As electric vehicles grow in popularity, issues surrounding charging are a stumbling block for consistent uptake.
Limited availability of chargers and slow charging speeds caused 1 in 5 EV drivers in California to switch back to gasoline vehicles in 2021. These are also pain points for fleet operators — which have larger vehicles with larger batteries such as buses, trucks and delivery vans, and time constraints on charging opportunities.
It’s no surprise that the advent of ultrarapid charging — which can fully charge a commercial EV the fastest, with power levels far exceeding 150 kilowatts — has been welcomed by fleet operators and governments. This solution, however, may be a problem in disguise. Major drawbacks include increased costs and emissions, faster battery degradation and additional pressures on an already overworked electric grid.
For fleet operators, ultrarapid charging may finally offer the solution they have been looking for — the superfast charging of batteries back to full power without disrupting operations for long periods of time.
The truth is ultrarapid charging is a double-edged sword. To make the most out of it, fleet operators might be tempted to add more batteries or larger-sized batteries to their fleet. Increased battery capacity means more energy, longer journeys and fewer charging stops, but it comes with increased emissions and capital expenditures.
If fleet operators aren’t encouraged to upgrade their batteries, they may be forced to instead. To receive such high volumes of power, batteries must have higher capacity, otherwise they are at risk of being damaged. To keep batteries protected, the charging power should be around one-third of the battery capacity size. To achieve this ratio, an electric bus would need a total battery capacity of 1,300 kilowatt-hours for healthy charging from a 400-kW ultrarapid system (most electric buses have batteries closer to 300 to 400 kWh).
Choosing ultrarapid charging to support operations results in additional battery costs because there is a need for larger or additional batteries. From an environmental perspective, this adds weight, which subsequently creates more carbon dioxide emissions, as heavier vehicles emit more emissions than smaller ones. From an infrastructure perspective, single ultrarapid systems can start at $100,000 for one charger.
A battery is at its healthiest when its state of charge remains between 20 and 80 percent. Despite this, the majority of commercial EVs are fully charged (i.e., when batteries have less than 15 percent charge) back to 100 percent overnight or end of day to reduce interruptions to service. Not only does this empty-to-full charging reduce the battery’s lifespan, doing so at ultrarapid speeds can accelerate the rate of battery degradation.
Charging a battery at its minimum and maximum thresholds produces greater heat inside the battery. Internal heating, in general, is detrimental to a battery — and the higher currents from ultrarapid charging can cause more heating and stress in the battery plates. Under heat and stress, the electrodes, which give the battery its function, start to disintegrate, causing the battery to become less efficient and reducing its lifespan over time.
Consequently, depending on the level of ultrarapid charging and type of battery, research shows a loss of at least 10 percent of battery lifespan and up to 23 percent in some cases. Commercial EV owners using ultrarapid charging should therefore expect to replace their batteries more frequently — increasing both their costs in terms of battery purchase and the service interruptions they experience during battery replacement.
Ultrarapid charging can repower batteries with short downtime during operational hours, in addition to supporting typical charging behaviors to fully power empty batteries quickly overnight or end of day. Regardless of the scenario, ultrarapid charging requires expensive grid upgrades. The grid must cope with high levels of energy demand for large fleets to charge their batteries — and in overnight or end-of-day cases, all at once.
The underlying problem with ultrarapid charging is that it doesn’t optimize charging — it simply reinforces existing ineffective charging behaviors. Such technology may solve some challenges, but it simultaneously creates new problems for fleet operators, who must be prepared to pay for these costly mistakes.
Instead of ultrarapid charging, offering regular fast-charging power between 25 kW and 150 kW delivered wirelessly may be a better solution for EV fleets.
Commercial EVs can charge along their operational routes as they drive using high-powered, but not ultrarapid, charging facilities.
Wireless charging also permits fleet owners to charge multiple EVs simultaneously. Typically, a stretch of wireless electric road can charge three or four vehicles driving over it via dynamic charging, or dozens of commercial EVs that are parked via static charging from a single unit. This results in significantly less hardware costs required to charge a commercial fleet.
By introducing shorter, lower-powered, distributed charging sessions, fleet operators would also not need to rely on overnight charging to reenergize their fleet. This would drastically reduce large grid connections at fleet depots and help prevent overloading the grid.
Is it really sustainable to imagine a world where EVs rely solely on ultrarapid charging? If so, the future of charging is filled with larger batteries with more emissions that need frequent replacement. This also means a distressed future for the electric grid, which would be strained providing excessive power to fleets.
The inefficient charging practices that ultrarapid charging would create are paradoxical to the more sustainable economy the EV industry is working toward.
While ultrarapid charging may have an important role to play in reducing range anxiety and supporting consumer EV adoption, for fleet operators, the answer could lie in a more practical, lower-powered and sustainable solution, which is kinder to the planet, safer for the grid and more feasible on their budgets.