I've had the charger on for a couple of days. Went out today and hooked up the cables and started it. The battery light stayed on. I let the car run until the cooling fan came on and I shut it off. Hooked up the charger again, topped off the coolant and started it up. The light was out. I attributed that to the battery charger being connected, but when I removed it, the light stayed out. I drove it around the subdivision and it never came on. I did take the one you sent down to have it tested at O'Reilly's and it showed to be good, also. I'll return it to you.