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Understanding Battery Construction - A Handy Reference Guide

Understanding Battery Construction - A Handy Reference Guide

01/07/2016

In the modern world we use batteries in a variety of ways to power a whole host of different things. However, it isn’t just a case of one battery type does every job – far from it in fact. Each electrical device, appliance or piece of machinery that uses battery power requires different types and sizes of batteries with different chemical components that do a specific job.

While this may sound like an obvious point as most of us will know that the slim line battery in a Smartphone or laptop is in no way going to be able to start and run your car, many of the basic principles behind a battery are the same across the board. A battery’s main purpose is to provide electrical power, which, depending on the battery type, can be used to power devices or to store excess power generated.

As battery experts, we’re looking to give you a better insight and understanding into some of the more common everyday batteries you may come across or need, whether it’s a lead-acid car battery or leisure battery, or a compact lithium battery. This should help you decide on which is the best type of battery for your requirements, both in terms of efficiency and cost.

Lead-acid batteries

Lead-acid batteries have been around since 1859 when they were first invented by French scientist, Gaston Planté. Planté created the first version of rechargeable battery, which were heavily developed in the 1980s into valve-regulated-lead-acid (VRLA) batteries that were sealed and used in many different applications, such as car starter batteries, marine batteries and leisure batteries, to name but a few.

In laymen’s terms, the lead-acid battery works by using a chemical reaction between lead and sulphuric acid to create an electrical current that powers an application. The process is then reversed which allows the battery to recharge. A lead-cell battery consists of a positive and negative electrode made from lead that are then submerged in the sulphuric acid solution that becomes the electrolyte to create a chemical reaction in the liquid that is converted into electrical energy.

With the innovation of technology over the past 150 years or so, the lead-acid battery has been revolutionised and honed to meet modern-day requirements and is still one of the most affordable, effective and common choices for powering motor vehicles. The standard lead-acid batteries use sulphuric acid in liquid form and are often called flooded or wet-cell batteries. Due to the nature of their contents, which are highly toxic, they can be hazardous to transport and use as they must be kept upright.

This is where new developments were made to provide a safer, more versatile battery in the form of gel and absorbed glass-mat (AGM) batteries that are often used in more niche roles like large back-up battery power for mobile-phone masts, hospitals and power systems that may not have access to mains power.

Absorbed-glass-mat (AGM) batteries

During the 1980s lead-acid batteries underwent much development, and this is when the absorbed-glass-mat or AGM batteries hit the market. Unlike the traditional flooded lead-acid batteries, which were known to require significant maintenance and came with safety issues due to the fact they used liquid sulphuric acid, the AGM were designed to be low maintenance, lightweight and mounted in any position. This makes them ideal for use in aircraft, vehicles and Uninterrupted Power Supply (UPS) systems.

While the chemical reaction and components that use lead and sulphuric acid to create an electrolyte are the same, there are differences in how they work in comparison to the standard lead-acid battery. The make-up still consists of lead electrode plates and sulphuric acid, but the acid electrolyte solution is absorbed into a fibreglass mat, hence the name. This is where the chemical reaction takes place, rather than in pure liquid form. This allows them to be used in numerous portable applications, such as car and leisure batteries, as there is no risk of the toxic lead-acid liquid spilling or leaking out and they are completely sealed, so require very little maintenance.

Other advantages of using AGM batteries over standard lead-cell batteries are that they charge much faster than flooded-cells and are able to deep cycle, which means they can provide a lower power supply over prolonged periods of time and have a better depth of charge for a longer charge cycle life. This makes them the ideal solution for leisure batteries and back-up batteries, where a power supply is needed for extended lengths of time.

Gel batteries

Similarly, gel batteries, which are also VRLA lead-acid batteries, act in a similar way to AGMs. They also offer a safer battery power solution for mobile applications, as the sulphuric acid liquid required to make the chemical reaction that generates electric energy is immobilised. This means that they can be mounted in any position and don’t need to be kept upright like standard flooded-lead-acid batteries.

The immobilisation of the sulphuric acid is obtained by adding silica to the solution, which turns the liquid into a paste or gel inside the battery seal. This gel surrounds the lead electrodes inside the battery cell and allows the chemical reaction to occur. But one of the distinct advantages of using gel batteries over flooded-cells is that they significantly reduce the evaporation of the electrolyte and corrosion problems that can occur with the liquid lead-acid batteries. They are also a lot more robust and resistant to vibrations and shocks, which makes them more suitable for a number of different uses, such as portable electronics and UPS systems for computers.

Why use AGMs and gel-cells over standard lead-acid batteries?

The standard-flooded lead-acid battery is on the whole cheaper to manufacturer, therefore making it a more cost effective choice. However, it can be limited in its use as it needs to be kept upright and often requires more maintenance. This is due to the fact that with wet-cells the water inside the cell evaporates during the chemical reaction process, which over time will need topping up. But with gel and AGM batteries, the evaporation is minimal therefore they require very little maintenance over a long period of time.

Furthermore, the AGM and gel-cells don’t need to be kept upright in order for them to work and are designed to be spill-proof, which means they can be used in a much broader range of applications that includes boat and marine batteries.

Lithium batteries

Another choice for secondary, rechargeable batteries is lithium or lithium-ion batteries. However, these are generally used in portable electronic devices such as mobile phones, laptops and other home electronics that require battery power.

Despite its weight, lithium metal has one of the largest energy densities and electrochemical potentials, which made it a viable choice for use in batteries. However in its metal form, there were inherent safety issues with its stability. This is when scientists looked to utilise lithium-ions (the non-metallic form of lithium) instead, which enabled them to create a lightweight, high performance rechargeable battery that could also provide compact designs suitable for the latest advances in electronic devices.

They have been around since the early 20th century, but they didn’t really hit the forefront until the seventies when the first non-rechargeable lithium batteries hit the commercial market. However, it wasn’t until 1991 that the Sony Corporation released its first lithium-ion rechargeable battery, which revolutionised the world of electronics.

One of the other great advantages of lithium-ion batteries is that unlike nickel-cadmium that was the other common alternative; they offer a higher cell voltage, lower maintenance and don’t require an initial full charge or frequent recharges to maintain battery life. This makes it the perfect choice for electronic devices and appliances, but it is also becoming a common replacement for electric powered golf buggy batteries and utility vehicle batteries, as they are more lightweight that lead-acid cells, but supply the same voltage.

It’s fair to say that there is a battery for everything, whether you want an independent power supply for your touring caravan, narrow boat or mobile phone. Modern batteries in all forms are now designed with greater efficiency, lighter weight and longer battery life, so powering all kinds of applications is possible. They can even be used for storing energy and are becoming a widely used in the renewable energy industry to store solar and wind turbine energy to deliver a constant supply of electricity.

At Alpha Batteries, we offer an extensive range of standard lead-acid, AGM, Gel and Lithium batteries for an assortment of uses. As experts in our field, we’re on hand to help you make the right selection for battery power that will last the duration.