Parts of An Alternator and How They Work

It's good to know what makes up an alternator, that way you can be prepared for the automotive language used by your parts professional.

The housing of the alternator is usually made of aluminum. The housing is made with bolt holes, so the alternator can be attached to the vehicle. The internal parts are made up of a iron core called the strator. This core is surrounded by thousands of copper wires that are electrified by a rotor spinning inside these copper wires. This creates a magnetic field and AC current. Since vehicles need a DC current, there needs to be a part that converts AC to DC. That part is called a diode pack and it allows the current to flow in one direction. From there, the current is sent to a voltage regulator, which regulates how much voltage is sent to the battery. This is where the power comes from to keep our battery charged.

Remember, the voltage regulator can fail and getting too much voltage to your battery will cause the battery to fail, too. The proper amount of voltage for a battery is about 13.5 volts to 14.5 volts, exceeding this voltage or decreasing this amount of voltage will cause alternator failure and the battery will fail.

Replacing an Alternator

The alternator is the charging system on a vehicle. Some alternators have more amps than others and some are more expensive than others, but all serve the same purpose. When replacing an alternator on any vehicle -- no matter if its a truck, car, SUV or van -- make sure you can access the bolts. Sometimes this is not as easy as it sounds, especially on front-wheel drive vehicles. It's not uncommon to find yourself removing other parts to be able to reach the bolts to remove the alternator. Another good idea is to make sure you find the belt configuration diagram, this is typically found under the hood of the vehicle or in your owner's manual. You will need this information when reinstalling the belt, whether it be a serpentine belt or just a single alternator belt. The next step is to have tools and a new alternator readily available. Pay close attention to how the alternator is connected to the engine and with a crayon or marker, mark the location of the alternator prior to removal, this will give you an idea of where to put the new alternator so the adjustments won't be a guess. There are usually two areas of concern: the adjustment area, which allows you to move or swivel the alternator into position when loosening and tightening. It also allows for the tension of the belt.

Most vehicles have tensioner pulleys and like any other alternator set, requires you make proper adjustments prior to tightening the alternator completely. The belt can be a bit difficult to remove on front-wheel drive vehicles because of the location of the belt or belts. Take your time and be patient. Look for the wires connected to the alternator, unplug them and proceed to remove the bolts holding the alternator in place. Start with the bolt that allows for adjustment, this should keep you from getting your hands smashed by a moving alternator. Move to the second bolt and remove it. If there is a third bolt, proceed with it, even though its uncommon to find a third bolt holding an alternator in place.

Once all bolts and wires are removed, the alternator is free from the engine. Start the installation of the new alternator. Remember to start with the bolt that does not allow for adjustments. Do not tighten completely, hand tighten or tighten only so that the alternator can be moved for adjustments. Replace the belt, making sure it is going around the pulleys correctly. Once the belt is on, make the proper adjustments and tighten the alternator. Plug the wiring back into the alternator. Now you have replaced your alternator.

Do I Need an Electrical System Upgrade?

Like all aspects of your car, your electrical system can be exponentially upgraded. Perhaps you have a work truck for on site welding, generators, etc. or you have a crazy sound system that requires extra amps - you will need to upgrade your alternator.

So, a regular car alternator provides between 60-90 amps while a high powered alternator will support over 200 amps for after market accessories. Choose wisely - assess what you really need (in terms of power) and then shop around. An alternator upgrade tip: although you may think the alternator is the only thing you need to worry about when you upgrade your system, you also have to upgrade your wiring so it can hold the juice.

The Case for a Rebuilt Alternator

So you need an alternator, and you need to save money? You can get a rebuilt alternator and save some money without losing reliability. A bosch alternator, for instance, has an exellent warantee and is rebuilt with all of the most important components.

This way, you get a great car part without shelling out a ton of dough. If you go with a rebuilt alternator, make sure you go with a good brand name. Super cheap car parts are not the answer - the key is to get a good buy. Additionally, you can get these rebuilt alternators from reputable car parts providers so you have a way out if it does fail (which it won't!).

What To Do If Your Alternator is Failing

Is your car having the following symptoms?
• Dim lights
• Hard starting
• Dead batteries

This may mean your alternator is on its way out! Here is how to troubleshoot:
1. Grab a simple multimeter, digital or otherwise
2. Check for loose connections to and from the battery, to an from the alternator etc.
3. Once you have established that the connections are secure, measure the battery voltage with your multimeter when the car is on and off (maintain all safety precautions).
4. Measure the voltage from the output of the alternator.

Chances are you are going to see a problem with the battery or with the alternator because issues with your electrical systems usually come from one of four things:
• Battery
• Alternator
• Short Circuit
• Bad Voltage Regulator (in the classics)

What is an Alternator?

An alternator is the base of the charging system of your car. Not only is it integral to all of the electric systems of your car - the radio, the lights, the fan etc. - it also keeps your battery charged. When cars were first built, car manufacturers actually used small generators for their electical systems. Alternators offer more efficient power and they are also safer. When your car alternator fails, so does your car as your battery is completely depleted.

When your battery light goes on, it may be the battery, but 9 times out of 10 it has something to do with a failing alternator. For newer cars, a mechanic is almost always necessary for a swap, but that shouldn't stop you from buying your car parts yourself. By shopping around on car parts websites, you may be able to get the part for less money and just provide it for your mechanic.

Old School Electrics

In older cars, like your stock mopar for instance, your alternator was paired with a voltage regulator which prevented your alternator from over charging your system. Nowadays the voltage regulator is built into your car alternator, so you don't have to worry about wiring to and from the voltage regulator and alternator (as you will soon learn, fewer connections makes for easier troubleshooting!). If you have an older car, it is advisable to replace both of these parts with a newer version. Old voltage regulators can be tweaky, and it is really best to take them out of the loop if you can.

Alternator Repair and Upgrades

Not many people will tackle a job like repairing an alternator, but some find it very cost effective to do so.

For those who would rather replace an alternator, here are a few tips that may change your mind. Consider the cost of a replacement or an upgraded alternator.

For a 2000 Chevy Silverado, a replacement can be up to $250. For an upgrade, double that. For repairing the same alternator, depending on the kit you want to purchase, the cost is between $30 and $70. For an upgrade, add anywhere from $5 to $70, depending on the upgrade, vehicle and its use.

Be aware of your vehicle's capabilities before attempting an alternator rebuild. Know your vehicle's intended use and do not go overboard with a rebuild. Don't exceed or decrease the amount of voltage or amps that is described by the alternator manufacturer.

Alternator Testing Myths

There have been many, many suggestions when it comes to testing an alternator for the appropriate voltage or amperage.

Magnet Tests: Supposedly, if the back of the alternator housing is magnetized or if the alternator is going backwards, then the alternator is going bad.

The Alternator Can Fix Itself: If an auto part could fix itself, there would never be any reason for a mechanic.

A lot of myths are floating around about auto parts and how they can be fixed or tested, but in reality auto parts go bad, malfunction or fail. Just about any auto parts store and most dealerships test alternators, starters or other auto parts and will usually test them for free. These tests are done by computerized machines that are more effective than any other method. These are very accurate tests, and should be used whenever possible.