Electric Vehicle Charging Stations
for Travel Plazas

BMW, Audi, Porsche, GM, Ford, VW and nearly all other vehicle manufacturers are bringing the future closer with the conversion from conventional to electric drivetrain vehicles. The auto industry is investing hundreds of billions into manufacturing plant transitions, battery technologies, and new supply chains. Tesla Models S/3/X/Y, Jaguar I-pace, Audi E-tron, BMW i3, Chevy Bolt, Hyundai Ionqi, Mini Cooper SE, Nissan Leaf, Porsche Tycan, and many other models are already available this year. The list triples, then quadruples with hundreds of new models from nearly all auto manufacturers in subsequent years. 2019 global auto sales topped at 75m units. Of those sales, 1.65m or 2.2% were pure-electric EV’s. This percentage is estimated to increase from 15% to 25% with 20m in EV sales in the year 2025.

What typically determines the type of charger needed is based on the amount of time the EV driver will be staying at the location. For travel plaza patrons, that time is approximately 15 - 25 minutes. Before the charger type is determined, an explanation of available types is warranted.

There are many types of charging stations. Chargers are categorized as either Level 1, 2, or 3 and are advertised by their power output in kilowatts (kWs). Level 1 chargers are very slow at 1.1kW - 2.4kW output and are designed for home and portable charging. This class of charger is mostly for plug-in hybrid vehicles (PHEVs).

Level 2 chargers are faster at 3.3kW - 19.2kW output and are designed for pure electric vehicles (BEVs) and are mostly found in extended-stay locations such as hotels or the workplace.

Level 3 chargers are much faster at 50kW - 350kW output and are designed for fast charging pure electric vehicles. These chargers are found at quick stop locations such as highway rest stops, travel plazas, and parking garages. Level 1 and 2 chargers use AC (Alternating Current) power sources while Level 3 uses a DC (Direct Current) power source.

The amount of power output coupled with charging session time indicates how many miles are added to the range of the electric vehicle (for example: 9.6kW x 60min = 30mi of range). Ultimately, this is the information needed to determine the type of charger to install at a given location. The chart below displays approximately how many miles per hour are added to the vehicle’s range based on the charger’s power output.

EV drivers typically do not let the range of the battery dip below 20% - 25% before recharging. This means the vehicle will have between 35 - 80 miles left of range prior to charging. The typical range of an EV is 200mi - 350mi, so it is reasonable to surmise that the driver will want to add about 110mi - 250mi of range before proceeding. As mentioned, travel plaza patrons stay an average of 15 - 25 minutes. This indicates that an available high-powered DC fast charger (DCFC) will be needed to keep them on their way without delays.

Based on the above information, you can determine with more granularity what specific type of charger is needed to satisfy the patron in the chart below. Note that the optimal charging range for travel plaza patrons is indicated in blue.

Based on the information in the above chart, it’s clear that a 150-350kW DCFC is needed to satisfy a travel plaza EV driver patron.

As with determining the number of traditional fuel stations needed for a travel plaza, determining the number of EV charging stations needed depends on the traffic volume for a given area and time of day. For EVs, this is not as simple to derive given the potential lack of EV volume data for a specific region and the fact that the EV market is a moving target, growing at a feverish pace. Many times, traffic information can be obtained from local or state government departments such as the Department of Transportation but most reports still do not break out EV data. A way to estimate the EV breakout is to simply figure in its percentage of the total volume. Several media outlets and government websites gather this information conveniently by state.

Another consideration is that the calculation/ratio to determine conventional vehicle visits won’t be the same as EVs because, as previously mentioned, the EV driver can charge their vehicles at home or the workplace. This means the ratio of EV driver patrons needing a charge will be lower than conventional driver patrons given the same traffic volume conditions. An estimate of that ratio adjustment may be 80% of the conventional ratio. For example, if there are 50 conventional vehicle visits to the plaza out of a volume of 1,000 passers-by, there would be 40 EV visits if all 1,000 passing vehicles are electric.

As mentioned, another factor in estimating the number of chargers needed is the growth of the EV market. The travel plaza property owner should prepare the infrastructure for that growth. A property owner may decide to prepare the site with fewer units to start, but design the electrical infrastructure to support several units down the road. For example, only a single DCFC may be needed in 2020, but in 2022, 5 charging stations may be needed. In 2025, 10 stations may be required. It is important to size the transformer and other electrical equipment to accommodate future additions. Technology and pricing will improve over time, so it makes more sense to start with fewer units for that reason as well.

There are several elements that can contribute to the cost of installing DCFCs. Those costs include, but are not limited to:

There are also several elements that can reduce the overall price of DCFC installations including incentive programs from municipal, state, or federal government. In addition, the electric utility company may provide substantial discounts if they consider the site to be a revenue stream for them. Electrical infrastructure costs for DCFCs can vary greatly depending on the above. DCFC equipment costs can range from $25,000 - $110,000 per dispenser depending on the kW output and configuration needed. Infrastructure installation can almost double those costs. In general, you can expect to pay about $1,000/kW of output per complete installation without any incentives to reduce the cost. The cost per kW ($1,000/kW) is likely to be reduced further the higher the output of the charger (ie: 200kW-350kW).

All DCFCs come with a management platform, typically cloud-based, that provides configuration, management and status features for the chargers. One of the benefits of the platform is the ability for the property owner to apply any number of pricing policies. For example, chargers can be set up to bill EV drivers by kWhs added, per time of use (per min or per hr), fixed per charging session, and other methods. These methods can be changed any time if desired. Chargers can also be set up to charge different fees for different times of the day when usage demand is greater, or weekend vs. weekday. Idle fees can also be defined whereby if the driver leaves the vehicle connected beyond the charging session time, they will be billed extra fees.

There really is currently no standard pricing model, however, EV drivers do expect to pay more to charge their vehicle quickly. When charging at home, EV drivers are used to paying their standard electric utility rate at a national average of $0.12 per kWh. At Tesla SuperChargers, the average rate is between $0.24 - $0.30 per kWh added for DC fast charging. Other networks have been known to charge by the minute for fast charging at rates up to $1 per minute during peak hours. In some cases, DCFC rates have been seen charging by the session at, for example, a $15 flat fee.

How to determine a return on investment will largely be dependent on rate of use, and the pricing rate applied to the EV driver minus the electric utility fees (commercial rates are typically about $0.07 per kWh). Another critical value to understand is how many miles of range are added for every kWh added to the battery during a charge. This value is highly dependent on the efficiency of the vehicle battery itself, however, it is safe to estimate that for every kWh added, 3 miles of range are added.

Given the above knowledge, a conservative example for ROI for one 150 kW DCFC is the following: