Ignition Light on '80 B

[glemon]

I have an 80 B, the ignition light has started to come on when idling even if the idle is over 1000 rpm, doesn't cut out until 0ver 1500 rpm or so, it comes on intermittently, but more lately, I know on the cars with generators this indicatss bad charging (generator/voltage regulator) I feel like a newby with this "new" car with the alternator and other modern features.

Do I have a charging problem? What should I check?

 

[DrEntropy]

First, check belt tension.

After that it's on to the alternator. A check with a meter at the battery terminals for a 13.5~14V output, and a check of the specific gravity in the battery cells.