The charger has detected a battery and is currently pumping in that 1.5-amp current. It’s the "working" phase. Green Light (Charged/Maintaining):
A: Many Autocraft 1.5A models have a “wake-up” feature. If voltage is below 3V, charger may not detect battery. Use a manual charger briefly to raise voltage, or replace battery. autocraft 1.5 amp battery charger manual