Electrochemical noise of Li-ion rechargeable battery was measured during its discharging via a constant-value resistor. Statistical analysis of the measured noise was carried out; its standard deviation, skewness, and kurtosis are evaluated. Dependencies of these quantities on the battery state of discharge are obtained. Frequency dependencies of the electrochemical noise power spectral density are calculated using Fourier-transform analysis. The obtained spectra were shown to possess classical fractional-power frequency dependence (1/f) over the investigated frequency band (10–1000 Hz). The dependency of the spectra slope on the battery state of discharge is elucidated. The spectra parameters are shown to change abruptly for a fully discharged battery. At that, the spectral density full level increased, as well as the frequency-dependence power.