Recently, electric vehicles (EV) have become more reliable (quality) and marketable (driving range, higher number of available models) products. EVs play an important element for decreasing CO2 emissions and increasing energy efficiency. Installing charging infrastructure is one crucial element in order to increase the attractiveness of EVs to overcome today’s challenges of sustainable drivetrains and fuels.

Charging Demand for Fleets

Many companies have started converting their conventional fleets to electric ones. Companies like FedEx, IKEA and some police stations are in a transition phase exchanging combustion vehicles to EVs. Some large fleet operators may need their own charging infrastructure. The charging infrastructure requires different features whether the vehicles are recharged when parked (mainly overnight) or during working hours (on the run).

1. Charging while parking: Mainly AC charging terminals (slow charging) are used. The Infrastructure may be built in depots or private parking garages or at home and not available to the public.
2. Charging on the run: Mainly DC charging terminals (fast charging) are used. This type of charging is required for trips which are longer that the driving range of the battery capacity.

Table 1 - Charging Infrastructure

Source: Table based on Borges, J., Ioakimidis, C. S., & Ferrão, P. (2010)

Table 1 shows the difference of costs and charging time between different charging infrastructure types. In order to charge the vehicle to its maximum capacity at depot costs €1.75 in less than 7 hours, however in fast charging station it costs €4.66 in 30 minutes.

There are different charging methods in order to charge electric vehicles: Conductive charging, inductive charging or battery replacement. The inductive charging technology produces an electromagnetic field which is used to transfer energy between two objects. This is usually done with a charging station. Energy is sent through inductive coupling to an electrical device, which uses that energy to charge batteries or run the device. However, there is many disadvantages related to this method: charging takes a long time, the efficiency is very low and the costs are very high.

Conductive charging system use direct contact between the EV connector and plug. The cable can be fed from a standard electrical outlet or a charging station. There are two main varieties in charging technology, the first one consist of hey operate using alternating current (AC), then a convertor used to convert alternative current (AC) to direct current (DC) which is the one enter to the battery. In Level 1 the electricity drawn directly from the local distribution system, however in Level 2 charging can also be provided at workplace locations, hotels, gas stations, private parking lots, and public locations.

The second variety is Level 3 and above, which uses DC charging directly to the battery without the need for convertor, therefore deliver much more power. Electricity is provided from either private or public locations. This system is also known as Direct Current Fast Charger (DCFC). The power available for DC Charging (Level 3 and above) can vary from power levels similar to AC Level 1 and 2 to very high power levels as shown in table 2. Note that the reference battery size is 75 kWh.

Table 2 - Variants and charging characteristics of EV chargers, assuming power usage of 0.37 kWh per mile

Source: Table based on Lee and Clark, 2018

As it shown in the table, level 4 needs 15 minutes in order to half-fill a 75 kWh battery size and it would need only 30 minutes to recharge the battery to it is maximum capacity. While Level 5 takes six minutes to fill 37 KWh battery size, which means it would take only twelve minutes or more to fully recharge from empty.

Three basic charging strategies exist:

1. Overnight charging and performing the entire journey during the day without recharging;
2. Overnight charging and performing the journey during the day, with the battery capacity being insufficient to complete the entire journey, so that a charging station along the route has to be used to recharge;
3. Charging overnight and recharge during stops at customer’s premises, and getting through the day in that way.

Commercial fleets in cities have mostly a fixed daily routine and the tours for the EVs are seldom longer than 80 to 100 km according to the capacity of the batteries. By this trip length the EVs are charged in their depots overnight. By extended tours an external charging point will be used and the estimated charging time is integrated in the time table for the driver. In cases where EVs and fleets are run 24/7 fast charging is not the best solution: it shortens the life time of Li-Ion-batteries. In those cases battery swapping is able to keep a 24/7 service running. In theory, the higher costs of battery swapping will be compensated by an intense and longer usage of the EV respective the battery.

Basically, there are four possible locations where vehicles can be charged: the charging infrastructure available at companies, in the public space (including public charging infrastructure around building sites), at the destination on the customer’s premises and at the homes of the employees. Generally, the greatest demand for electricity for charging occurs at business locations and depots – usually on industrial sites during night when vehicles are parked and charged. The cheapest way of charging is by using your own charging points at the site of a business that is a bulk consumer of electricity and has a low rate. The highest-capacity charging stations (350 kW) are only required for a small proportion of all businesses. A lower-capacity charging station is usually sufficient for vehicles and less heavily laden journeys.

Rough breakdown of vehicles by charging station type

• Delivery vans: these mainly use charging solutions of up to 50 kW. In due course with larger battery capacities they could possibly also use 150 and 350 kW in the wake of the passenger vehicle market.
• Trucks and buses up to a Gross Vehicle Weight of 10 tons: these will also mainly use solutions of up to 50 kW. Due to the bigger required battery packs, they will probably switch to 150 and 350 kW solutions sooner.
• Heavier goods transport (from a GVW of 10 tons) will mainly use faster charging solutions (starting at 150 kW).

Table 3 shows estimated TCO of the various types of charging stations.

Table 3 - Overview of the TCO and cost price per kWh for a given annual consumption

Source: Table based on van den Hoed, Halm & Kin (2019)