Patent ID: 8957640
Filing Date: 2015-02-17
Classification: G01R,H01M,Y02E

Abstract:
1. A method for calculating the state of charge of a sodium-sulfur battery constituted by connecting an s number of plural electric cells in series to form a string, connecting a b number of plural strings in parallel to form a block, connecting an n number of plural blocks in series to form a module, and then connecting an m number of plural modules in series, the method comprising steps of: measuring, by a voltage measuring apparatus, an open-circuit voltage of each of the n blocks in each of them modules at a time t following completion of discharge of the sodium-sulfur battery; determining used capacity Qu [Ah] by using open-circuit voltage; determining residual capacity in final year Qsf [Ah] according to expression (1) by using a conversion function f1 on the basis of an equivalent cycle Cef in the final year calculating the state of charge Qr according to expression (2) by using a product capacity Qa [Ah], the determined Qu and Qsf