The professionals and cons of EV batteries that absolutely cost in 5 minutes
Israeli company StoreDot recently announced that it can now mass-produce batteries for electric vehicles that can be fully charged in just five minutes. “The bottleneck in extra-fast charging is no longer the battery,” said the company’s managing director. But is this fast-charging battery really a game changer? And if so: exactly how?
Electric vehicle charging speeds are a minefield and can be difficult to understand. The latest models report peak charge rates in excess of 900 mph, but the average rate when charging 10% to 80% of the battery capacity is usually around half. The last piece of the battery is surprisingly difficult to “stuff”: Beyond 80% and outside of normal operating temperatures, fast charging slows down dramatically.
Even if you understand the capabilities of your car and its battery, the capacity of the charger itself will also limit the charge rate. In the UK, for example, there are only a handful of what we now consider “ultra-fast” chargers that can deliver over 100 kilowatts.
Most people drive well under 50 miles a day. With modern electric cars that can travel more than 200 miles on a single charge, they only need to be turned on once or twice a week. For around 60% of households with off-street parking, this can be done overnight outside of peak hours. Even if you feel like driving the full length of the UK from Land’s End to John O’Groats, today you can do so with a 30-40 minute break every 2-3 hours.
For those who can’t top up at home, there are already other options like topping up at work or quick topping up during your weekly business. There is little doubt that we could introduce electric vehicles without such high charge rates, but that depends on behavioral changes when it comes to “refueling”. Five minute charging removes a perceived barrier for many and makes the adoption of electric vehicles much easier for those without access to home charging.
Another major advantage comes from longer journeys. Few people currently own electric cars, so it is rare for fast chargers to be occupied on the go. However, this is likely to change over time. Tesla drivers leaving California for Thanksgiving can already wait hours for chargers. Will similar bottlenecks arise around the world when the rest of us catch up with the first Silicon Valley adopters? Charging for five minutes would reduce the number of fast charging points required at a gas station by a factor of ten, which would probably also improve economy, since fast charging points are expensive. The hardware alone costs tens of thousands of dollars.
Higher charge rates may not necessarily mean the need for larger network infrastructure at the charging hubs, as fewer cars would be charging at the same time. However, StoreDot claims to add 300 miles of range in five minutes, which suggests charging rates are approaching 1 megawatt, three times the rate of the fastest chargers available today. This is a significant drain of electricity and so it is unlikely that you will find such chargers on every street corner or at every existing gas station. The necessary substations and cables etc. are just not there. Such high charging capacities also require a new design of the vehicle connector and potentially cooled cables, which are bulky and difficult to handle. Perhaps wireless charging needs to become the norm.
Can the network handle super-fast charging?
Electric vehicles can overload local grids and sudden increases in demand can cause problems for power producers. When cars are mainly charged overnight or during the day using slower chargers, as is currently the case, these problems are relatively easy to deal with. However, when high-speed charging means commuters power their cars on the way to and from work, that concentrated demand for electricity coincides with existing peaks in demand. As intermittent renewable energies become more prevalent, this could cause major problems for grid operators as no one can order the wind to blow or the sun to shine in comfortable morning and evening blasts.
Electric cars pose some problems for intermittent renewables. Pedrosala / Shutterstock
Currently, electric vehicles are seen as a potential means of handling this disruption through controlled charging and even through the vehicle-to-grid, which allows car batteries to feed power back into the grid during periods of low generation. Widespread adoption of fast charging instead of home and work charging would reduce the capabilities for this type of system management.
Rapidly charging batteries can also reduce the environmental impact of cars and other battery devices. For most drivers who only make long journeys occasionally, a car with a smaller, lighter battery that is also more efficient and cheaper may be more appealing because charging stops are less inconvenient. This could have a positive impact on other battery uses as well: Maybe you don’t need two batteries for your power tools when you can charge in just a minute?
Ultimately, this could mean that fewer batteries are needed and therefore less environmental damage is caused by the extraction and manufacture of the materials. While the five-minute charge isn’t a complete game changer, it does make the transition to electric vehicles easier.
This article by Rachel Lee, PhD Student, Electric Vehicles, University of Sheffield, and Solomon Brown, Lecturer in Chemical Engineering, University of Sheffield, is republished by The Conversation under a Creative Commons license. Read the original article.
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Published January 31, 2021 – 10:00 UTC