It's likely your battery died because your alternator isn't putting out the juice to keep everything running. If all the connections to the alternator are clean and tight and the belt is in good condition and not loose your alternator has likely bit the dust. You can pull the alternator and get it tested in most shops, but if it has some years on it I'd just go ahead and replace it.

I had an odd-ball occurance of the slotted bar that holds the tensioning bolt for the alternator, breaking off the bolt that attached it to the engine mounted bracket. The alternator was just sort of bouncing on the belt.
At high revs it would generate, at low just enough to keep the engine running. I wouldn't wish that on anyone. It was a PITA to get that bracket off to drill out and retap the busted bolt. I only mention it as it's
something to look at if nothing else presents itself. It will be real obvious when you check the belt tension.