I am having trouble with car draining car battery

What is your question?

Just bought a battery from Walmart for this car woke up the next morning the car won't start had the alternator tested oreilys I said it come back good had the battery tested and they said it was drained dry overnight what could be the problem with this Taurus

What makes this problem better or worse?

When battery is new car work great

How long has your 2000 Ford Taurus had this problem?

5 days