If you don't have access to a battery charger, take it to Autozone or someplace that can do a battery load test off the vehicle. Usually this test requires a fully charged battery, but if its not fully charged, the tester will charge the battery, usually an hour or so, then do a load test on it. THis will serve 2 purposes for you, test your battery, and charge it. This is almost always a free service at those types of stores. Good luck...
Dan