Rechargeable Batteries

Rechargeable batteries are batteries  that can be used repeatedly by restoring to its full charge after discharge.  Rechargeable batteries can offer an economic benefit when used instead of one-time-use disposable batteries.

The battery is recharged by forcing current through it, when the chemical changes are reversed in the cells. The charge current from the battery charger depends upon the battery technology used and the capacity of the battery being charged. The charging current differs for different types of batteries. For example, the current required to charge a 12 volt automotive battery would be different from the current required to charge a Ni-Cd battery.

A battery charger charges a battery by forcing current through its cells, which in turn reverses the chemical reaction within the battery cells, returning them to charged conditions. The simple design makes a battery charger inexpensive. However, you would need to compromise on quality, when buying a simple battery charger. A simple charger would need longer time to charge a rechargeable battery, and if left for long, the battery might get ruined. It may also over charge your battery and destroy the battery cells.

Types of rechargeable batteries

Nickel Cadmium (NiCad )batteries are the most popular type of rechargeable battery, although they tend to suffer from “memory effect." They have higher performance due to high rate of energy discharge. Nickel Cadmium can deliver even power until nearly all of the battery has been used.

Nickel Metal Hydride batteries are the most advanced commercial rechargeable battery. NiMH batteries offer higher energy densities than NiCads and ast 40% longer than Nickel Cadmium batterie. This battery is generally much more environmentally friendly than Nickel Cadmium, since they do not contain heavy metals.

Lithium Ion batteries do not suffer from the “memory effect” at all. These batteries have twice the energy of Nickel Metal Hydride, although they weigh 33% less. This is especially nice for portable items, such as laptops and camcorders. Lithium-Ion batteries have quickly become the emerging standard for portable power in consumer devices.

Memeory Effect

asically,the "memory effect" means that if a battery is repeatedly only partially discharged before recharging, the battery will “forget” that it can further discharge. The best way to prevent this situation is to fully charge and discharge your battery on a regular basis.

It's also a good idea to iInvest in a good charger. NiMH batteries should not be charged in a NiCad charger, unless the charger is specifically made for both chemistries. Make sure the charger you get has good reviews and is well made.

And bBe sure to store your batteries properly. Do not leave your batteries in a hot car, or in humid conditions.

Types of a battery charger

When Ni-Cd batteries are charged, the voltage at the cells gradually increases as the cells get charged by the battery charger. The process goes on until the battery is fully charged, with the output voltage of the battery charger slowly increasing, subsequently coming down as the battery nears it full charge limit. If you were using an intelligent charger, this decrease in voltage would indicate that the charging of the battery is nearing completion, and the charger would shut down.

For rapid charging a rechargeable battery, there are fast chargers available which charge the battery rapidly without damaging the cells. These chargers would generally have cooling fans, which cools and maintains the cells in the battery to a lower temperature, and does not let the charging over-heat the battery elements. Fast battery chargers can also be left charging the battery over-night, even with those standard Ni-Cd batteries which do not have special control circuitry.

Pulse technology is also used to charge rechargeable batteries. The charger feeds the battery with a DC pulse current, which has a specified rise time, with controlled pulse shape, width, frequency, and amplitude. A pulse charger can charge any rechargeable battery, irrespective of the shape, size, voltage, capacity, or battery chemistry. Such batteries would include automotive and valve-regulated batteries.

The universal bus (USB) has also been used in charging a rechargeable battery. A USB cable specifies a 5 volt power supply, which makes a cable a right power source to charge rechargeable batteries. The adaptation can charge standard NiMH cells, and with custom NiMH batteries, with built-in USB plugs and circuitry, there is no necessity of a separate battery charger.