Battery Light Possessed

2000 cirrus battery light comes on after 20 minutes driving.Pull over check charging system charging 14.2 volts.Turn off start up light is out sometimes it comes back on sometimes it doesn't. Already paid $420.00 on diagnostics to no solution help please.

I've been having the same problem for years now. I can usually tell the Battery light is going to turn on because the odometer gets this flicker and dims ever so slightly. It's so frustrating, but as you indicated the charging system is working just fine. I keep one of those $4 harborfreight meters in the car in case I'm at a convenient place to check the voltage.