A battery pack including a plastic protective layer bonded to the surface of a cell by spreading over the surface of the cell a polyurethane emulsion having a reaction product obtained by emulsifying and dispersing an intermediate product produced from a compound A made of an organic diisocyanate, a compound B1 made of a polyol mixture having not smaller than at least 2. The conveyor belt includes carrier plates which are movably connected to each other. Optional leggings, extending as high as the knee, can be provided as a removable or permanent part of the footgear.