process.
Built with 100 percent new components
Seven pulley grooves
100 percent full-load tested
- Weight5 pounds
Identical in fit to OE parts
Withstands high electrical demands
Bushings may strip too easily
May break during the shipping process
This 12-volt, 120-amp alternator is intended for the 2004-08 Chrysler 3.2-liter Crossfire and certain Mercedes Benz C Class, CLK, and Ml vehicles. It’s built to meet OEM specifications and comes with a one-year warranty. It fits perfectly and continues to produce a strong current over an extended period of time. It’s also a great value compared to what you would pay if you had it replaced at a local garage or dealership. It’s also very easy to install.
As with all alternators, the drawback with this one is that it only fits certain makes and models. So, do your research before purchasing this one from AC Delco. In some cases, you may have to use the original spool on the old alternator to get it to fit properly. It may also be very tight when installing.
Built to meet OEM specifications
Six-groove serpentine pulley
- BrandDB Electrical
- Weight14.96 pounds
Includes one-year warranty
Produces a strong current
Easy to install and a great value
Only fits certain makes and models
May be difficult to install
May require original alternator hardware during installation
This 12-volt, 105-amp remanufactured alternator is designed for 1999-2005 GM vehicles. Its components are greased for durability, so they can withstand harsh conditions. It’s built with an exact-fit design and is performance tested for sound, vibration, and exposure. The alternator meets or exceeds OE specifications and includes stators and rotors coated with extra insulation, polish slip rings, brand-new lubricated bearings and solenoids, and regulators.
The ACDelco regulator comes with a two-year, 24,000-mile warranty. However, one of the downsides is it may produce a whining sound. It may also fail and produce low output within a short period of use, and the voltage regulator may not work consistently.
100 percent new components
- Weight11.65 pounds
Meets or exceeds OE specs
Extra insulation on the stators and rotors
Only fits specific GM vehicles
May produce a whining sound
May fail over a short period of use
Best Alternator Buying Guide & FAQ
Your vehicle's electrical system requires an alternator to keep it running properly. Without one, you may experience dim headlights and brake lights, issues with the sound system, and problems with the electronic door locks. An alternator recycles electricity back to the battery so it operates efficiently.
In our buying guide below, we examine the top features to look for when shopping for an alternator as well as the different types of alternators available. We also include some advice about alternators and what you should do if you suspect yours if failing. Finally, we feature some commonly asked questions about alternators that will help you make the best purchasing decision.
Why Do You Need An Alternator?
The electrical components in your vehicle are vital to its operation. In addition to the battery, you also need a properly functioning alternator. When you drive your vehicle, the alternator restores what the battery uses to run various functions in your vehicle, including the engine and the audio system. If you want to listen to your favorite tunes, for example, you need an alternator that is up to snuff.
A lot of power is required to get your vehicle running and to keep it running. Without an alternator, the battery's power reserve will eventually dissipate. That means your vehicle will break down, which can be very inconvenient and potentially costly.
- It fixes headlights or dashboard lights that are too dim.
- It enables you to listen to music on your sound system.
- It helps you run the heating or air conditioning.
- It helps you avoid expensive repairs and breakdowns.
Types of Alternators
Not all alternators are the same. Some are designed specifically for standard automotive purposes, while others are meant to be used for marine applications or for hybrid vehicles. When it comes to automotive alternators, you have the option of using one that is new or remanufactured, and there are pros and cons to both.
- Remanufactured or Rebuilt
The biggest difference between a new and remanufactured alternator is the cost. You will save a lot of money if you decide to use a rebuilt alternator. They can be as much as 25 percent less expensive than new alternators. However, some of the best alternator brands are remanufactured with high-quality parts, while others are built with cheaper parts, which means they may not be particularly durable.
New alternators are designed to meet specific safety standards, but if you go to the shop for a rebuilt alternator, they do not have to meet the same requirements. Always consider using a well-known brand if you opt for a remanufactured alternator. These companies have a reputation to uphold and will produce high-quality remanufactured equipment for their customers.
An alternator is named after the alternating current that changes mechanical energy into electrical energy. The alternator and battery run your car's various accessories. An automotive alternator has a voltage regulator, stator, rotor, and diode. When you turn the ignition on in your car or truck, the battery power turns the starter.
The starter then turns the alternator belt by way of the accessory drive. This then spins the alternator's pulley, which causes the alternator's rotor to spin quickly. The rotor is part of a group of magnets located inside a grouping of copper wires, which is the stator.
- Marine and Train
Marine alternators are usually used in yachts and function similarly to car alternators. However, they are specifically designed to withstand a salt water environment. They are explosion-proof, so they are less likely to ignite gas mixtures in a vessel's equipment room. Larger yachts will have more than one alternator in order to tolerate larger electrical loads.
Trains also use alternators, particularly if they are electric locomotives. In this case, the diesel engine will turn an alternator, which is designed to supply electricity to the traction motors. Traction motors move hybrid and electric passenger vehicles as well as trains.
What to Look for When Buying an Alternator
There are a few things you need to consider before you purchase an alternator. First, you need to ensure that the product is compatible with your specific vehicle's make and model. Then you need to determine if the alternator's amperage matches your vehicle's requirements. Once you figure these two things out, you should be good to go.
We already noted this above, but it's worth repeating. It's crucial that you select an alternator that is specifically designed to fit your vehicle's make and model. There is no universal fit alternator that will fit every single type of car, truck, or SUV available.
If you don't purchase an alternator that matches your vehicle perfectly, it will cause a lot of issues. First, you will fail when you try to install it. Then you will have to return the component, which may cost you time and money, and you will still have to locate a replacement. Meanwhile, your vehicle may be out of commission while you’re going through the process.
The flow rate of an electrical current is known as amperage. Most stock alternators are 65 to 100 amps and are able to withstand your car or truck's basic needs, including the headlights, air conditioning, and audio system. They usually include a 10-15 percent reserve for tolerating additional accessories. If you have a high-end stereo system, use a lot of additional accessories, or have additional onboard electronics, look for the best high output alternator with higher amperage.
To check your vehicle's electrical load, you can use an ammeter. Make sure the engine is turned off; then connect it to the battery's ground terminal. Then switch each electrical component on and off to determine the amperage draws.
Tips for Buying and Using an Alternator
A clear sign that you need a new alternator is a warning light on your vehicle's dashboard. It may appear as an image of a battery. We strongly advise that you take this warning light seriously so that your vehicle doesn't unexpectedly break down. When it comes to alternators, there are several things you should be aware of to make sure they are in good operating condition.
For example, even the best aftermarket alternator will not be able to save a dead battery. The two work in conjunction with one another but can't function properly without the other. Also, take notice if you hear or smell something unusual coming from the engine compartment. This may indicate that your alternator isn't working as it should.
- One sign that your alternator is not working properly is a warning light on the dashboard. Do not ignore this light, or your vehicle may break down.
- A new alternator cannot replenish a battery that is really weak or dead because the battery won't be able to accept a charge.
- If you smell something burning, it may indicate that the belt is slipping on the alternator pulley, but this can often be fixed by tightening the belt.
- You may need to replace your alternator if you hear a grinding or whining noise, which is due to worn-out bearings or bad bushings inside the assembly.
Best Alternator FAQ:
At this point, you know the ins and outs of alternators. Still, you may have some unanswered questions about them. Whether it comes to their fit, the advantages to getting a new versus a remanufactured one, or the signs of a bad alternator, we've got you covered.
Q: How do I determine which alternator fits my vehicle?
A: As we noted previously, it’s vital that you check with the manufacturer to make sure the alternator is an exact fit for your vehicle. Be sure to match the amperage, voltage, and mounting specifications.
Q: Is a new alternator better than a remanufactured one?
A: Not necessarily. It's common in the industry to sell remanufactured alternators, and some brands use premium components that are higher quality than those used by OEM suppliers. Look for brand names and the best alternator manufacturers to ensure quality.
Q: What are the symptoms of a bad alternator?
A: You may need a new alternator if you notice your vehicle’s lights are dim or flickering, the service engine light clicks on, the engine stalls, the battery is dead, or you hear odd noises.
Our Top Pick
Our pick for the best alternator is the DB Electrical 145 Amp New Alternator for Chevrolet, GMC Trucks. The company got its start as a starter and alternator rebuild shop in Kingsport, Tenn. and has been in the business for nearly 40 years. Its products are well-known and respected in the industry. This particular alternator is easy to install and works and fits well. It's also less expensive than what you would buy in the store.