A reserve battery that is activated via a low energy mechanical force. The reserve battery generally includes a battery case having an electrolyte compartment at a first end and an electrode compartment at a second end, a first terminal having an external button connected to the case at the first end, and a second terminal connected to the case at the second end. A movable ampoule is movably positioned within the electrolyte compartment. A bias member is located within the case between the external button and the ampoule and a porous cutter is positioned within the case between the electrodes and the ampoule and supported by an inverted U-shaped support structure. When an external force is applied to the external button, the bias member transfers an internal force to the ampoule to cause the ampoule to engage the cutter and allow the electrolyte to release thus activating the battery.