Device for diagnosing of the state of corrosion of a battery, in particular one of a vehicle

An indicating unit (9) is fixed above the battery electrodes and has a cylinder (11) which is immersed in the electrolyte. The cylinder contains a piston (13) which is held in position by an indicating element (23) against pressure from a spring (22). When the indicating element breaks due to corrosion the piston moves upward and a coloured piston cap (17) becomes visible through a transparent material (25) with bevelled tip (27) An Independent claim is also included for : A battery which uses an indicating element to restrain a spring loaded piston with coloured cap