Are EVs too heavy?

ARE EVS TOO HEAVY?

light weight car

THE IMPORTANCE OF LIGHTWEIGHTING ELECTRIC VEHICLES

In June 2023, the Institution of Structural Engineers published a report suggesting that the weight of our cars is too much for many multi-storeys built in the 60s and 70s. Known for being heavier, EVs have been the first to be blamed ─ but is this fair?

It’s clear that cars have come a long way in design and development over the past 50 years. But while their safety, range, and ride have improved drastically, there’s something else that has increased too ─ their weight.

Looking at some of the most prevalent vehicles of the 60s and 70s highlights the increase in weight. The BMC AD016 was Britain’s best-selling car for more than five years and had a kerb weight of just over 830 kg. Other popular cars included the Ford Escort at 867 kg, and the estate Ford Cortina at 940 kg. So, what’s the comparison to modern vehicles?

CARS IN THE 2020s

Let’s consider last year’s most popular car ─ the Nissan Qashqai. Comparing petrol and equivalent hybrid models within the range, such as the Acenta Premium, shows a weight increase of approximately 250 kg with the partially electric version. The 1.3L petrol comes in at 1348 kg, versus the hybrid 1.5L version at 1612 kg. While the slightly larger engine will contribute to the weight increase, it’s clear that the battery itself ─ even for just a hybrid ─ adds up to the weight. And the Tesla Model Y, the UK’s best selling electric car, boasts a weight of 1980 kg, with 771 kg belonging to the battery alone.

But is it fair to place all the blame on electric cars? It’s worth noting that, while electric and hybrid equivalents are likely to be heavier, there are still plenty of larger petrol and diesel cars on the upper end of the scale. New Range Rovers typically weigh upwards of 2400 kg, and the trend towards larger vehicles in general is another important factor in the weight debate.

Therefore, making more lightweight vehicles is likely to become a growing priority ─ not just in achieving higher fuel efficiency, but also to support older and aging infrastructure.

BUILDING LIGHTER EVS

When it comes to electric vehicles, the battery is likely to be an area of focus. Simply opting for smaller batteries won’t do; this will only negatively impact the range of usability of the vehicle. Therefore, if we’re going to make EV batteries lighter, a more sophisticated approach is required.

One option is the implementation of regenerative braking technology. Regenerative braking allows the surplus energy generated by braking to be directed back into the battery. This improved efficiency can extend the EV’s range by ten to 15 per cent, and even higher in optimum conditions. Therefore, by implementing regenerative braking technology, it becomes possible to slightly reduce the size of the battery, without a huge effect on range.

To safely implement regenerative braking technology, a dynamic braking resistor (DBR) is essential. The DBR dissipates any excess energy in the system, such as that generated when the car is braking on a full battery. Providing a safe way of dispelling this excess energy is crucial to protect the electrical components in the vehicle and to prevent overvoltages.

In line with lightweighting measures, it’s therefore important to choose a compact DBR. Here at Cressall, we have a range of lightweight DBRs available. Our flagship EV2 resistor is just 15 per cent of the weight of an equivalent air-cooled resistor, making it an ideal choice for EV manufacturers seeking to cut vehicle weight with no loss to safety or performance.

While there’s truth in that EVs are typically heavier than their petrol equivalents, it’s clear that the trend towards larger cars in general has contributed to the strain being placed on our infrastructure. But with EV uptake only set to increase within the next few years, making them lighter must be a priority. Regenerative braking is just one example of a technology crucial to improving EV efficiency and weight ─ and with new technologies emerging all the time, it certainly won’t be the last.

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Overcoming EV regulatory challenges

OVERCOMING EV REGULATORY CHALLENGES

cabin heating electric vehicles

THE SOLUTION TO MEETING EU REGULATION WITHOUT IMPACTING PERFORMANCE

The end of the road for internal combustion engine vehicles (ICE) has been on the agenda for a few years now, with many countries on track to meet their own targets for final sale. But the rollout isn’t without its challenges. Here, Simone Bruckner, managing director of power resistor manufacturer for the electric vehicle (EV) market, Cressall, explains the resistor solution to ensuring EU-compliant braking systems.

According to the European Automobile Manufacturers’ Association, or AECA, of the 1.9 million cars registered in 2021, the number of diesel car registrations represented 66 per cent less than in 2017. In the same time period, battery and hybrid EVs experienced a tenfold increase. However, while electrification seems to be progressing well for cars, challenges remain in other vehicle categories.

THE REGULATION

EU regulation relates to any vehicle belonging to category M3 — vehicles used for the carriage of passengers, comprising of more than eight seats in addition to the driver’s seats with a maximum mass exceeding five tonnes. Typically, these are buses and coaches.

Regardless of how category M3 vehicles are fuelled, they must be fitted with a secondary or endurance brake to safeguard the vehicle’s ability to stop. Category M3 vehicles brake differently to cars, as they do not purely rely on their service brakes to slow down. Instead, they also use an endurance braking system, which enables the driver to reduce the speed, or descend at a nearly constant speed, without using its service brakes. The benefit of an endurance braking system is that it doesn’t overheat as quickly on long declines and reduces the risk of fade or failure of the service brakes.

In order to comply with regulation, vehicles must pass the ECE R13 Type -IIA test, which requires the vehicle to maintain a speed of 30 kilometres per hour (kph) for 12 minutes on a 7 per cent slope without using its service brakes.

THE CHALLENGE

In the past, passing this test has proven difficult for EVs. The technical issue comes when the battery is fully loaded. The vehicle’s endurance braking system works on a regenerative braking model, meaning that when the vehicle’s brakes are pressed, the kinetic energy is converted into electrical energy, which is directed to the EV’s battery to recharge it.

When an EV’s battery is full, the vehicle’s kinetic energy cannot be converted into electricity and stored, meaning regenerative braking is impossible, and the endurance braking system cannot operate. So in order to pass the test, it’s important to ensure the availability of sufficient capacity in the battery, or create a separate outlet channel for excess energy to be directed into to keep the system operational and ensure the vehicle can pass the downhill test.

THE SOLUTION

One solution to ensuring sufficient capacity of the EV’s battery is to fit a dynamic braking resistor that removes excess energy from the system and dissipates it as heat. This heat takes the form of hot water within the EV’s own, existing cooling system. Removing energy from the system in this way ensures that the endurance braking system remains active by providing an outlet for excess energy.

Typical concerns around the use of a resistor for this application centre around a possible negative impact on weight and cost. But Cressall’s EV2 water-cooled DBR is designed specifically for EV applications, providing the high reliability, mechanical simplicity and low weight required. The EV2’s unique patented design means it is typically ten per cent of the volume and 15 per cent of the weight of the inequivalent air-cooled DBR. It can also be integrated into a vehicle’s existing overall cooling system, removing the need for a separate cooling circuit, further reducing weight additions.

The shift away from ICE vehicles is well underway, and despite no solid targets for the end of the sale of ICE buses and coaches, their electric counterparts are proving popular in Europe, with sales expected to quadruple by 2030. But for uptake to have as much success as anticipated, it’s crucial for automakers to consider how to ensure their braking systems are compliant to keep the EU’s roads safe.

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Why are wind turbines being switched off?

WHY ARE WIND TURBINES BEING SWITCHED OFF?

POWER TRANSMISSION IS JUST AS IMPORTANT AS GENERATION

UK windfarms hit an all-time high in wind power last year, generating more than 80 thousand gigawatt hours (GWh) and enough power for over 22 million homes. Yet, reports also came out of wind turbines being switched off due to overcapacity — at the expense of customers.

Despite reaching impressive milestones in recent years, there’s a massive problem with the renewable — and particularly wind sector — power wastage. In 2022, it was reported that Brits paid millions to switch off wind turbines as networks were unable to deal with the levels of power generated.

The UK has set ambitious goals for renewable energy sources for the next few years, aiming for a more sustainable approach while reducing dependency on both fossil fuels and external suppliers. As the past 18 months or so have highlighted, the volatility of global markets means it’s essential that the country is able to secure its own energy supply.

Fortunately, the UK does have the natural resources to do so. With the greatest wind energy potential in Europe, it’s clear why wind power has been a preferred route for planners and developers to take. So why are wind turbines still being switched off, and why is this energy being wasted?

DISTANCE FROM THE GRID

Offshore wind farms are often a significant distance from the Grid. Typically, these farms are connected to the Grid with a specialist, individual cable connection through a converter and into the transmission network, allowing the farm to distribute power.

The issue with this setup is that the offshore system will typically have fewer connections readily available than an equivalent farm on land. Because of this, there are less options available when it comes to distributing power during surges or when there are problems with the on-land network.

DISTANCE FROM DEMAND

Furthermore, many of these wind farm installations are being built in remote areas of Scotland or in the North Sea, where winds are stronger. Though this is certainly positive when it comes to power generation, the issue is that the local area isn’t where the demand is.

More power is needed in the south of the country, far from where the electricity is being generated. And while the transmission networks can transport electricity great distances, without efficient connections and cable routes a lot of power can be lost before it reaches crucial areas.

A FOCUS ON INFRASTRUCTURE

It’s clear from these issues that improving power infrastructure is just as vital as delivering new power generation projects. Reassuringly, there are developments underway to address these issues. One such example is the ‘Eastern Green Link 2’ (EGL2), which involves the manufacture and installation of a high voltage direct current (HVDC) subsea cable from Peterhead in the North of Scotland down to Drax in Yorkshire.

A crucial element of these power transmission systems is the host of resistors within that help to facilitate the safe movement of electricity. Pre-insertion resistors, for example, can absorb and control transient magnetising currents within transformers throughout the network. This control helps keep voltages consistent with minimal dips, reducing potential disturbances for users of the power network. They can also help mitigate against temporary overvoltages, such as those caused by exceptionally strong winds.

Discharge resistors are another vital component, particularly in terms of safety. These can reduce the risk of sudden overvoltages from capacitors and inductors that have become isolated from their networks or in situations where an emergency shutdown is required. In offshore farms that are far from other connections, the inclusion of discharge resistors is essential in having a sufficient ability to remove excess electricity when required.

Implementing resistor technologies as new projects are built helps both to ensure safety from dangerous overvoltages, as well as safeguard electricity on the Grid from fluctuations and dips.

So, as the UK continues to invest heavily in the renewable energy sector, considering how we’ll transport this energy will be just as important as thinking about how we will generate it in the first place. With projects like EGL2 on the horizon, it’s clear that the industry is taking the right steps to secure a reliable network from the turbine all the way to our homes.

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Electrifying agriculture

ELECTRIFYING AGRICULTURE

HOW EV TRACTORS CAN SUPPORT THE SECTOR’S SUSTAINABLE SHIFT

The electrification of the on-road transportation sector is well documented. What’s less discussed, however, are the off-road applications that can also benefit from electrification. That includes agricultural equipment. Here‘s how the agricultural sector can electrify, and the echnologies that can help.

According to the UK Government’s Department for Environment, Food, & Rural Affairs’ Agri-climate report 2021, in 2019, agriculture was the source of ten per cent of total greenhouse gas emissions in the UK. The sector was also responsible for 68 per cent of total nitrous oxide emissions, 47 per cent of total methane emissions and 1.7 per cent of total carbon dioxide emissions.

However, despite these figures, it seems the farming community is seeking change. The 2021 Farm Practices Survey indicated that 67 per cent of farmers consider recognising greenhouse gases to be either fairly or very important when taking decisions about their land, crops and livestock. One method of reducing emissions is to electrify equipment that traditionally runs on fossil fuels, such as tractors.

A NECESSARY CHANGE

Modern agriculture depends on a fleet of heavy-duty vehicles, from pickup trucks and small utility vehicles to massive tractors and combines that can weigh several tonnes, plus attachments. This machinery is commonly powered by diesel engines, mostly due to their higher torque and dependability. And here is where an electrification challenge may lie.

The electric sceptics of the agricultural industry claim that the largest problem with electrifying tractors and other heavy vehicles is that battery-powered options don’t have the energy density of a diesel model required to do long, hard work in the field. As load impacts on battery life, pulling a piece of heavy equipment would drain power fast. Using diesel, therefore, means a farmer won’t have to worry about filling the tank for 10 to 12 hours while out on the job.

Battery technology, therefore, needs to be developed in order to withstand the heavy loads of agricultural vehicles and supply a lasting and reliable source of power. Some manufacturers have produced compact, swappable batteries to extend the length of operation. Another option, developed by John Deer in 2019, features a long power cable that’s only available for farmers who are able to produce their own electricity via the use of solar panels, manure digesters or windmills.

Right now, despite its challenges, attempts to electrify farming vehicles are well underway. The work is being done, and given the mounting pressure to decarbonise all areas of industry, it won’t be too long before electrification becomes more accessible to the masses. In addition to the battery itself, manufacturers must consider the other components that make electrifying possible.

DYNAMIC BRAKING

Resistors will play a role in electrification, to support the process of regenerative braking. As part of regenerative braking, excess kinetic energy is used to recharge an EV’s battery. It is able to do this because the electric motor in an EV can run in two directions: one, using the electrical energy, to drive the wheels and move the vehicle, and the other, using the excess kinetic energy, to recharge the battery.

When the driver lifts their foot off the accelerator pedal and steps on the brake, the motor starts to resist the vehicle’s motion, “swapping direction”, and begins putting energy back into the battery. As a result, regenerative braking uses the EV’s motor as a generator to convert lost kinetic energy into stored energy in the battery.

Regenerative braking can support the ongoing dilemma of electric tractor battery range. However, to work effectively, other technologies are needed to make the process safe and effective. If the vehicle’s battery is already full or there is a failure, regenerative braking cannot happen as the excess energy has nowhere to go and must be dispelled safely. If not dissipated, it won’t be possible to slow down the vehicle, resulting in braking failure. To make electrifying agriculture safe, resistors are used to collect excess energy and dissipate it safely.

Cressall’s EV2 dynamic braking resistor converts excess kinetic energy during the braking process into heat that can be dissipated or used in other parts of the vehicle, like to heat the tractor’s cabin. It is a high-power density, lightweight and compact resistor that has proven to meet all major shock and vibration standards, suitable for all automotive applications, not just on-road vehicles.

While electrifying on-road vehicles has become well recognised, the same attention must be paid to other areas of the automotive industry. The agricultural sector is beginning to wake up to the prospects of decarbonising, and positive steps are being taken towards electrification. To make it happen, agricultural vehicle manufacturers need to consider the technology that can make agricultural EVs more efficient, and safer.