Ask your local auto parts store to do it.
Charge it, replace it,test the alternator,Charge it, replace it,test the alternator,
Car would either have to be running or alternator removed for bench test
run it and then disconnect the negative wire from the battery if alternator dies its bad.
with a voltmeter
Either drive to your local auto parts store and have them test it in the vehicle or you can remove the alternator and take it to your local auto parts store and they can bench test it for you.
Full fielding is a diagnostic test of the alternator You make the alternator work full out and measure the voltage and amperage output to test it against a published specification.
Battery light usually means alternator not charging. Most common solutions would be be a bad alternator, bad connection, or loose alternator belt. If the battery and alt test ok than check the connections to the alternator and battery.
The alternator must be running to test without disassembly. If you remove it, many auto part stores will test at no charge. One test is a voltage test. Start the engine and use a multimeter to check the voltage at the battery. It should read between 13.5 and 16 volts. Any less or more and the alternator is bad.
it could be your crank posistion senson or alternator failing get a dia and a load test on alternator
TAkeit to the Auto Zone store and they will check it free.
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.
Auto parts shops like AutoZone will test the alternator for free.