- Unmanaged Charging dispatches full power to all vehicles, which can result in expensive utility bills or equipment overloads when too many are plugged in
- Equal Share Charging divides available power evenly among vehicles but not all drivers receive their desired level of charge before they depart
- First Come, First Served Charging prioritizes vehicles that arrive earliest with no regard for other drivers who arrived later but need to leave sooner
- Adaptive Charging intelligently manages charging based on driver needs and the building’s electrical load target — helping drivers get their desired energy in the time allotted while keeping utility costs down
Electric vehicles (EVs) play a key role in building a sustainable future for transportation. Yet despite their potential, there are still concerns among site owners regarding the transition to EVs, particularly the added expense of providing EV charging stations.
Modern EV charging methods can mitigate financial and logistical concerns, but not all solutions are created equal in terms of how well they meet driver demand. Here’s a breakdown of EV charging methods and how they differ.
When EV charging isn’t controlled with respect to driver demand or facility constraints, it’s considered “unmanaged.” In this scenario, drivers get however much power they need, but there are a few problems.
Take a look at the diagram below. The y-axis represents electrical load, and the x-axis represents time. The line denotes the electrical load target that has been set by the facility, that is, the maximum amount of power load the building operator is willing to accommodate.
When a driver plugs into a Level 2 commercial charging station, they receive full power regardless of how much they truly need and how long they intend to stay parked. As more and more EVs begin to charge, the load increases above the electrical load target. This could trigger peak demand fees (where a utility charges customers a more expensive rate for their highest 15 minutes of electricity use) or, in extreme cases, trip breakers and disable the entire charging system.
Site owners need to be cognizant of how many chargers the facility can support with its existing electrical infrastructure to avoid problems during times of high demand. This means either spending money on expensive infrastructure upgrades to bring more power to the site, limiting the number of chargers available for drivers, or both.
Not having enough chargers to go around is a big strike for any property, but it’s particularly problematic for workplaces — they risk productivity losses due to employees needing to stop what they’re doing to move their cars and jockey for available chargers. And for multi-family communities like apartment buildings or condominiums, residents are rapidly adopting electric cars and expect equitable access to charge their vehicles at home.
Equal Share Charging
A number of EV charging providers employ a managed charging method that divides available power equally among cars as they arrive. This method is called Equal Share Charging.
Check out the example below. The first car receives full power until the second car arrives, at which point each car receives half power. Adding a third car splits the power into thirds. And so on.
While this method avoids power overload and peak demand fees, there are significant drawbacks for EV drivers. Drivers receive energy with no regard for how much they need and by when. The result is unhappy drivers who can’t fill their batteries to their desired levels before they need to leave the property. This can present significant business challenges for the site owner. For example, drivers who have poor charging experiences may be less likely to return to a retail location to shop in the future.
Not only will the store lose business, but it will also miss out on revenue from charging driver fees: levying a nominal per-kilowatt-hour fee for charging is one of the ways businesses recoup system installation costs and shorten their payback period. If unsatisfied drivers shy away from using a business’ EV charging stations, this benefit goes untapped.
First Come, First Served Charging
Another common charging method, often referred to as First Come, First Served Charging, prioritizes vehicles that arrive sooner over ones that arrive later. As each vehicle plugs in, it is allocated its maximum charging rate until the site has reached its electrical load target. Vehicles arriving after the limit is reached must wait until earlier arrivals finish charging.
In the example below, the first two vehicles to arrive receive their maximum charging rate. The third vehicle to arrive must wait until one of the other vehicles finishes charging — but since it must depart sooner, it leaves without receiving any charge at all. The fourth vehicle to arrive is allowed to charge once the first vehicle finishes but doesn’t receive its desired energy before it too must leave.
This charging method raises an important question: Shouldn’t drivers who need to get back on the road sooner get charged up first? If not, people with less flexible schedules are put at a big disadvantage. Imagine this was the case in a multi-family apartment building. Current tenants who own EVs might reconsider renewing their leases, and prospective tenants may be wary of renting the property at all.
In Adaptive Charging, power distribution intelligently changes based on driver inputs such as how much energy they want to receive during their charging session and how long they anticipate staying plugged in (their “dwell time”).
Cars that need power sooner are charged quicker than cars that need the same or less energy over a longer period of time. You can see this concept in action in the diagram below: the vehicles with shorter dwell times (Cars 2 and 3) receive power at a faster rate compared to the vehicles with longer dwell times (Cars 1 and 4.)
Managing charging adaptively helps drivers get the maximum power they want before they must leave. Power draw is also flattened, keeping levels within the facility’s electrical load limit and eliminating spikes that could result in peak demand fees from the utility.
Adaptive Charging is particularly ideal for site owners who are looking to install a large number of EV chargers, as is often the case with workplaces, shopping centers, and other properties that host many vehicles at a time. The key differentiator of Adaptive Charging is that charging is optimized around the driver rather than just fitting the driver into the capacity of the site. And since the method makes more efficient use of available power, sites are able to install a larger number of chargers without the need for major infrastructure upgrades.
Choosing an EV Charging Method That’s Right for You
Like with most other business decisions, your ideal EV charging method depends on your specific needs and goals:
- Maximizing driver experience: Who are you providing EV charging for? What types of vehicles will need to be charged and how long do they normally stay on site
- Minimizing power loads: What's the maximum electrical load you wish to accommodate?
- Avoiding expensive upgrades: Do you have funds for expensive infrastructure upgrades or do you want to maximize the power you already have on site?
- Planning for today and the future: How many parking spaces on your property do you plan on equipping with EV charging stations?
- Complying with regulations: If you live in an area with EV-friendly building codes, how many are you required to designate for EVs?
A qualified EV charging developer can help you determine the answers to these questions and ultimately recommend a solution that will not only meet your needs as a site owner or operations manager, but also the needs of the drivers who park on your property.
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