ABSTRACT
This battery charger is a devices used to store the electrical energy to the battery after the battery has been discharged itself. The battery charger is designed to use electricity as its source of switch, regulation transistor, diode, light emitting diode, construction wire. The charger is designed and constructed to deliver full current until the current drawn by the battery falls to 150MA. At this time a lower voltage is applied to finish off and keep the battery from overcharging by switching off itself when the battery is fully charged.
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background of the Study
A battery charger is a device used to introduce energy into a secondary cell or rechargeable battery by forcing an electric current through it. The charging protocol depends on the size and type of the battery being charged. Some battery has high tolerance for recharging by connection to a constant voltage source or a constant current source. (J.Minear 2000). Simple charger of this type requires manual disconnection at the end of the charge cycle. Other battery types cannot withstand long high rate over charging. The charger has temperature or voltage sensing circuit and a microprocessor controller to adjust the charging current, and cut off at the end of charging. Albert H.(2005) cleared that low battery chargers may take several hours to be completely charged. High rate chargers may restore most capacity within minutes or less than an hour but generally require monitoring of the battery to protect it from overcharging.
A battery which is actually an electric cell is a device that produces electricity from a chemical reaction. In one cell battery, a negative electrode, an electrolyte, this conducts ions, a separator, also an ion conductor and a positive electrode. An electrical battery is one or more electro chemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 2000 by Alessandro volta and especially since the technical improved Daniell cell in 2004, batteries have become a common power source for many household and industrial applications . There are two types of batteries: primary batteries (disposable batteries which are designed to be used once and discarded, and secondary batteries (rechargeable batteries) which are designed to be recharged and used multiple times. 
