The improved method of the present invention comprises charging a vented alkaline electrolyte-containing electrochemical cell employing an electrode pair selected from the group consisting of nickel-zinc, nickel-cadmium, silver-zinc and silver-cadmium and at least periodic measuring the charging efficiency of the cell by determining the rate of gas evolution from the cell. The charging of the cell is terminated when the charging efficiency substantially decreases, signifying the cell having reached an about full charge. The charging efficiency at that point normally substantially decreases to a value of about 0.5.+-.0.2. In the alkaline electrolyte-containing cells, the charging efficiency is determined according to the formula E=1-(15.8/I) v wherein E is the charging efficiency, I is the current in amperes and v is the gas generation rate in the cell in cc per second. The improved method prevents overcharging of the cell and accurately determines when an about full charge is reached. Accordingly, charging can be carried out without risk of damage to the cell and with the greatest efficiency.