Ok my alternator is a one wire from summit racing. It is a 100 amp and im running two electric fans and an msd ignition. Now when I fire it up after sitting over night I can check the voltage and it reads 13.75 volts while idling. If I drive 15-20 miles down the road the voltage on my meter starts going down very slowly. Once I get back home, driving a total of 30-40 miles its almost at 11 volts on my meter. Its worse if I drive at night with the lights. It drops the meter almost two volts when I turn my headlights on. Is my charging wire too small?? I think its a 10 or 12 gauge and it goes back to the battery(in the trunk). The belt is tight enough and doesn't seem to slip...isnt the alternator supposed to put out like 14.5-14.75? I bought it new through summit and its been this way ever since I got it.