First of all, is the alternater charging 14 volts? Also you might have something draining the battery. If you have a volt meter, take the ground wire off the battery, take one lead from the meter and hook it to the battery and the other to the cable. ( you might have to switch wires on the meter) If it reads 12 volt, there is somthing draining the battery. With the meter hooked up, take the power wire off the alternater, if it goes to zero, you have a bad alternater. If you take the wire off the alternater and it is still 12 volts, start taking fuses out one at a time to find what is drawing power.normally the alternater will draw around five vols, thats fine
