A portable battery jump start having a case having soft sides and a soft top cover configured to be selectively closed and opened. The sides of the case are joined to one another by seams that may be taped to become watertight. A first seal is configured for selectively connecting the top cover to the sides. The first seal can include a waterproof zipper. A rigid insert member is disposed inside the case and defines a center compartment, a left compartment and a right end compartment. A battery is snuggly disposed in the center compartment. Each clamp in a pair of electrical clamps is connected to the battery by one of the cables in a pair of cables and stored in one of the end compartments. A control module is disposed in the center compartment and electrically connected to the battery so as to permit selective supply of electricity from the battery to the cables. The battery and control module are protected from impact by being surrounded top and bottom with various pads and around the sides by the insert member.