Now you've injected a whole new dimension to this problem. If your battery is bad it won't crank the engine over "just fine." A battery either has juice or it doesn't.
I think what is happening is that you took your battery back and some unknowledgeable clerk THINKS the battery was bad. How did they determine that? Did they load test it?
There is something totally different going on here than you originally explained. We thought you were saying the batteries wouldn't hold a charge after a month.
You have got to be more specific when asking these questions if you want to get a reasonably accurate answer. It is hard enough coming up with solutions via a computer anyway, because we are trying to diagnose it without the benefit of seeing the vehicle.
Don
