If you notice the battery light illuminated on your gauge cluster in your 1st generation (2001, 2002, 2003, 2004, 2005 & 2006) Acura MDX you probably either need to replace the 12V battery or change the alternator. Check out my DIY guide for changing the alternator by clicking on the text link or thumbnail image below. (The procedure is the same for any Honda or Acura vehicles with the VTEC 3.5L V6 engine such as the Odyssey, Ridgeline, Pilot, RL, TL, Inspire, Accord, TSX, RLX and Legend.)
2001-2006 Acura MDX Alternator Replacement Guide
If you test your alternator and it is working properly, check out my 12 volt battery replacement guide at the link below.