A promising approach for storing heat in a compact, light and cost-efficient way is the usage of metallic latent heat thermal energy storage systems. Metallic phase change materials are energy dense and highly thermally conductive, which makes them interesting candidates for mobile applications. However, extensive experimental data for a prototype configuration are missing, and the heat extraction characteristics are yet to be elucidated. Therefore, this article focuses on the experimental investigation of the heat extraction characteristics of a novel storage concept realized as a small-scale functional demonstrator. The storage is based on an aluminum silicon alloy and a box-shaped graphite container design. Heat extraction is achieved by forced convection of ambient air utilizing a controllable fan, while charging is realized by electrical heaters. Experiments were carried out successfully for various constant fan power rates, constant mass flow rates as well as for a controlled heat output in an operating temperature range between 650 °C and 100 °C. Around the phase change temperature of 577 °C, a significant drop in performance is observed when the storage material changes its state from liquid to solid, indicating a strong change in thermal contact resistance. In the liquid state, the heat extraction is highly efficient, with a ratio of electric power consumption of the fan to thermal heat output of smaller than 0.7%. In the solid state, a thermal discharge of 1 kW is achieved down to a storage material temperature of about 240 °C. Based on the experimental results, the functionality of the novel storage concept could be proved. The current work contributes beneficial data and physical insights for prospective simulations and prototype design studies on metallic latent heat thermal energy storage systems.