An alternator tester having improved heat dissipation. The alternator tester has a housing and a circuit board including tester circuits. The housing has a size suitable to be held in one's hand. The housing includes a first compartment for receiving the circuit board and a second compartment for housing a load. The load is coupled to an alternator when the alternator tester conducts a test on the alternator. The second compartment has an opening disposed on one side and a fan disposed on the other side. The load, the opening and the fan are substantially in line. The opening and the fan form an air flow path, when the fan is in operation, the heat generated by the load is dissipated to the surrounding air and drawn out through the air path.