Fast Charging: Why not rely on advertised power and which electric cars (really) are the best?

A new power has been added to the technical sheet of electric vehicles: the power of rapid charging. Enough to create a hierarchy between models, this value is sometimes abstract, and can be misleading. explanations.

To attract customers, manufacturers have long put forward technical papers for their cars. And in particular, the maximum power of the engine, which generally makes it possible to roughly predict the level of performance of the model, but also to establish a hierarchy between them. But depending on the mechanical configurations, and thus the mechanical power distribution, two cars of the same caliber may not present the same character. Nothing would change the face of the world in and of itself, whether for heat or electricity, when we talk about peak energy.

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If electric cars always have the maximum power always communicated by the manufacturers, the administration distinguishes the latter from the maximum net power, which is also called the nominal power. More specifically, it is the power produced by the traction chain (motor(s) + battery) for 30 minutes, which is indicated in box p2 on French registration cards. They are generally very far from peak power due to electrical technology: we generally see a difference of about 50% between the two values. The proof is with Volkswagen ID. Buzz, the latest novelty tested by us, which then delivers on its gray card – which we always check – with a nominal power of 70 kW (95 hp) instead of a peak 150 kW (204 hp). This is also observed with the Tesla Model Y Performance, with 155 kW (210 hp) instead of 312 kW (424 hp), as revealed by the official documentation in our possession.

Modest recharge powers are best

But electric cars have added a new feature to their data sheet that could serve as a sales argument on its own: fast charging power. If it’s timidly associated with a recharge time of 80%, the value being dialed is no less than a peak located somewhere on the curve. But unlike the power of a car, there are no rules. And this is the problem, as there are differences between the declarations and the authority that is delivered during a certain period. Hence this article.

During the supertests, we decided to test each vehicle in different cargo exercises, varying station type and grids. This is in order to obtain maximum data and understand what is hidden under the electrical floor. Thus, we assign for each car an average charge power of between 10 and 80% charge, depending on the standard curve used. Faced with notable differences, we calculated the differences between the performance suggested by the stated peak, and the average power actually available on a full useful tank. And as always, there are good surprises and lesser surprises. Even the very bad.

Because no, a higher peak charge won’t necessarily allow you to leave the station faster to get the equal amount of power the station provides. It is still necessary to maintain this energy, at best, throughout the loading exercise. This is what electric cars can do at the lowest levels of power. And so they find themselves on the podium with three models under 100 kW announced in order, along with the Kia Niro EV, IWIZ U5 and MG5.

The triumph of the Korean compact SUV which, despite declaring 72 kW, manages to maintain an average power of 65 kW. navel? Noticeable peak power that is higher than the advertised peak. But also a better maintained curve as we’ve seen during ultra testing. The Aiways U5, which is slightly faster at reloading, escapes with a -11.1% difference, while the MG 5 ranks third with a -14.9% difference between its peak value of 87kW and its observed average of 74kW. With lower power, the batteries are less stressed. This allows them to maintain a more or less flat curve or, at worst, to present a ladder with distinct, steady steps.

The paradox of high DC powers

Obviously, the cars with the most powerful powers that have been announced have struggled to make it happen: among the last five cars, three give hope for rapid recharging with more than 200 kW! Two reasons explain this phenomenon. On the one hand, it is sporty: with high starting values, the differences go up very quickly. Which is why the new Tesla Model S Long Autonomy, which we were able to measure exclusively, is among the worst students (-42.40% difference). However, its charging curve is pleasing with a power of 250kW that is kept for about 7 minutes, up to a 40% charge rate.

But on the other hand, it is technical, not all cars are able to maintain such high power for a long time, whether due to technical limitations or by choice in order to preserve the life of the batteries. The fact remains that it is the Tesla Model Y that wears the cap on this ranking: proudly declaring a peak of 250 kW, the SUV finally delivered a ‘nominal’ 105 kW of power in our hands. This corresponds to a difference of – 58%, significantly higher, behind the BMW i4 eDrive40 (- 43.4%). Their common point? An early temper, with a curve that puts the pack at the start of a workout and not for long enough.

A character shared with the Ford Mustang Mach-E, which displays the same curve profile. But with an official peak of 150 kW, this American SUV limits the difference to -34%. Obviously, the stronger the force, the more endurance the curve lacks. The Renault Megane e-Tech is an exception here, but it confirms that, as the famous slogan says, “Without mastery of strength, nothing.”.

Hyundai Ioniq 5 and Nissan Ariya both live up to their promises

However, the Nissan Ariya, which shares its CMF-EV technology platform with the compact, is very different. All month long in its 87 kWh version, its performance was remarkable. It looks good with a difference – 18.5%, and it also manages to climb among the best averages with its 106 kW. And remember, the Japanese SUV was never able to exceed 115 kW, against the promised 130 kW, which might have earned it the first place in this ranking. That spot is occupied by the Hyundai Ioniq 5, which is heaping praise: Its average charging power of 176 kW is highest in the rankings, and it doesn’t deviate much from the promised 220 kW peak. These are the two cars that best combine absolute (nominal power) and relative (difference with declared numbers) values, while the Aiways U5 has nothing to be ashamed of with its third-place finish in the points tally.

By this post, it’s the Tesla Model Y that disappoints the most, with charging performance that peaks at 250kW that is ultimately just a smokescreen. This puts it at the bottom of the battle, between the Volkswagen ID.3 and the MG ZS EV, when evaluating the overall image. The Renault Megane e-Tech is also at the bottom of the ranking, with a low average power and a very large gap.

Towards a fast nominal charging capacity to better guide buyers?

If the electric motors power calculation is strictly specified by the regulations, the charging power is not subject to any consideration by the management. An unfortunate choice, because the values ​​declared by manufacturers can mislead drivers. The latter would no doubt be more tempted by the reassuring maximum values, rather than the recharge time from 10 to 80% within a certain period which has no real value in the end: a Peugeot e-208 that requires 27 minutes to fully achieve its 10 does not recharge to 80% as fast as the Tesla Model S Grand Autonomie, which needs exactly the same amount of time for the same workout. Even worse, they may never see the advertised power color depending on the cars and the charge rate when plugged in.

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There is currently no bill that requires manufacturers to deliver charging medium power. Because if motors are already subject to several influencing factors, which has prompted some manufacturers to put their reservations on paper, fast charging is much more sensitive: it depends on the charging rate when plugged in, the outside temperature and the temperature of the battery. , or the electrical network. For the same vehicle, charging performance can change rapidly from one station to another.

In any case, vehicles with more modest powers seem to deliver on their promises best. On the other hand, there’s a good chance drivers will get less money with cars that have the highest advertised power.