BMW Repair: 1987 325e Alternator, field mode, maximum voltage

Question
Hey Don,
I just replaced the alternator on my 325e. The Battery is fully charged. I did something which i know is not good to do, but while the car was running I pulled the pos cable off and the car went dead. So back to the alternator. Is there a possibiltiy that my belt is not tight enough? It is turning the alternator. I also left it sitting over the weekend and put a voltmeter on the battery and it is still charged so I dont think I have anything draining it. Thanks for your help.
Lee

Answer
Why would you pull the battery positive wire off?The car needs a battery to charge,by pulling the wire off you put the alternator into a full field mode(15volts or more) as it thinks the battery (which isn't there) NEEDS MAXIMUM VOLTAGE.This idea you have is something that went out in the 50's the 1950's.The battery needs to be there.If you are in question about it charging.....use a voltmeter.It should be 13.7-14.2 volts.Also if it isn't charging,check to see if when you first turn the key on the battery light illuminates.If the bulb is burnt out it will not charge!