Some embodiments are directed to a dual activation mode thermal battery for powering a load. The thermal battery can include a first power source activable upon receiving mechanical energy. The thermal battery can also include a second power source activable through one of the electrical power produced by the first power source and external electrical stimuli, the second power source is configured to, upon activation provide a voltage for powering the load, wherein the first power source and the second power source are thermally and electrically isolated and the initiator thermal energy output from one initiator is prevented from initiating the other power source directly.