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Charging Electric Cars
This is an attempt to summarize the charging infrastructure a bit. Anyone who buys an electric car needs various cables for charging. Some are included, while others you have to purchase separately. There's
probably
always an (emergency power) cable included, the one with a household plug (with a grounding pin) on one end. Integrated into this cable is a charging brick named after its shape.
This is an electronic device that controls the charging process via a data line and provides additional safety. Electricity transmitted in this way is alternating current. When charging at home, there is simply no
other way to do
it, unless one were to purchase a very expensive AC/DC converter. With public charging, both options are available, depending on the charging station.
Schuko outlets can be fused at 10 A. In that case, you can only supply 10 A * 230 V = 2.3 kW. When transmitting electricity, electrical power in kW is always important. When assessing the charge level of a
battery, the capacity in kWh is the key factor. So if 50 kWh are transmitted, then, theoretically, a backup power cable would require 50 kWh ÷ 2.3 kW = 21.7 hours.
In somewhat more modern electrical systems, and, of course, in new buildings, the individual circuits are protected by 16-amp fuses. So you could charge at 16 A × 230 V = 3.68 kW. That would take 50 kWh
÷ 3.68 kW =
13.6 hours and could even be done using an emergency power cable. Experts point out that the Schuko connection may not be rated for such a high continuous power load and could overheat.
There are connectors designed for this problem that are used when camping. So you'd have to replace the plug and the outlet. Of course, a cable end with both types of plugs would be even better,
but you'd have to buy that separately, because the unused part would naturally have to be automatically disconnected. However, you shouldn't spend too much on a cable like this, because it's the
least convenient charging option.
Electricity is generally supplied in three phases, at least in Germany. For this reason, it is sometimes referred to as high-voltage current (400 V). Instead of three wires labeled L, N, and PE, there are five: L1,
L2, L3, N, and PE. For the charging process, the only important factor is that 230 V can be drawn from each of L1, L2, and L3 together with N, meaning that, in the best-case scenario, the charging power
triples.
But the AC/DC converter in the vehicle has to be capable of doing that, too. If the vehicle, such as a Tesla, comes from a country where three-phase alternating current (three-phase power) is not common, it
often does not have a corresponding AC/DC converter. However, there is sometimes a small consolation: namely, that this converter can handle considerably more than 16 A on this single phase.
In these vehicles, Tesla, for example, only one of the two data lines in a five-pin connector is needed, of course: three for AC and two for DC. So in the U.S., a Tesla gets by with just a single round plug
connection. When a car like this is shipped to Europe, the round plug is reserved for alternating current, and the elongated plug with two poles below it is reserved for direct current.
However, that only refers to plug compatibility, so it by no means means that it can also charge using three-phase power. To avoid having to install a completely different and more expensive charger,
Tesla makes do with a modified 'charging brick'. You tap into all three phases and send a higher current to the car through one of the available phases.
So how does electricity get into the car through three different paths at the same time? To do this, you must have a red outlet for so-called high-voltage current instead of a Schuko or blue camping outlet. It is
either already installed in the garage, can be installed, or is the end of an extension cord connected to such an outlet in the basement, for example, next to the meter box. Then a suitable charging cable and
charging brick are attached.
So a charging brick like this is more than enough for charging at home. If all the safety electronics could be integrated into the meter cabinet, some electronics in the plug would likely make even the cabinet
superfluous, and the charging cables would be significantly cheaper. It gets more expensive with a wallbox, which has to be installed close to the car and the purchase cost is usually double.
No, higher charging power via a wallbox generally isn't practical for households, because anything exceeding 3 * 16A requires approval from the utility company, and even then, in Germany, they only allow a
negligible increase. After all, charging at 11 kW is more than enough, since there isn't a single electric car on the market that couldn't be fully charged overnight at that rate. Only at businesses and public
charging stations is it possible to charge at up to 3 * 22A, that is, twice the charging power.
It should be noted, however, that the potential charging power depends on the charging station, the car itself, and any intermediate electronic components. Wallboxes and charging bricks allow you to
configure or schedule these settings. The latter would make it possible to take advantage of lower electricity rates. Charging is reduced to preserve the battery, which is only possible by charging more slowly
and by avoiding levels above 80 or 90 percent and below 20 or 10 percent.
These days, fast charging is considered almost more important than a huge battery. Of course, this does not refer to drawing alternating current from the grid. There is a need for charging stations that
convert this to direct current and, presumably, store it in large quantities in the future so that the grid does not collapse when many electric cars are charging quickly at the same time. There are already some
vehicles that charge with up to 800 V DC instead of 400 V.
Tesla has a clear advantage here because it has a large charging network that was originally built exclusively for its vehicles and is constantly being updated to support the latest charging speeds in the 400-
class. Another very important point is how the charging process is organized. With the others, it's often impossible to manage without the right card and a cell phone. With Tesla, you just plug it in and
everything runs automatically including billing. However, two cars should not be parked at adjacent charging stations, as this can significantly reduce the charging speed.
The charging curve, for that matter. This is deliberately ignored in advertisements for electric cars. This assumes a consistently high value for the entire charging period, which is never the case in practice. Even
with a Tesla, the range at 80 percent can sometimes be less than half what it was at the start. The high-voltage battery can be a beast and may limit the charging power from time to time.
That's largely due to the battery's temperature; it really shouldn't be too cold or too hot. The former can affect acceleration, while the latter can affect charging. It is becoming increasingly important that
such an electric car has a liquid cooling system that allows it to regulate its own temperature. If that is not available, the only option is to drastically reduce the charging power, in some cases, to just below the
peak power during AC charging.
In the meantime, however, peak charging power has reached levels where, in addition to using cables with massive cross-sections, it must also be cooled by liquid. For that reason alone the potential future
widespread switch to 800 V will make things much easier here. People also often forget about the losses that occur during fast DC charging at the charging station, in the cable, and in the car itself.
It's very easy to reach 10 percent or more. Once again, Tesla takes the cake here, because it keeps the batteries within the proper temperature range even when the car is parked. That doesn't stop
until the remaining range reaches 20 percent. If the car is permanently plugged in, as recommended by Tesla, the manufacturer clearly considers battery life to be more important than power consumption. For
example, a VW ID.3 has virtually negligible power consumption when stationary.
Charging capabilities in the DC sector are currently undergoing a transformation. There's talk of 'up to 350 kW', but so far we've only seen 250 kW or a little more. And even those rarely lasted very long. For
example, Porsche is partnering with the operator Ionity, but they've just raised their prices drastically. Stores and furniture retailers are still advertising 'free shopping', though this probably won't last forever.
So unless the cost of fuel for internal combustion engines rises significantly as a result of the climate crisis and political crises, the future price per kilometer for electric cars and diesel vehicles could be
roughly the same or even lower. Despite assurances to the contrary from some enthusiasts and government incentives, the total cost of purchasing and maintaining an electric car is by no means that much
cheaper than that of a comparable internal-combustion vehicle.
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