battery?

What about your alternator. Is it good. If you have a bad alternator nothing will come on in the the car.

My very well be your alternator. If it is running and your lights, power windows and your radio is or are running weak, then the car is being drained. I would guess that it is the alternator. 2nd answer may be the battery. If you try to start it and you get no more then a click, then it may be the starter. Hint : Get the vehicle started and while it is running, take the negative terminal off of the battery post. If it shuts or stalls quickly, then it is most likely the Alternator.

Removing the battery post while the vehicle is running can ruin your alternator, that's an old diagnostic trick from the days of 6 volt systems with generators, these days all you need is a basic multimeter set at DC and read the voltage while the vehicle is running. If you're between 14.1 and 14.7 volts you're in the clear. Your problem to me sounds like a parasitic draw draining your battery and is fairly easy to test yourself with a basic multimeter... with the vehicle off and a fully charged battery (over 12 volts) your set the multimeter to read amperage, hook it up to the battery, take your baseline reading them remove (and replace) one fuse at a time until the amperage reading drops significantly. Youve now found the circut in which the draw is happening, from there you need to trace what is causing it, believe it or not I've seen a blown interior bulb cause a drain on a battery. The reason its costly for the mechanic to find it is because it's very time consuming in most cases. I hope this helps you some