There is a certain "low" threshold before the alt light comes on. It can also be burned out.

Check your voltage regulator and make sure all connections are clean.

A coolant leak can cause problems for the alternator, if it gets totally soaked and saturated with water and coolant.

How old is the battery? Also, was the battery electrolyte level properly maintained? Low levels will kill a battery.

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

99 W210 E300 Turbo Diesel, chipped, DPF/Converter Delete. Still needs EGR Delete, 232K

90 Dodge D250 5.9 Cummins/5 speed. 400K

Gone and still missed...1982 w123 300D, 1991 w124 300D