Most electric car owners don’t have to worry that repeated fast charging during long-distance driving will damage the battery; unfortunately, the problem with chronic range depreciation from prolonged high-speed highway cruising isn’t going away. Article's in the Financial Times aired the issue of a Nissan Leaf driver who used highway fast-chargers up to 4 times with dire consequences for the battery. This was an unfortunate penalty for Nissan’s early lead in the development of battery power. Its technology choice of air cooling doesn’t appear to be an issue for most of the latest battery-only sedans and SUVs. David Greenwood of Britain’s Warwick University points out that the design of the Leaf, with a relatively small and inexpensive battery, makes it ideal for commuting. Its limited cooling ability though does make it susceptible to overheating and multiple fast charging, unlike the battery technology in more expensive vehicles like Teslas or the Jaguar I-Pace with active battery cooling which can easily handle fast charging. But a damaging shortcoming for electric cars remains high-speed cruising, the problem that dares not speak its name. I’ve yet to read from a manufacturer that there might be a substantial range penalty for prolonged legal fast-lane cruising in an electric car, although there are plenty of claims that exaggerate battery capacity's sometimes by more than 30%.
British expert Nickmolden, chief executive of Emissions Analytics, agrees that indicated 80 mph cruising speeds, the norm in Britain, generate significant range penalties. Potential buyers of electric cars are not made aware that as soon as they consistently raise their speed over 60 mph, range begins to drain away, and in mainland Europe often with a 130 km/h (81.25 mph) speed limit it will disappear at an alarming rate. In Britain, the speed limit is 70 mph on motorways, and in the real world this becomes about an indicated 80 mph and no doubt a similar leeway is practiced in Europe, except in Germany of course where big chunks of the motorway system don’t have a speed limit at all.
My own data shows that most modern electric cars, driven on motorways at speeds close to 75 mph, will shed range at just over 30% compared with the range availability on offer. In other words, if the range availability is 100 miles, don’t expect to go much further than about 65 miles. Some models like the Nissan Leaf 62 kWh, Fiat 500e 42 kWh, Vauxhall Corsa 50 kWh and Polestar 2 78 kWh won’t get you 50% of the way.
Professor Greenwood points out that electric car drivers operate under varying conditions which will generate different performances, while hot or cold climates can undermine performance.“Electric cars are much more energy efficient than ICE (internal combustion engines), and that efficiency is relatively constant over the entire operating range. What this does mean is that the range will be much lower at high road speeds than it is at low road speeds – simply because it takes more energy per mile at high speed than it does at low speed due to the aerodynamic drag of the car increasing with speed,” Greenwood said in an email exchange.
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