Electric cars are no longer the device of weirdos or the subject of passionate debates in anarchist circles – “battery-powered cars” are becoming a common part of the color of roads (including Czech ones). For now, they still remain in the “luxury upper ten thousand” segment, but they are rapidly spreading among the general population, for example in the form of company cars.
That’s why we continue to educate you and bring you closer to the specifics, advantages and pitfalls of the new drive, so that when it’s time for you to move to new technology, you know what you’re getting into. Many things are the same as in a regular car (steering wheel, pedals, etc.), but there are fundamental differences – first and foremost, charging. And we will focus more on him in our next miniseries. This introductory part is devoted to general information about the construction of batteries and the types of their charging, in the next part we will focus on how to treat them for the longest possible life and how it is with service.
The specific technical solution (and the number of components) varies from manufacturer to manufacturer, but the basic recipe is always the same: Electric car batteries consist of several (units to low tens) modules in which individual battery cells (about ten to twenty) are stored connected to one functional unit. Everything is connected by smart control electronics, usually supplemented by a cooling/heating system and housed in an extremely strong protective frame, which is a structural part of the floor of the electric car (to protect it in the event of a crash).
Today, the nominal (total) capacity of the modules most often ranges from 50 kWh to 100 kWh (smaller city cars also need smaller batteries, larger monsters, on the other hand, require larger batteries), but the usable capacity is slightly lower, because part of the capacity (kWh units) is dedicated as a protective buffer – so that it is not possible to discharge the battery to zero or charge it to 100%, which is not good for them for physical and chemical reasons.
You add energy to the batteries by charging from the electrical network, and there are two basic ways: slower (lower power, higher losses) and gentler charging with alternating current (AC) and faster (higher power) charging with direct current (DC).
Slower AC charging is mainly useful for charging at home/work where you are not pressed for time – charging takes several hours. Outputs range from 2.3 kW (ordinary domestic 230V socket) up to 22 kW (public chargers). The charging speed is not only affected by the power available at the connector, the limit is also the power of the on-board charger installed in the car (usually 7, 11 or 22 kW) – the batteries themselves work with direct current, to which the alternating current must be converted.
AC charging is therefore slower, but also more gentle – not only for the battery as such, but also for your wallet (even in public spaces it is one of the cheapest ways to charge, at home it is the cheapest and thanks to solar panels you can have it “for free”). At the same time, it is also more stable, which means that the charging speed (charging power) is less affected by the temperature (battery and surroundings) and the state of charge of the battery.
The power of fast charging ranges from 50 kW to 400 kW (depending on the specific charger), the limit is again the car’s ability to “hold” the given power (it depends on the electronic architecture of 400 V/800 V and other specifications) – you can also pour only a limited amount through the narrow neck of the container amount of liquid.
However, this does not mean that, for example, you can charge the Ioniq 6 with a battery capacity of 77 kWh with a maximum output of 239 kW in 20 minutes. The power of DC charging is variable during charging – the highest power approaching the maximum is when charging from a low capacity, but with increasing charge level it gradually decreases due to physical reasons (it slows down the most above the 80% level). That’s why the “effective charging” time (usually 10-80%) is most often given, because you never arrive at the charger with absolute zero, and above 80% it makes no sense to stay at the charger. For example, you can charge the mentioned Hyundai Ioniq 6 efficiently (10-80%) in just 18 minutes, charging to 100% would require additional (low) tens of minutes.
In addition to the state of charge, the temperature (battery and surroundings) also has a great influence on the charging speed, so in most cars it is possible to preheat or cool the battery before visiting the charger (usually automatically when you enter the charger as a destination in the navigation, or sometimes manually via a button or .choices in infotainment).
One card rules them all
The fragmented network makes life a little more complicated for electric motorists – there are several operators with their own contracts and their own price list. Today roaming is already possible (it also applies abroad), meaning that, for example, with a ČEZ card you can also use a PRE and E.ON charger (and many other operators even outside the Czech Republic), but charging prices outside the ČEZ network are much higher. A smart solution is to have a contract with several companies (ČEZ and PRE and you have covered most of the network in the Czech Republic).
But not everyone wants to deal with it and not everyone wants to compare prices in a complicated way (especially when traveling abroad). Each car manufacturer therefore offers its customers their own card (such as Charge myHyundai), which identifies them in a very wide network of contractual partners, they clearly know the charging price in advance and only have to pay one invoice at the end of the month. It’s not always the most convenient, but it’s definitely more transparent and, above all, more convenient.
DC charging is less friendly to batteries and is also more expensive – the latter is especially true in the case of HPC chargers (Hyper Charging), as racks offering power from 100 or 150 kW are referred to. Fast charging with high power therefore makes the most sense on the road, in order to conquer the next few hundred kilometers to reach your destination (Hyundai Ioniq 6 can charge 100 kilometers of range in just 5 minutes), where you can charge slowly and carefully with an AC charger or a weaker DC charger (50 or 75 kW).
In a week we will look at how to charge batteries for the longest possible life and how it is with their service.