A method for producing electrical energy in a munition includes; initiating a thermal battery contained within the munition to generate electrical energy; dumping the electrical energy generated by the thermal battery into an electrical energy storage device before the thermal battery becomes inactive; and using the stored electrical energy in the electrical energy storage device over a period of time. The initiation device can be an inertial igniter, the electrical energy storage device can be a capacitor and the thermal battery, initiation device and electrical energy storage device can be configured such that the initiation device and electrical energy storage device sandwich the thermal battery.