Accu'mula'tor, a name applied to a kind of electric battery by means of which electric energy can be stored and rendered portable. The cells of such batteries contain grooved lead plates and lead electrodes. The grooves in the plates are filled with different substances, a paste of red lead for the positive plate and litharge for the negative plate. The plates are moistened with water containing sulphuric acid. The batteries are charged by connecting them with a dynamo, and will retain the electricity until it is required for use. Accumulators are frequently called storage batteries.