Charging a battery using constant voltage and pulse

A battery charger comprising:

• a main control means, which controls pulse voltage charging and constant voltage charging of a battery based on the charging state of said battery;
• a constant voltage charging control means, which controls charging of said battery with constant voltage under control of said main control means;
• a pulse charging control means, which detects voltage of said battery and controls charging of said battery with pulse voltage based on said detected voltage under control of said main control means;
• and
• a charging means, which charges said battery by outputting pulse voltage or constant voltage after DC power has been applied under control of said pulse charging control means or said constant voltage charging control means,
• wherein said main control means controls the charging means to charge said battery with pulse voltage if pulse width of the charging pulse voltage outputted from said charging means is larger than a reference pulse width, while it controls the charging means to charge said battery with constant voltage if width of the charging pulse voltage is smaller than said reference pulse width,
• wherein said main control means controls the charging means to cease charging said battery with the constant voltage when said constant voltage of the battery becomes smaller than a reference constant voltage.