Put a multimeter on it while it's running you should get a bit over 14vdc if the alternator is running. If not it's a good chance your alternator is not working.
If you have no meter and can get it to a parts store in the morning they should be as to hook you up and test it and the battery.
95' YJ 4" lift 33"x12.5r15's D30/8.8 locked with 4:88's
USMC Jeep Club #6
"Why in hell can't the Army do it if the Marines can. They are the same kind of men; why can't they be like Marines."
Gen. John J. "Black Jack" Pershing, USA; 12 February 1918