Abstract: Apparatus and methods are provided for providing flexible and repairable testing capabilities, including destructive testing, for systems that generate or absorb heat such as energy storage systems. One embodiment can include a heat exchange system adapted to contain and maintain a fluid at a predetermined temperature, thermally conductive tubing in direct intimate contact with a plurality of heat sinks, thermal sensor assemblies, and an sample vessel receiver structure where the thermal sensor assemblies, heat sinks removeably attach to different sections of the inner containment structure so as to measure heat flow into or out of the inner containment structure's different sections, and a test cell enclosure which is adapted to contain forces and output from destructive testing of samples.