The present invention is an electrochemical double layer capacitor (EDLC) series stack formed into a single electrolyte cell structure. The concatenated multiple electrode assembly stack has electrode assemblies electrically connected in series. The electrode assemblies have a double-sided activated carbon electrode formed on a current collector. Power tabs are connected to the end electrode assemblies. An electrolyte is also provided. A poly bag contains the electrolyte and the electrode assemblies. The electrode assemblies form a double-sided activated-carbon electrode on a current collector. The EDLC stack has a number of segments and mass free zones separating them. The segments are folded so that mass free zones are disposed at the apex of each fold.