Batteries: Why Different Materials Provide Longer Charges

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Batteries and Chargers: Why Different Materials Provide Longer Charges

Batteries have been used in some capacity for over a hundred years. The first rechargeable batteries of the modern era were lead-acid batteries, which are still widely used today. As batteries shrank in size, they found new applications and started changing different facets of our day to day life. Today, batteries are an integral part of our lives. Batteries are also an essential part of many industries. The automotive industry uses batteries in standard internal combustion engines, and cutting edge electric vehicles depend on them to move. Batteries are used in aircraft, to provide standby power for telephone exchanges, and to power every electronic device on the planet. Batteries are even used in space.

There are two main types of batteries that buyers should be aware of: rechargeable and disposable. Buyers should also know the different materials used in rechargeable batteries, and how they affect the life and charge of the battery. Finally, buyers should know where to purchase the correct batteries and chargers for their requirements.

Uses of Batteries

Batteries are used in any electronic device and in many electric ones. While most consumer batteries are interchangeable, batteries used for industrial devices are usually made to order, using the battery technology and materials that best suits the requirements.

Type of Battery

Characteristics / Application

Consumer batteries

General purpose consumer applications:

Cameras

Toys

Laptops

Radios

Energy batteries

For use in oil, natural gas, and solar applications

Industrial batteries

Deep cycle batteries

Used in industrial applications such as forklifts

Medical batteries

Life support systems

Hearing aids

Wheelchairs

Military batteries

Manufactured to military specifications

Transportation batteries

For use in aircraft, boats, automobiles, and electric vehicles

Stand-by / UPS batteries

Uninterruptible power supplies (UPS)

Emergency lighting

Alarms

Materials Used in Batteries

Disposable batteries and rechargeable batteries are made of different materials. In fact, there are several types of batteries in each category. Newer batteries are still being developed, with newer features. Some of the most common battery technologies are compared in the table below.

Name of Battery

Type of Battery

Characteristics

Alkaline

Primary / Disposable

Made of zinc and manganese dioxide

Effective in both high and low drain applications

Lead acid

Secondary / Rechargeable

Most common industrial battery

Uses lead and sulphuric acid

Low cost

Robust

Nickel cadmium

Secondary / Rechargeable

Long service life

High discharge current

Can withstand extreme temperatures

Environmentally unfriendly

Memory effect

Nickel metal hydride

Secondary / Rechargeable

Less toxic than nickel cadmium

Higher specific energy

Replaces nickel cadmium in most applications

Lithium ion

Secondary / Rechargeable

Commonly used in consumer electronics

No memory effect

Very good energy density

Slow loss of charge when not in use

Lightweight

Environmentally safe

Lithium polymer

Secondary / Rechargeable

Uses several cells in parallel

Higher discharge current capacity

Battery packs increase total available voltage

Battery can be shaped any way

There are numerous other types of primary and secondary batteries that use different materials. However, some of them are still in development while others are expensive and only used rarely. Some of these less common types of batteries are:

* Lithium sulphur battery

* Carbon foam based lead acid battery

* Potassium-ion battery

* Sodium-ion battery

The technology continues to evolve as scientists work to develop batteries with longer lives, higher capacity, and faster recharge times.

Deep Cycle vs. Standard Lead-Acid Batteries

Many batteries found in industrial settings are "deep cycle" batteries. Deep cycle batteries use the same technology used by standard lead-acid batteries. The difference is in how the batteries are optimised to provide different characteristics. Standard lead-acid batteries, or "starter batteries", have to provide a large amount of current for a short period of time. They are usually used to turn a car's engine over till it starts. Once the engine is running, the battery is no longer needed. Many starter batteries are never discharged below 80 per cent of their capacity. Deep cycle batteries, on the other hand, are designed to provide a steady amount of current for a long period of time. They cannot provide a current surge as high as starter batteries. However, deep cycle batteries can be deeply discharged (50 per cent is recommended) many times without adverse effects to the battery.

This difference in characteristics is created by using thicker active plates in deep cycle batteries, combined with higher-density active paste material, and thicker separators. The thicker plates resist corrosion as the battery is discharged and charged.

Factors to Consider When Choosing Batteries and Chargers

Buyers looking for batteries and chargers encounter numerous terms used to describe different features. A good understanding of these terms and features is essential to choosing the right battery and charger.

State of Charge

The state of charge (SOC) of a battery is a measure of the present battery capacity expressed as a percentage of the batteries total capacity. For example, a battery that has discharged half of its capacity would have a 50 per cent state of charge. Some modern "smart" batteries display their state of charge so users can quickly estimate how long the battery will last before a charge is due.

Memory Effect

Also called the "battery effect", memory effect is a feature of nickel cadmium batteries that causes them to hold less charge if they repeatedly recharged after they have only been partially discharged. This effect is only present in nickel cadmium batteries. Other forms of rechargeable batteries can be recharged after partial discharge without adverse effects. However, all rechargeable batteries gradually lose capacity as they age.

Capacity

The amount of charge that a battery can store is called its capacity. This is measured in amp-hours (Ah) or milliamp-hours (mAh). Battery manufacturers usually specify capacity as the constant current a new battery can provide for 20 hours. If the current drawn from the battery is increased, its capacity decreases.

Energy Density

Sometimes called the "volumetric energy density", the energy density of a battery is the nominal energy per unit volume of the battery. When combined with the energy consumption of a device, energy density can determine the battery size required for a given application. Energy density is measured in Wh/L.

Charge Rate and Discharge Rate

The charge rate of a charger is called its "C" or "C-rate". It refers to a charge or discharge rate equal to the capacity of a battery in one hour. For example, for a 2Ah battery, C is 2A. If the charge rate of a charger is marked as C/2, it would take two hours to charge the battery. A "C" higher than one (meaning the charger would charge the battery in less than an hour), require chargers that monitor battery parameters carefully to prevent overcharging the battery and damaging its cells.

When used to describe discharge rates, the same 2A battery discharged at a rate of 1C means that the entire battery would be discharged in one hour while providing a current of 2A. If the discharge rate is 2C, then the battery provides a current of 4A and discharges in half an hour.

How Different Materials Provide Longer Charges

The capacity of a battery, its charge, also depends on a factor called "energy density". Energy density is used to quantify stored energy, and is defined as the amount of energy stored in a system per unit volume. Batteries using different materials and technology have different energy densities.

Battery Type / Technology

Energy Density
(MJ per litre)

Energy Density
(Wh per litre)

Alkaline

1.8

250

Nickel cadmium

0.504

50 - 150

Nickel metal hydride

0.504 - 1.08

140 - 300

Lithium ion

0.9 - 2.23

250 - 360

Lead acid

0.34

60 - 75

Energy densities of batteries are constantly growing. In early 2012, a company called Envia doubled the energy density of lithium-ion battery packs by tweaking the material composition with the addition of silicon to the anode. Though many cutting edge developments like this one have not made their way into daily use yet, battery technology continues to advance.

Buying Batteries and Chargers on eBay

Buyers looking for batteries and chargers online can choose from a diverse selection on eBay. To begin looking, buyers can run a search from the search bar on the eBay home page. The search bar is available on other pages on the site as well. If a general search for batteries generates too many results, buyers can search for a specific type of battery by adding more specific keywords to the search term. For example, a search for " deep cycle golf cart batteries" returns a list of fewer, but more relevant results.

Lists can be narrowed down even more by selecting different criteria including the price range of the battery, its condition, and even the location of the seller. When buying on eBay, buyers must review a seller's return and exchange policy. This is useful in case the battery or charger does not meet expectations or is defective. To reduce shipping costs, buyers can purchase items from sellers located within the vicinity and arrange for a local pickup.

Conclusion

Batteries are now an intrinsic part of our lives. They are used in cars, aircraft, portable devices, and as backup power sources for essential services. One of the first batteries every used was the lead-acid battery. This type of battery is still widely used in automobiles and industrial settings. Other types of batteries are used in electronic devices, medical applications, and even to power electric cars. These newer batteries use different materials and technologies to provide longer battery life, more current, and more charge cycles.

Since different applications have different requirements, some battery technologies are more suited to some applications than others. For example, lead-acid batteries are still the battery of choice to start an engine because they can deliver a short, intense, burst of current. The capacity of a battery depends on its "energy density". This varies based on the type of battery technology, and advances are still being made that increase the energy density of batteries. Buyers looking for different batteries online can choose from a large selection of batteries on eBay.

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