Faster EV Charging, Further Ranges

By Contributed Article | December 10, 2024

Electric vehicle technology is rapidly improving, along with fast EV charging infrastructure and connectivity systems that make it faster and easier to charge at home and on the road.

Stricter air pollution regulations in a growing number of cities are prompting restrictions on diesel vehicles and putting pressure on the automotive industry to design electric vehicles that offer fast EV charging. At the moment, however, charging time and range are still major factors in winning over consumers; despite the claims and promises of manufacturers, physics still comes into play. Here are a few simple facts that cannot be overlooked.

First, calculate the charging time. To do this, take the battery capacity of a vehicle in kWh and divide it by the power (kW) of the charging station. The result is the number of hours required for a full charge (0 to 100%).

Next look at the elements that make up the EV battery charging process: the mains (grid or power source), the charging station, the charging cable, and the charger itself. As with any chain, the weakest link determines the maximum charging power. A charger designed for 6.6 kW won’t be able to charge at a 22 kW charging station. Know under which conditions the advertised loading times are possible, i.e., at an external three-phase high performance charging station or at home?

Every element in a charging system contributes to performance. SCHURTER’s new CSO Heavy Duty Fuse Clip is ideal for charging systems as well as photovoltaics, inverters, and other power applications.

Charging at home

One of the best-selling electric vehicles, the Tesla Model 3, has a 100 kWh battery. Charging at home is slow but easy for drivers to do overnight by routinely plugging in when parked. The battery needs eight hours at a standard Level 2 wall charger to achieve a complete charge and a range of 272 miles. However, a Tesla Supercharger can accomplish the same in less than an hour at phase 3 with DC fast charging, and in under 30 minutes when the charge limit is set to 80%.

Fast circuits always carry the risk of excessive emissions of electromagnetic interference signals, which must be reduced. This problem can be overcome with EMC filters with high attenuation and a clever circuit board layout – in the 1-phase range usually even with discrete components. SCHURTER’s new FMAC NEO
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Required charging capacity

How many charging stations are the reserves of the house connected load sufficient for, and will it be possible to boost them later? While owners of detached homes can easily get a powerful home EV charging station, the same is not true for apartment owners and tenants who park their vehicles in a shared car park. The apartment owners must give consent and tenants need the permission of the landlord. Furthermore, the power system for underground car parks are typically not designed for loads needed to accommodate multiple vehicles. If several electric cars are attached at the same time, it is best to choose intelligent EV charging stations which measure the load on the power grid and include it in the respective charging capacity.

Fast charging is “no good”

At the moment at least, fast charging harms a lithium-ion battery. The IU charging process, which is used for lithium-ion cells, works with constant current (CC) and constant voltage (CV). EV charging time depends on various factors, above all temperature with higher charging capacities. Short charging times or high charging currents have a negative effect on the electrode material, shortening the service life and the number of cycles. Gentle charge/discharge massively increases the service life. Battery technology is evolving rapidly, however, and new lithium-ion sulfur (Li-S) batteries and other emerging battery technologies will make fast charging much more efficient and less impactful.

Lithium Plating

Charging and discharging Li-ion cells at high currents or low temperatures can lead to lithium plating. Lithium ions are preferably deposited on the anode surface instead of between the layers of graphite. This effect leads to significant losses in performance, lifetime, and safety. In extreme cases, lithium plating can even lead to a short circuit or, since metallic lithium is highly flammable, to a fire.

Communication / BMS

Battery management systems (BMS) are responsible for controlling and monitoring the charging and discharging process of high-performance battery packs. Their main task is to ensure that each individual cell does not exceed or fall short of a defined state of charge (SoC) during both EV charging and discharging. The SoC value denotes the remaining capacity of a battery in relation to the nominal value. The value is given as a percentage of the fully charged state. A 30% value means that the battery still has a residual charge of 30% relative to full charge. Depending on the application, the upper and lower limit values for the SoC are 20% to 100% for max power and 30% to 70% for max service life.

Currently, the various EV charging interfaces and standards can be confusing for potential consumers, although standardization will soon improve charging experience. New, optimized interconnects will help improve the charging infrastructure. One area that still needs to be simplified, particularly in the case of public charging points, is access authorization and payment options. In time, paying to charge a vehicle will be as fast and simple as paying for gas.

To learn more, visit SCHURTER or find the full white paper here.