My battery light started to come on after around 30 seconds of idle. They have a smart charge system on, if you listen you can hear the relay clicking when the light goes on and off, this will also drop the current on your reading. Mine was the plug on the loom that connects to the alternator as mentioned above.

This was after I fit a new alternator (which I was doing anyway with power steering pump, water pump, all pulleys, new belt etc.)

I simply unplugged it, cleaned the 3 pins and contacts, then put a little vaseline on, its been perfect since.