2007-05-22 11:02:17 · 7 answers · asked by Anonymous in Cars & Transportation ➔ Maintenance & Repairs
Easiest way...take it to Auto Zone or similar who can test both while the parts are still in the car.
Most of the answers below are valid...BUT DO NOT remove the battery cable with the engine running!! Modern electronics are very sensitive to voltage spikes. Beyond that you are creating a spark in the presence of HYDROGEN. A battery could explode in your face removing that cable and causing a spark.
2007-05-22 11:06:41 · answer #1 · answered by Anonymous · 0⤊ 0⤋
You can take it to autozone and they will do a test of your charging system for free, they can do a alternator test and load test of the battery at the same time. If you are a do-it-yourself type of person, the best tool you can have for this test is a multirange test meter. Just start the engine and let it run a few minutes, take the leads, to a test on the alternator by placing the red lead on the terminal on the back of the alternator and put the black lead on a good grounding point. (not the battery ground) note your reading. Now, turn on some of the electrical accessories to put a load on the system, such as the headlights, take another test on the alternator, your reading on each of the test should not be less than 12.5 volts and absoutely no more than 13.5 volts on a 12 volt system.. If your test reads less or more than the range I just gave, you have a bad alternator. The alternater charging too much is just as bad as not charging enough. Now as far as your battery, it should be load tested with the engine off and should be done by someone that has experience in doing this or if you have a friend that can do this for you. The average homeowner does not have the tool needed to do a proper battery load test. Please do not remove the battery cables for any reason while the engine is running, because all of the electronic components and sensors that are on a vehicle these days can be damaged if there is a interrupt or surge of voltage.
2007-05-22 18:23:46 · answer #2 · answered by bobby 6 · 2⤊ 0⤋
the old method of removeing the positive battery cable, doesnt work on many new cars. if you have a multy meter its easy. test the battery to see if it has 12.5 volts. or take it to auto zone or a murrays. both methods will prove out the battery then start your car and test voltage at the battery cables it should be between 13.5 and 14.5.turn off car and test again, reading should be atlease 12 volts this tell if the altenator is working.
2007-05-22 18:15:27 · answer #3 · answered by rock 2 · 0⤊ 0⤋
Start the car, then disconnect the battery. If the alternator is stuffed, the car will die as no electrcity will be fed to the spark plugs. If the car keeps running, it's your battery.
Do you have a maintanence free battery? If not, when was the last time you checked the fluid level?
2007-05-22 18:11:04 · answer #4 · answered by Jason C 2 · 0⤊ 1⤋
I would check to see if the interior light is dimming while the car is running. The best way is to go to an Autozone or Advanced Auto and ask them to hook up the ARBST machine, which is free and that will tell you if the battery is bad and or if it is the Alternator.
2007-05-22 18:07:31 · answer #5 · answered by Anonymous · 0⤊ 0⤋
hi,,, load the battery, by turning on the lights , fan to high, and then start the engine. if it fails to start, battery is weak/bad.,,, by running the engine(to recharge the battery) and with a dc volt meter, nonfluctuating voltage at the battery should read 14.5volts max, indicating a good alternator. :)
2007-05-22 21:40:04 · answer #6 · answered by charlie 5 · 0⤊ 0⤋
The headlights will not be as bright as they should be when the alternator is going bad.
2007-05-22 18:13:31 · answer #7 · answered by deadbydawn425 1 · 0⤊ 0⤋