Disclosed is a portable charger device that includes a chamber to hold at least one rechargeable charging battery, and at least one controller. The controller is configured to determine a first charging current level to apply to the at least one rechargeable charging battery such that the at least one rechargeable charging battery achieves a first predetermined charge that is reached within a first period of time of 15 minutes or less, apply to the at least one rechargeable charging battery a first charging current substantially equal to the determined first charging current level, determine a second charging current to apply to the one or more external rechargeable batteries, and apply to the one or more external rechargeable batteries a second charging current substantially equal to the determined second charging current level, the second charging current being drawn from the at least one rechargeable charging battery.