Hi,

I have been dealing this problem over a year. Every time I start the car, I have to let rpm go over 2000 rpm to get charging working. When battery indicator goes out in dashboard, I can heard a relay click under dash.
Diagnostics show no errors and I have replaced alternator and electrician replaced some relays under the dash, but problem remains

Sorry for my bad english

my understanding is that the light will only go out once the voltage generated is greater than the battery voltage (whatever that may be when the starter is switched off) as it's a new alternator I would be checking the alternator to earth system      but you will get an expert thro' here soon   (I'll get me coat)

ps check for a full 12+volt feed to the alternator

Also check the fuse box on top of the battery for signs of corrosion/melting