Thank you Pelicaners,
The problem was indeed the indicator light. I did not know that if the light did not work, the alternator would not properly charge the battery while driving.
It turns out the paddle ends of the light housing were badly corroded. I cleaned the wire ends and the paddle/connectors. Now the light is brighter than ever.
Checked and the battery had 13.01 volts when cold and 14.7 when the engine was running. I think the problem is fixed.
Thank you again
