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Monday, July 11, 2011

How to Tell If Your Car Alternator Is Bad - Reshared Knol

Source Knol: How to Tell If Your Car Alternator Is Bad

by eHowKnol

How a Car Alternator Works

An alternator takes advantage of the energy created by a gasoline car engine to move the vehicle. A serpentine belt is connected to the car's crankshaft. When the car engine moves, it turns the crankshaft and moves the serpentine belt. This is also connected to the alternator. As it turns it generates electricity. This electric current is used by the car while driving and is also transferred to the battery to store electricity. The power is used for things like the ignition coils, headlights, tail lights, brake lights, signal lights, interior lights, DVD player, radio, air conditioning and engine cooling fans. If the car alternator does not work properly, the car battery will eventually drain. When the battery is dead, the car wont start.

Why a Car Alternator Can Fail
There are two main reasons car alternators fail. The first is a reaction to high temperatures. Driving a car for a long time or in very hot weather can cause an alternator to stop charging. The second is a bad diode. These are vital to the charging process. As they wear out or burn out they charge the battery less and less.

Clues That Your Alternator is Bad
There are two tests you can perform at home that can give you an indication whether your alternator is working properly. Try one or both of these before spending any money on repairs:

•Try the headlight test. Turn your car headlights on while the car is running. Do this outside so carbon monoxide gas buildup doesn't become a problem. Press the accelerator while the car is in park. If the headlights dim or get brighter when you press the accelerator, your alternator could be bad. If the headlights remain the same, your alternator is probably fine.
•Try the battery test. Turn the car ignition on and open the engine hood. While the car is running, remove the negative cable on the battery. If the car suddenly stalls and dies, your alternator could be bad. This is because the alternator is not generating enough electricity to keep the car running. If the car keeps running, the battery might be the problem.

How To Confirm That You Have a Bad Alternator
The only way to confirm that you have a bad alternator is to have it tested. Any mechanic can do this but they will charge you for it. If you want your alternator tested for free, take it to an auto parts stores. Most stores will check it out for free. You will need to get your alternator to the auto service center or auto parts store to get it tested. If your car wont start, you can try to jump your battery with jumper cables and a fully charged car battery. If that does not work you will need to have your car towed. Of course, you can always push it there. The mechanic or auto parts salesperson will connect a voltmeter to the terminals of your battery. It should read between 12 and 13.5 volts. If it is less than that and falls even when the car is running, then the alternator is bad. If it reads higher than 14.5 volts, the battery is being overcharged. This could also be a problem with the alternator.

What To Do If You Have a Bad Alternator

It is very rare to have a bad alternator repaired. The work involved is not cost effective. It is less expensive to buy a new alternator than it is to replace the bad one. If you are trying to save some money, you can buy a rebuilt alternator. Just make sure that the shop that sells you the rebuilt alternator guarantees their work and its performance over a significantly long period of time. You could also buy a used alternator from a salvaged vehicle or junkyard. This can be risky since there is no guarantee how long it will work or whether it will work at all. It is also highly unlikely that a service shop mechanic will install a used alternator for you. Installing a replacement alternator yourself will save you a significant amount of money. Only attempt this if you are comfortable working on car engines and know what you are doing. An alternator is an important piece of equipment in a car engine. It must be installed properly.

What a Replacement Alternator Will Cost
Most of the cost of replacing a car alternator is labor. Most auto repair shops charge between $70 and $90 per hour for labor. Replacing a car alternator takes an average of 2 to 3 hours. This is in addition to the cost of the new alternator itself. A brand new alternator can cost between $200 and $400. A rebuilt alternator generally costs between $100 and $200. A used alternator can be acquired for as little as $50. However, you will probably have to install a used alternator yourself. For those who do not wish to do their own car repairs, an alternator replacement bill can range from $300 to $1000. The cost will vary from place to place, shop to shop and car type to car type.

What the Problem Can Be If It Is Not a Bad Alternator

It costs a lot of money to replace a car alternator. It pays to be sure that the alternator is really the problem before agreeing to the replacement. If the problem is really a bad battery, you can get a new one installed for less than $100. That's a big difference in cost. Also, check the wires connecting the alternator to the battery. If they are bad, it could impact the performance of the alternator. Check them for corrosion and make sure that they are attached securely and properly. The serpentine belt may also be loose or not properly connected to the alternator. This might prevent the charging of your battery or slow it down significantly.

By Kent Ninomiya

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