92 Mazda mx3 alt problems

Hi this is my problem, I bought this car drove it home on the whey the alt. light came on and so I had it tested failed, put a new one in, check if it was charging for about 5 min and quit charging. Put another new alt. in this time it lasted 2 days but the alt. light never came on for both new alt. could it be 2 new alt. being bad, I checked charge light and it works, I have no burnt fuses. Any one have a clue of what is wrong. Or is there a test a person can do to see if something is shorting out the alt.

Thanks Meck46

snapon makes an agr that can test ur battery starter and altenator. all u do is hook it up to the car battery and it will give u all u need. remember u get what u pay for.