I think the OP meant 0.54 Amps.
It's interesting the previous owner replaced the alternator, so this might have been going on a while, OR they put in a bad alternator.
I saw a place where they rebuild these, and it's amazing they can do anything right. (an auction at a bankrupt company with an hiding place for undocumented workers)
Disconnect the alternator output and if that doesn't drop the current, look at the voltage regulator.