Hi, First time posting, so be gentle

Can anyone tell me what output should be coming from a TDCI "smart" alternator when disconnected ie - out of the car, mine is showing only .8 volts, but am not sure if this is happening because its not plugged in, I tested it by connecting a drill and spinning it to 3500rpm so speed should be fast enough. Any help would be greatly appreciated before I buy a new one if not needed. Thanks, Jamie.