There was a time when people’s biggest concern was choosing between diesel and petrol cars. Later, hybrids entered the scene, followed closely by plug-in hybrids. Then, electric cars started being a part of the discussion, prompting the question – is an electric car suitable for me? This is a question that remains unanswered, even over a decade after electric models started selling.
Now, however, the focal point has shifted to the specifications of electric cars. With the reduction in prices and a slight increase in ranges, the question has become less about whether to buy an electric car, and more about which kind of electric car to buy.
It must be noted that there is more than one variation of electric cars, specifically in terms of the battery. Despite electric motors being fairly uniform at present (until technologically advanced axial-flow motors or in-wheel motors become prevalent), the distinguishing feature is the battery.
Lithium-ion batteries are prominently used in the current electric vehicles. These batteries can be classified into cell, prismatic or pouch types. Cell batteries, which bear an uncanny resemblance to common AA batteries, can provide enough power to operate a Tesla if arranged into a sizeable battery stack. Pouch cells resemble small tinfoil bags, whereas prismatic cells look similar but are more costly to produce.
Regardless of their shape, these batteries function on the same fundamental chemistry, using a nickel-manganese-cobalt (NMC) anode (negative terminal) and cathode (positive) to facilitate the flow of lithium ions through the battery. The flow in one direction charges up the battery; the flow in the opposite direction generates an electric current to a motor, propelling the wheels.
What are the advantages of a lithium-ion NMC-type battery?
The chemistry is well-known (it’s the same basic principle found in your laptop or mobile phone) and the models have improved over time. If you construct a large enough lithium-ion battery, you can achieve remarkable ranges on a single charge, like the new Volkswagen ID.7, which can theoretically cover almost 700km in one go (under ideal conditions, etc) with its largest 83kWh battery pack.
But what are the drawbacks?
Although lithium-ion batteries are still commonly produced, they come with a host of drawbacks. They are costly to manufacture, although recent trends have shown a decrease in price. Their production involves heavy extraction of rare metals and minerals from the earth. This is not only a labour and energy demanding process, but it also raises human rights, child labour and political issues, with China predominantly controlling the lithium processing market. Moreover, these batteries add notable weight to vehicles, negatively impacting their efficiency. There’s also a risk of ‘thermal runaway’ or fires that are challenging to put out in case of any damage.
But is there a superior alternative? The answer is yes. The lithium-iron phosphate batteries or LFP batteries appear as a promising option. These batteries are increasingly becoming more prevalent for they offer some notable benefits over lithium-ion variants. For a start, their production is less costly, and they don’t require mining some of the harder to extract rare metals like cobalt due to their unique chemistry. The durability of these batteries is enhanced, with firms like BYD integrating them into the car’s structure to ramp up crash protection. They also possess a lower risk of experiencing thermal runway.
However, these LFP batteries do have a couple of drawbacks. They usually store less energy per unit volume, leading to decreased driving ranges. On another note, it’s worth highlighting that LFP batteries perform commendably against lithium-ion ones under actual conditions. But they pose more challenges in recycling, which may turn critical given the scarcity of lithium and other materials, especially when electric cars start becoming mainstream, necessitating the need for recycled batteries manufacturing.
One standout quality of LFP batteries is their resilience to constant charging up to full capacity, a contrast to lithium-ion batteries that should ideally charge up to 80% for optimal maintenance, only going up to 100% for extended trips. However, LFP batteries typically exhibit a slower charging speed than superior lithium-ion batteries.
As for the solid-state batteries, discussions around their implementation remain open.
In essence, the core of lithium-ion batteries is replaced by a solid, often ceramic in solid-state batteries. They come with a slew of potential benefits including enhanced reliability, reduced risk of thermal runaway, and super-fast charging. However, the challenge is in stepping up their mass production, so the earliest we might see a vehicle utilising solid-state batteries could be 2028.
For the majority of us, the speed of recharging a battery and hence, getting back on the road is paramount. Unfortunately, there’s no clear-cut answer to this. The most efficient charging systems, such as those by Porsche, Hyundai and Kia, operate on 800-volt energy, supporting over 300kW of DC fast charging. This could potentially allow a swift charge to 80% power in less than 20 minutes, beneficial for long-distance drivers, provided they can find and utilise a highly powerful charger, which are rather scarce.
The majority of other automobiles utilise 400-volt power, enabling charging up to 200kW of DC power. This typically signifies approximately 30 minutes to achieve 80% recharge, but that is subject to the charger operating at maximum power and the battery being at the right temperature to receive full power, neither of which are always a guarantee.
Which battery is right for whom? The answer is complex. A low-mileage driver might benefit more from a small LFP battery, whereas a lithium-ion pack that can charge at 800 volts would be more beneficial for a frequent long-distance driver.
Another important concept is kWh/100km. As we got accustomed to converting litres per 100km from miles per gallon, it’s now time to understand kWh/100km, with kWh representing kilowatt-hours.
The electric vehicle’s battery efficiency, much like a traditional vehicle’s fuel consumption, is rated on how quickly the vehicle dissipates its battery charge during transit. This efficiency rating is formally ascertained via the WLTP test, giving each car an officially sanctioned value.
However, the official figure of kWh per every 100km is only an optimal estimation, which is often derived from lab testing. The practical on-road experience may vary significantly.
How can you determine your car’s actual efficiency level?
The most impressive and streamlined electric vehicles on an average yield about 17-18kWh/100km when used in varying driving conditions, inclusive of some highway miles – which typically consumes most energy. If your journeys are primarily city-centric, you could marginally improve this figure to roughly around 15kWh/100km.
An exemplar case is the Hyundai Ioniq 6, whose aerodynamic design allowed us to achieve an average of 16kWh/100km primarily on motorway driving. Normally, figures beyond 20kWh/100km are deemed as relatively power-consuming, but anything surpassing 25kWh/100km could pose major challenges on extended trips.
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