Test encased storage batteries for air-tightness.
What does a Spark Tester do?
Tests encased storage batteries for air-tightness, using electric spark tester: Places frame of tester over battery container and presses plug terminal of testing apparatus to posts of battery. Moves frame of tester over surface of container to detect leaks indicated by bright sparks emitted at contact points. Examines assemblies for defects, such as uneven sealing, misplaced intercell connectors, and covers. Attaches slip to rejected batteries indicating type of defect. May stamp polarity symbols on posts, using hammer and dies.