Lexus Repair: charging problem with a 1993 Lexus LS400, lexus ls400, alternator problem

Question
My daughter is a single mom and owns a 1993 Lexus LS400 with approx 170k miles on it. This weekend she was coming home and stopped at a traffic light.  The engine just died and nothing would work, a mechanic happened by and showed her how to get the vehicle out of park and off the road. I just put a new 75 month battery in the vehicle last month but it was completely dead.  I tried to jump start the vehicle and it started until I took the cables off then it died.  I took it to an auto electrical specialist today (we have no Lexus dealers in the area) He checked the alternator and it checked just fine, the battery was charged and he cleaned all the connectors and the car started fine. I went to pick it up and enroute home the battery indicator on the dash came on. When I got home I shut it off and restarted it several times and it seems to be fine but this is a complete mystery to me.  Thanks for your help

Answer
Hello Joe,
  It look like a alternator problem to me.  What kind testing did they perform? Do you have the testing information off your hand? How many volt does the alternator putting out? Please take a close look at your power steering pump.  The power steering located directly above the alternator.  If the pump leaks, which is most of the time. It the fluid will find it out to the alternator. Please provide us the alternator output. Thank you.
JP Importz
Dallas/Plano Independent Lexus and Toyota
Repair, Lexus and Performance
www.jpimportz.org
214-221-3135