a continuously monitored battery operated power supply for maritime applications includes four batteries which form a parallel connected pair of banks in which the cells in each bank are series connected to each other . a wheatstone bridge circuit connects a midpoint between the plurality of cells in the first bank of battery cells and a midpoint between the plurality of cells in the second bank of batteries . the circuit also includes a volt meter for indicating a voltage change due to the degeneration of a cell when the voltage change exceeds a predetermined value .