What's the deal with 300 kilowatt fast chargers?

When GOFAST introduced Switzerland’s first 150 kilowatt public fast charging station in August 2016, it was (quite rightly) celebrated as a milestone for electromobility (read article). At the time, hardly any vehicles were capable of taking advantage of the full potential on offer at these charging stations, and it was generally believed that 150 kilowatts would remain the optimal solution in terms of output and commercial viability for some time to come. Nowadays, however, charging station manufacturers are vying to outdo one another with ever higher output figures in excess of 300 kilowatts. Manufactured by Swiss company EVTEC, the devices GOFAST has introduced in Würenlos deliver a world-leading 384 kilowatts. ABB also recently launched a new fast charger in this performance category. GOFAST is staying true to its credo that charging should never be limited by the available infrastructure. In this article, we explain what this development means and, in particular, how it will benefit electric car drivers.

Is this the end of the road for 150 kilowatt fast chargers?

Along motorways, 300 kilowatt fast chargers offer tangible benefits – even if the high charging power is, in reality, only drawn on by a handful of models and, so far, rarely under everyday circumstances. The peak power drawn from GOFAST currently averages just 50–60 kilowatts. However, installing 300 kilowatt HPC chargers offers charging network operators the opportunity to provide sufficient power per outlet with fewer resources and lower costs. Even with two cars using one of the HPC chargers in Würenlos simultaneously, 190 kilowatts is still available per outlet. The tender that was announced mid-August to build the ‘German network’ of 1,000 fast charging parks by the end of 2023 stipulates a guaranteed minimum of 200 kilowatts per charging point, which should also be seen as a signal that things are moving in the direction of 300 kilowatts. When expanding the fast charging infrastructure, however, focusing solely on ever higher charging outputs would be too short-sighted. Firstly, because the vast majority of vehicles are not in this league. Secondly, because the availability of charging points is at least as critical, and thirdly, because it ignores the question of the efficiency of electric cars.

Only relevant for a handful of models

As mentioned, charging capacities in excess of 200 kilowatts have, to date, been the preserve of certain Tesla models and isolated premium segment vehicles – the Porsche Taycan, the Audi e-tron GT and the Mercedes EQS, for example. 2021 saw the launch of the first two mid-range vehicles – the Hyundai Ioniq 5 and its sister model the Kia EV6 – with 800-volt systems that can support charging in excess of 220 kilowatts. Aside from Tesla and the Hyundai-Kia group, no other manufacturers are harbouring similar ambitions in the mid-range segment, so it does not appear that 800-volt systems are set to become the new standard in the mass market in the foreseeable future. On the other hand, however, it is clear that cost, weight and resource issues mean that the range problem cannot simply be resolved with ever bigger batteries. Vehicle engineers, in fact, seem to be working towards shorter, more frequent charging stops rather than increasing battery size. So high charging power definitely plays a role when it comes to the everyday practicalities of electromobility. Here too, however, it’s important not to be dazzled by boasts of ever higher charging power.

Higher power does not necessarily mean faster charging

Even among fast charging champions in the 200 kilowatt plus range, it is not always the case that more output = shorter charging time. Firstly, peak power is rarely achieved in practice, because real-world conditions often differ from optimal conditions (a battery temperature of between 25 and 35 degrees and a low state of charge of around 10 percent). And secondly, the effective time it takes to charge has more to do with the average charging power across the entire charging period than with the maximum achievable value. If the stated peak values are only achieved briefly, the time advantage is negligible. Vehicle-specific charging curves show how long a vehicle charges at a certain level.

Ioniq 5 charges fastest despite lower maximum power

A comparison of different fast charging champions on the insideevs.de portal shows that Tesla’s Model S and Model 3 can reach the highest maximum values – around 250 kilowatts – but then when charging from 20 to 80 percent ‘only’ achieve an average value of 130 kilowatts (Model S) or 94 kilowatts (Model 3). In contrast, the higher average values of the Mercedes EQS (average 155 kilowatts) and the Hyundai Ioniq 5 (average 170 kilowatts) mean that, despite lower maximum power, they have a shorter overall charging time. In other words, if the charging power remains high across the entire charging period, the vehicle will spend less time at the charging station.

Question of efficiency ignored

Amidst all the talk of charging power and ever higher kilowatt figures, what is often forgotten is that the frequency of charging stops and therefore the total time that electric car drivers spend at charging stations also depends in no small part on the energy efficiency of the vehicle. So the equation should be: how many kilometres of range can I charge per minute? Over the same period of time and with the same average charging power, a vehicle with low consumption is able to charge more range than its higher-consumption rival. It would be good for the future development of electromobility, therefore, if manufacturers’ main focus was on the efficiency of their vehicles.