Electric cars are flying off the shelves. A few years ago, they were synonymous with innovation and advanced technology; a cutting-edge form of transport that only a fraction of the population could access. Now, they're becoming increasingly affordable for people, thanks to various government-organised schemes and competitive prices.


It is interesting to think that, although they seem to represent a recent technological breakthrough, electric cars are, in fact, much older. They were built around the same time and in parallel with traditional combustion engine cars. But their entry into the mobility landscape was delayed due to complications related to developing one of the essential vehicle components: the electric car battery.  


The development of electric car batteries was unstable for much of the 20th century. It was not until the early 1990s that we began to see the idea of a car powered by an electric battery as a feasible reality to be realised and incorporated into the current market. 


The reason? Mainly because of the batteries: life and autonomy were the most significant challenges to achieving a vehicle that could truly become the heir to the traditional motor car, and both characteristics seemed to be somewhat compromised. 


Fortunately, science has lent us a helping hand since then, and nowadays, we have more than one option for alternative energy to standard means of combustion. But how does a battery work, how many types of batteries are on the market, and are they dangerous?


What is an EV battery?


In an electric or hybrid car, the battery is the component that stores and releases energy in the form of electricity. Once sent to the motor(s), it is converted into mechanical energy and transmitted to the wheels, allowing the car to move. It works on the chemical principle of the flow of electrons between a releasing element (called the anode, or negative pole) and a receiving element (called the cathode, or positive pole).  


A third element in the process is represented by the substance in which this flow of electrons moves, known as the electrolyte. For most of the history of batteries, this substance has been in a liquid state - but recently, solid state batteries have been introduced. 


How many types of EV batteries are there?


There are five different types of batteries for electric vehicles on the market, and they are:

1. Lithium Li-ion batteries: Lithium batteries are the most common type used in electric vehicles. In fact, they are the most common type to be used in several fields: phones, tablets, e-bikes and e-scooters are all examples of things that use these batteries. 


The secret to their success lies in their energy density, which allows even compact and lightweight batteries to perform incredibly well. These batteries have a low discharge rate, allowing them to maintain a full charge for more extended periods than other batteries. They have significant autonomy, high energy efficiency and good high-temperature performance. 


2. Solid-state batteries: Solid-state electric car batteries are an evolution of lithium-ion batteries. They are also known as lithium polymer batteries. What distinguishes them from the first on our list is the substance in which the electron flow moves: no longer liquid, but solid. This makes it possible to increase the battery's energy density further, and thus, its range. 


3. Ultracapacitors: Otherwise known as supercapacitors or electrochemical capacitors, ultracapacitors have an unusually large capacity when compared to more common alternatives. They contain both a positive and negative electrode, but store energy electrostatically rather than chemically. 


Perhaps the strongest advantage of using ultracapacitors is their ability to be recharged a large number of times with next to no degradation, since no physical or chemical changes happen during a recharge. 


They store polarised liquid between the electrode and an electrolyte - as the liquid surface area increases, the capacity for energy storage increases. These batteries are primarily used in secondary storage devices in electric vehicles because they can provide electric vehicles with extra power during acceleration and regenerative braking. 


4. Nickel-metal hydride batteries: Nickel-metal hybrid batteries (NiMh) have been used extensively in the automotive industry, both in electric and hybrid cars. They use a metal alloy and a nickel cathode to function. Their greatest strength was their long-life cycle, which lasted from eight to ten years - higher than the other types. 


However, their performance is not the best. In addition, they were unfortunately plagued by the memory effect: in the event of partial recharging, the batteries gradually lowered their recharging capacity, consequently reducing the car's range. 


Moreover, their efficiency cost is high, generating significant heat at high temperatures. All traits make them less effective when we talk about rechargeable electric vehicles. The search for ever greater efficiency led to their gradual abandonment in favour of lithium-ion batteries, while these batteries are now only used for hybrid cars. 


5. Lead-acid batteries: Lead-acid batteries are the oldest of all: the first cars at the end of the 19th century already used lead-acid batteries. In them, a lead anode and a lead peroxide cathode are immersed in a substance containing sulphuric acid.  


Nowadays, particularly in electrical technology, lead-acid batteries are no longer widely used. It's safe and durable, cheap to manufacture, and reliable. However, its lifespan is relatively short, and it doesn't perform brilliantly at low temperatures - ruling it out of the EV world, where these are vital traits. 


How long does an EV battery last?


If you are diligent and put proper care into it, you will be able to prolong the life expectancy of your battery for far longer than you expect. The battery components of an electric car require far less maintenance than their fuel-driven analogues. For some measure, an EV contains about 20 moving parts to the 2,000+ found in the drivetrain of an ICE-powered car. 


So, there are less parts that could break and eventually need replacing. Also, with fewer fluids, such as engine oil, and the regenerative braking technology that reduces brake wear, there is simply less that drivers need to be worried about. Most electric car batteries can currently last between 10-12 years before they need to be replaced - this is according to current estimates. 


However, as with many components of older cars, the battery will eventually begin to degrade - gradually losing charging capacity over time. The average battery decline of a car is 2.3 percent per year, so it isn’t an obviously noticeable process. 


Despite this, most car manufacturers offer a five to 10-year warranty on their batteries or up to 62,000 miles driven warranty. For EVs, you can go to the respective manufacturer to check the health and status of your car’s battery, with a view on replacing it when it drops to below 85 percent: the recommended level you should do so at. 


Overall, what can we say about electric batteries and safety?


Electric car batteries go through rigorous tests before they are put on the market, since one of the most significant measures that a manufacturer has to take before releasing a car into the market is its safety. For this reason, electric cars are equipped with a large number of safety systems to attempt to counteract any issues that could arise. 


Since the emergence of EVs, many have expressed their concerns about the likelihood of a car’s batteries catching fire in the event of a crash. And while there have been events of this happening in the past, the number of cases are minimal. Each battery is protected from impact, being installed in a lower position that protects it from any possible damage caused by accident, which could lead to a fire. 


Another possible worry is related to the high voltage levels that course through the underbelly of an electric car - since this is where the batteries are traditionally located. But this isn’t something that would affect the occupants of the car, since they will never be exposed to the electricity. 


How much does it cost to replace an EV battery?


When it comes to electric cars, one of the topics in which there is more uncertainty and confusion is how much it costs to charge the battery in an electric vehicle. Although this is a relatively remote possibility - given the warranties that often accompany the purchase of an electric car - replacing it yourself can be expensive. 


A car's electric battery is built using rare materials - such as lithium - and sophisticated technology, making it an expensive component. A study from Book My Garage claims that the average cost of a replacement battery in the UK is £5,656.80 - but naturally, this is subject to change depending on the make and model of a car, in addition to the type and size of the battery. 


It’s expected that the prices of electric car batteries will come down over the next few years, given the emerging market trends have already started to bring the cost of replacements down over the last few years. Through the advent of modern technology and more sophisticated, longer-lasting batteries, they may continue to fall in the future.


Interested in purchasing an electric car? Karfu has a dedicated ‘Is an EV right for me?’ section for you to access - with a range of electric cars for you to scroll through if your answer is ‘yes’. Give it a go now! 

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Silvia Iacovcich 09/09/22