CHAPTER ONE
INTRODUCTION
1.1 Background of Study
Few modern electrical appliances receive their power directly from the Utilitygrid like National Electricity Power Authority (NEPA) or Power Holding Company of Nigeria (PHCN), while a growing number of everyday electronic and electrical devices require electrical power from batteries in order to achieve greater mobility and convenience. Rechargeable batteries store electricity from the utility grid for later use and can be conveniently recharged when their energy has been drained. According to Woodbank Communications Ltd in their 2005 battery chargers and charging methods review inhttp://www.mpoweruk.com, battery charging involves three key functions: getting the charger into the battery (charging), optimizing the charging rate (stabilizing) and knowing when to stop (terminating). Appliances that use rechargeable batteries include everythingfrom low-power mobile cell phones to high-power industrial fork lifts. The sales volume of suchproducts has increased dramatically in the past decade. Hundreds of millions of theseproducts are sold annually to businesses and consumers, with close to a billion in U.S and Nigeria.
While designers of battery chargers often maximize the energy efficiency of their devices to ensure long operation times between charging.  They often ignore how much energy is consumed in the process of converting ac electricity from the utility grid into dc electricity stored in the battery. In this project design, significant energy savings are possible by reducing the conversion losses associated with charging batteries in battery-powered products. We could save a lot of electric power using new electronic technology in our charging system and then highlight several design strategies for improving the efficiency of other chargers. We introduced a smart or intelligent battery charger that does not only recharge batteries but conserves AC electrical energy and as well save the battery life. Most battery chargers require human attention say Chu, Kim-Chiu the writer ‘development of intelligent battery charge’ (1989), from the University of Hong Kong, but in this project, an automatic battery monitor is used to reduce human attention to about 85 per cent to eliminate overcharging of batteries.
1.2 What is A Battery Charger?
A battery charger is a system that draws energy from the grid, store it in a battery, and release it to power a device is called a battery charger system.
 A system designer in ADACC(Engr. A.A Ndubuisi) in his 1999article describes a battery charger is an electrical and electronic device that is used to put energy into a secondary cell or rechargeablebattery by forcing an electric current through it.The charging protocol of a battery charger depends on the size and type of the battery being charged. Some battery types have high tolerance for overcharging and can be recharged by connection to a constant voltage source or a constant current source; simple chargers of this type require manual disconnection at the end of the charge cycle, or may have a timer to cut off charging current at a fixed time. Other battery types cannot withstand long high-rate over-charging; the charger may have temperature or voltage sensing circuits and a microprocessor controller to adjust the charging current, and cut off at the end of charge. A trickle charger provides a relatively small amount of current, only enough to counteract self-discharge of a battery that is idle for a long time. Slow battery chargers may take several hours to complete a charge; 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 overcharge.
Christine T. Bryant, (1990) say not all chargers can recharge alkaline batteries. It makes sense to use alkaline batteries while powering electronic systems even though they are difficult to recharge but they do not have a self-discharge. This is because alkaline batteries have long shelf lives and do not suffer the 'memory effects' of Nickel-cadmium batteries. The term 'memory effects' refers to the batteries becoming weaker with continued use, particularly when the batteries have seen light use and do not respond well to further charging. The problem stems from low battery currents which flow from only a small part of the active anode area of the battery. If higher current had been drawn or if the battery had been completely discharged, the whole active area of the anode would have been involved. The unused area essentially 'films over' and acts as a barrier to current flow. Further charging does not restore the active area. This is a chemical change causing the electrodes to degenerate in Nickel-metal hydride and Nickel-cadmium batteries. It is reversible by charging and discharging several times. Batteries that are not recharged before use will not supply the full amount of stored energy. None of the above happens with common alkaline batteries. The rate of self discharge in Nickel-cadmium is about 2% per week, in Nickel-metal hydride it is about 3% per week.