How do you know when to replace the alternator?

Answer 1

You need to get it tested. Auto Zone, Checker Auto, Kragen Auto or any of the local consumer auto parts distributors will check it for free. Call around if you have any questions. In general, if you want to run a primitive test yourself you can use a volt meter. Test the voltage before starting the engine, it should be around 12 volts, maybe a little lower if the battery isn't fully charged. Then start the engine. With the engine running and about 1000 RPM you should have 13.5 Volts at the battery. the easiest is to go to the local parts store most can check them right on the car. compare engine off voltage to engine running voltage. If it does not go up during engine running it is probably bad. Hey Lakisha==Take it to Auto Zone and they can check it out for free. Goodluck Joe If it is makeing a noise or is not putting out at least 13.5 volts it is bad. Take the car or the alternator to an Auto Parts store and have them load test the alternator to be sure. Just disconnect one of the battery post.If engine dies your running on battery.Are have an auto store check it for free they test load it. E.C.H Depending on the vehicle< it could range from the alternator gauge not registering a charge to an alternator light on the instrument cluster staying on. The easiest way to check this is to get a voltage meter and run it across the two terminals on the battery with the engine running. If you get a charge of 13.8 +/- 1 volt then it is charging if below with the engine running then the alternator is done. when the car is started disconect your battery and turn on your lights. if they are dim or dont come on your altinator is bad. Use a volt meter and measure the voltage on the battery with car NOT running. It should read 12 volt. Turn on the engine and measure the voltage on the battery again. If the alternator is good, the voltage should be 13+ or 14+ volts. If the alternator is bad, the voltage would be the same or less than 12 volt. If your battery is bad, the voltage would be less than 12 volt. You can also bring your car to an auto parts store and they will check it for you for free. have it tested,loss of electrical power is usually battery or alternator if happens slowly Disconnect the battery cable and see if your engine keeps runing. If the engine stops running your alternator isn't putting out any electrical power to your engine. Replace your battery cable and go have your alternator tested. If your alternator is good then start looking for a short somewhere. Sometimes the bearing inside the alternator will begin to make noise, not always. You can started the car, turn on the headlights, and then other accessories to see if the headlights dim when they are turned on. Alost of places like Autozone, Checker, and NAPA can bench test the alternator for you. Does your battery go dead when you drive for any length of time with the headlights on. If so there is a pretty good chance that your alternator is bad especially if the voltage regulator in internal (inside the alternator)