Everything You Need to Know About Batteries

Types of Batteries

Batteries today are used in a wide variety of devices. They are classified into two broad categories: Primary and Secondary. These two types of batteries create energy in much the same way. The difference is that in Primary batteries when the supply of chemical reactants is used up, the battery is spent. Secondary batteries can be recharged and reused. This is done by having their chemical reactions reversed by supplying electrical energy to the cell. This restores their original composition and allows them to be reused. However, due to dissipation of the active materials, loss of electrolytes and internal corrosion, these batteries can only be recharged a certain number of times.

Primary Batteries

The zinc-carbon battery which is also known as a standard carbon battery is used in many inexpensive AA, C and D dry-cell batteries. The electrodes are zinc and carbon. The electrolyte is an acidic paste. These batteries produce 1.5 volts.

Alkaline batteries are commonly used in batteries from companies like Duracell and Energizer. The electrodes are zinc and manganese-oxide. The electrolyte is an alkaline substance. These batteries also have 1.5 volts.

Disposable batteries are shipped ready for immediate use. They are intended to be used until they are drained and then to be discarded. They are most commonly used in portable devices that have a low current drain and/or are used intermittently. These devices include clocks and remote controls. Regular disposable batteries do not fare well in high-drain devices like digital cameras. However, as we shall see later in this tutorial, newer, more high-tech disposable batteries have been developed for high-drain applications.

Secondary Batteries

Secondary batteries are rechargeable.

Lead-acid batteries are used in automobiles. The electrodes are made of lead and lead-oxide. The electrolyte is a strong acid.

In nickel-cadmium (NiCd) batteries the electrodes are nickel-hydroxide and cadmium. Potassium-hydroxide is the electrolyte. NiCd batteries can deliver a high current and can be charged in short time with a high current, but they have one drawback. They suffer from a nasty disadvantage called memory-effect. When a NiCd battery is charged without being completely discharged, crystals grow in the battery. These crystals diminish the capacity of the battery and are difficult to remove. Click here to learn more about this subject.

Nickel-metal hydride (NiMH) batteries are replacing nickel-cadmium because they offer similar properties but do not suffer from the memory effect that plagues nickel-cadmiums.

Both nickel-cadmium and nickel-metal hydride batteries output 1.2 volts, which is slightly less than zinc-carbon or alkaline batteries. All rechargeable batteries lose their charge due to self-discharge. For example when not in use, nickel metal hydride batteries will lose 20% to 50% of their charge within six months due to self]discharge. Factors such as storage temperature can impact the self discharge rate.

Lithium-ion (Li-ion) batteries use lithium and carbon with an electrolyte. They have a very good power-to-weight ratio and fairly slow self-discharge rates when not in use, so they are often used in high-end laptop computers and cell phones.

Rechargeable batteries like NiMH batteries are usually shipped in a discharged state and need to be charged before use, but some pre-charged rechargeable batteries are now becoming available.

Specialized batteries

There are also several specialized types of batteries, both primary and secondary. Lithium-iodide batteries are often used in pacemakers because of their long life. Zinc-mercury oxide batteries are often used in hearing aids.