An asymmetric battery testing apparatus tests a battery unit. The battery testing apparatus includes a first wire, a second wire, a third wire, and a testing circuit. The testing circuit includes a test-enabling unit and a control unit. Each wire has a resistance. The test-enabling unit includes a resistor to obtain a first resistor voltage value and a second resistor voltage value. The control unit obtains a battery internal resistance or a battery internal conductance which is a reciprocal of the battery internal resistance of the battery unit according to a battery internal voltage value, a wire voltage value, a first testing voltage value, a second testing voltage value, a testing resistance, the first resistor voltage value, the second resistor voltage value, and the resistances. Accordingly, shorter test time, lower contact failure, higher accuracy, lower power consumption, lower costs, and smaller size are implemented.