There are described apparatus for detecting the presence of a defective cell in a lead-acid storage battery. The apparatus is included as a part of a larger apparatus for analyzing the condition of the battery and its suitability for further use in automobile lighting, starting, and ignition applications....http://www.google.co.uk/patents/US4322685?utm_source=gb-gplus-sharePatent US4322685 - Automatic battery analyzer including apparatus for determining presence of single bad cell
