Batteries, or dry cells are manufactured to supply steady and uninterrupted D.C power to different modern day gadgets that run with electrical energy. Batteries are generally lead-acid cells. Over 15 billion are produced every year and are sold worldwide. Many of these are alkaline-batteries which are discarded after being used for a single time. But there are also some which can be charged again and again after every use and are known as "rechargeable batteries". These should be kept at fully charged condition so as to meet the D.C. power demand whenever needed. Therefore suitable battery chargers are required to charge those types.

The different types of battery chargers are:

1) Medical

2) Automotive

3) Commercial

4) Industrial

These may be stationary or portable.

These rechargeable batteries are of high capacities. Rechargeable batteries, like Nickel-Metal Hydride (NiMH) or Lithium-ion (Li-ion) batteries can be charged several hundreds of times and last far longer period in high drain devices.

By using these repeatable charging batteries people can save tons of money. When the charge goes down below a certain level it stops supplying D.C power to electrical instruments, then the battery needs to be charged to regain its capacity of supplying D.C power. Low quality chargers can even damage batteries and shorten their lifetime. The charger takes current directly from electric lines and induces the electric charge into the batteries.

The charging of these depends on different factors such as its capacity, its age, its initial charges, etc. Different chargers vary widely in this matter. There is a tendency of generating heat during the charging of rechargeable batteries which is one of the most commonly cited factors for the damage of these battery. The heat mainly generates due to the internal resistance and chemical reaction of the rechargeable batteries. Excessive current can also damage the battery after it is fully charged.

There are some automatic chargers which initially charge at a very high rate and continuously monitor the cell voltage to reduce or shut off the charging when the battery tends to charge fully. The battery chargers can take 1 hour to 8 hour of time for charging depending upon the design and ratings of these chargers. There are also different visual indications like LED on the battery chargers. These indicators indicate that the rechargeable type batteries should

not get overcharged and help them preventing them from overheating.

Nowadays there are wide applications of rechargeable styled batteries. These types are even used in power generating stations as a substitute of D.C current and emergency Lighting System. They are also used in vehicles like cars, trolleys, bus, etc. There are also some battery driven cars which run on streets completely based on battery-power and not on fuel.

The use of rechargeable batteries can also be found in laptops, IPods, cellular phones, electric wheelchairs, etc. Therefore suitable chargers are essential for the charging of these re-chargeable batteries.