Abstract: An electrical storage cell includes a charge producing compound in the interior of the cell which inherently and without the addition of additives or structure changes color as the charge of the battery is dissipated. The battery includes a window in either the top or the side of the battery to provide visual access to the charge producing compound. A suitable color chart is positioned around the window through the battery housing to enable an observer to see the charge producing compound in the interior of the battery and to compare the color of that charge producing compound against a color on the comparison chart to determine the battery charge remaining in the battery.