A battery-based portable power supply includes a battery pack that is configured to protect the batteries and components therewithin. An outer tube protects inner components from impacts that can be expected in transport and usage. A suspension system within a battery pack of the power supply protects the batteries from jolts and bumps. The batteries can be removed and replaced. A switch structure for actuating the electrical outlet is disposed within the battery pack. The switch structure is actuated by compressing the battery pack from outside.