An electronic time piece senses and warns the electric residue of a secondary cell having electrodes of conductive polymer to a user during the rapid charge. The electronic time piece converts a kinetic energy produced by the user's motion into an electric energy. The electric energy is then outputted from a power generator coil as a charging voltage for charging a chemical reaction type secondary cell. The charged energy in the secondary cell is used to actuate a time piece circuit for indicating the time. The electronic time piece comprises an electric residue sensor unit which outputs an electric residue detection signal when the voltage in the secondary cell continues to exceed a reference voltage corresponding to an electric residue in the secondary cell for a predetermined time during the rapid charge.