Abstract: A battery tester adaptable for testing both 1.5 and 9 volt batteries is disclosed. The tester includes an indicator lamp carried by an arm extending over a base which receives the battery to be tested. The arm is attached to a plunger, vertically slidable within a stem connected to the base. A bias spring urges the arm to an uppermost position on the stem. Conductive means on the base, stem, plunger, and arm provides a partial circuit between the lamp and a first pole of a cylindrical 1.5 volt battery in contact with the base. A resistive terminal is attached to the arm near the indicator lamp. Depression of the arm from its uppermost positions places a protruding terminal on the lamp in contact with a second pole of either a cylindrical or rectangular battery. Such depression of the arm also places the terminal secured on the arm in contact with a first pole of a rectangular battery. Thus, a circuit is completed between either type of battery and the lamp.