The Nissan Path

2003 LE. battery/alternator light on at idle, but goes off at over 2400rpm.
Is it a weak alternator, or a bad battery?
Over the last year (before this happened) , the car would not crank few times and I had to jump it. I Thought it was a bad battery (Interstate batt. only 1 year old) but now the alternator light problem started. I installed a disconnect thinking there is a drain somewhere, but did not help the situation.
Could it be the bad battery overloaded the alternator to a point of failure?
Or a weak alternator did not charge at low rpm (but light did not come on until now)
Please help

You won't know until you have them tested. Most major auto parts stores will do this for free. You also want to make sure the battery cable connections are clean and tight. A properly operating charging system will charge from 13.2v to 15.5v, with and without loads (headlights, heater fan, etc.) "on," at idle and at 3000RPM.