A hand tool battery includes a charging coil and a bridge rectifier. One end of the ear-hook device is provided with a ball-like protruded section, and the circumferential edge thereof has a recessed T-shaped slot, and the circumferential edge of the earpiece is appropriately provided with a mounting section with a protruded peg mounted at the inner wall such that the protruded peg can slide within the T-shaped slot. The upper shield layer is amorphous or microcrystalline, made of a NiFe or CoFe composition containing B or P, and deposited on the lower shield layer. Saturation of the data transformers by the injection of power onto the single pair is thereby prevented. Sets of hidden values and anomalous values are also defined.