Editor’s Note: This article originally appeared in the digital edition, “EMS1’s Guide to Ambulance Electrification.” Learn more and download your copy here.

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By David Wright, DHPE, PA-C, NRP, FAEMS; and Kate Randolph, BS, PA-S

Electric vehicles (EVs) are not coming; they are here. In 2022, worldwide EV sales totaled approximately 7.8 million, a 68% increase from the previous year, and accounted for approximately 10% of automotive sales. Commercial adoption of electric vehicles has begun, with vehicles such as the Ford Transit EV. Amazon and Rivian created a partnership to roll out electric vehicles for package delivery in over 100 cities in 2022, with plans to have them in over 100,000 cities by the end of the decade.

| RESOURCE: Download your copy — EMS1 guide to ambulance electrification

To understand the degree of electrification, lets first dive into the various types of electric vehicles.

• Battery electric vehicles (BEVs). These vehicles run exclusively on battery power. They are charged using various charging stations, many of which are commercially available for fast charging. These vehicles have typical ranges of 150-400 miles per charge.
• Plug-in hybrid electric vehicles (PHEVs). These vehicles can run exclusively on battery power, exclusively on gasoline, or utilize a hybrid style drivetrain. They have a much smaller battery, typically only supporting 20-40 miles of range, with a gas-powered engine that will supplement range when the battery power is depleted or additional range is needed. The battery needs to be plugged in to a charging station to replenish the charge as needed.
• Hybrid Electric Vehicles (HEVs). Hybrid vehicles are the easiest way to electrify a fleet. These vehicles are powered by internal combustion engines in combination with one or more electric motors that utilize battery store energy. The biggest difference is that these batteries are charged by regenerative braking and the internal combustion engine, and not by plugging in the vehicle.

These electrified vehicles obviously contrast to traditional vehicles that are 100% powered by internal combustion engines (ICE) that rely on gasoline or diesel fuel to power them.

For the purpose of this article, we will primarily discuss the use of BEVs that are powered on 100% electricity.

How charging works

To understand the charging downtime, we must first define the various speeds at which electric vehicles can charge.

Charging time is often discussed in kWs and is based on the amount of energy able to be transferred from the charging station to the vehicle in a given time. This can range from 1 kW per hour (kWh) to 350 kWh.

Back to basics science class

Tounderstand the charging process, we must first go back to our high school science class and recall that wattage is determined by amps and voltage. This is demonstrated by the equation P(W) = I(A) × V(V). The P (power) in W (watts) is equal to the I (current) in A (amps), times the V (voltage) in V (volts). Electric safety states that current draw should not exceed 80% of the rated circuit for continuous power draws (as electric vehicle chargers do).

Most level 1 chargers are basic household current (110 V) and most circuits are rated for 15 A.

At 80% this translates to approximately 12 A at 110 V. This leads to approximately 1,320 W (12 x 110) per hour or 1.32 kWh.

A level 2 charger will typically be on 240 V, can be hardwired to a 60-amp circuit and will have a constant draw of 48 amp. This leads to a 11,520 W output or 11.5 kWh.

Level 3 chargers are direct current fast chargers (DCFC) and can provide charging speeds of 60-350 kWh.

Obviously charging times are going to vary based on the efficiency of the vehicle and the size of the battery. To highlight this, we will compare the Ford F150 lightning pickup truck, the Ford Mustang Mach-E SUV, the Rivian R1T and the Tesla Model Y SUV.

EV charging breakdown

It is likely that most vehicles will be charged using a level 2 charging system. It is assumed this will be the case as a 240V line is fairly simple and cost-efficient to install.

Installing a DCFC Level 3 charger can cost up to $200,000, where a 240V line is simple for any electrician to install, and chargers can cost about $500 dollars. The time saved from Level 1 to level 2 is commonly looked at as effective and most electric vehicle owners use level 2 charging at home.

It is important to remember that just like our ICE counterparts that do not use a full tank of gasoline every shift, it is unlikely for an EV to use the whole battery at any given time.

Having the ability to charge during downtime (i.e., back in quarters, at the hospital) will increase range, and likely decrease administrative anxiety and time out of service for fueling.

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ABOUT THE AUTHORS

Kate Randolph, PA-S, graduated with honors from Central Methodist University with a Bachelor of Science Degree in Biology. She currently holds multiple certifications and is active in EMS research. She currently attends Stephens College PA program in Columbia, Missouri. She has great interest in emergency medicine, pediatrics and neurology. She is also an active member of NAEMSP, advocating for the PA profession in EMS.

This article, originally published in April 2024, has been updated.