Abstract: Charging devices, modular adapters, and circuits are provided. One charging device including a body including a rechargeable energy storage device and a housing. The housing includes at least one first coupling portion. The charging device further includes a modular adapter including a second coupling portion configured to be mated to the first coupling portion of the housing. When mated to the housing, the modular adapter is configured to be electrically connected to the rechargeable energy storage device. When the modular adapter is mated to the housing, the body and the modular adapter form a single integrated and substantially rigid structure.

Abstract: A reconfigurable battery pack power system with interchangeable accessories has at least one modular, portable, rechargeable battery module having a first side, the first side having a first contour and a mounting port and a power output port, and at least one accessory module configured to receive power from the battery module. The accessory module has a second side with a second contour that mates with the first contour on the battery module, and has a power coupling connector and a fastener. The accessory module is interchangeably mateable with the battery module with the first and second contours nested together, and with the power output port engaged with the power coupling connector and with the fastener engaged with the mounting port, so that the battery module and the accessory module form a single integrated and substantially rigid structure.