Ignition charging at idle speed

[BDurgin1@aol.com]

My car idles between 500-750 RPM. The ignition light glows quite red at this
idle speed. The fan belt feels pretty tight and the generator is good. This
is a '64B , positive ground.
At about 1000 RPM's the light goes out. Should I be concerned about this?
Should I "up" the idle or not worry.I like  a low idle sound and according to
the bookk, I'm OK for an 18G Engine.

Some collective "net" wisdom,please.

Bruce Durgin