The New Math of Electric Vehicle Charging

(DGIwire) – Electric vehicles (EVs) are the future—but they won’t truly go mainstream until they can be recharged as quickly as gasoline-powered vehicles can be filled up. That’s a challenge in places like the UK, where the government has announced a total ban on gas and diesel vehicles by 2040, according to The New York Times. Car drivers are used to spending five minutes filling a tank with enough gas to go 300 miles. How can EVs provide the same experience? Or ensure that recharging an electric van or truck takes no more than 15 minutes to an hour, about the length of a reasonable driver break?

One major roadblock concerns the lithium-ion batteries that power most EVs. Not only can they catch fire if they charge or discharge too quickly; a brief look at the math of lithium-ion charging illustrates another big problem. To drive an electric car 300 miles takes about 100 kilowatt-hours (kWh) of usable energy—the same amount used by a little over three U.S. households daily, according to the U.S. Energy Information Administration. Electric delivery vans and 18-wheelers would each take respectively more energy to charge up for that same distance drive.

If a standard residential wall socket delivers 3kW of energy per hour, a standard electric car battery (100kWh) would take about 33 hours to charge fully. Yet a van would still take a week, and a truck a whole month, to fully charge, at that rate. Although street chargers available today can deliver faster charging (30kW), these still require four hours to charge an electric car. Even with Tesla’s 120kW chargers, it takes about an hour to charge an electric car—while the most cutting-edge chargers today, announced by Electrify America in the U.S. and Ionity in Europe, deliver 350kW.

“Lithium-ion batteries today can’t handle a 350kW charge rate, and even if they could, it still leaves people far from the goal of a five-minute recharge for a car,” says Stephen Voller, CEO of ZapGo Ltd, the developer of Carbon-Ion™ (C-Ion®) cells, a fast-charging and safe alternative to lithium-ion batteries. “What is needed for that is a recharge rate of 1 megawatt (MW), which can be made possible with innovative materials such as Carbon-Ion.”

In Voller’s view, a promising application for ZapGo’s Carbon-Ion cell is for it to be used effectively like a battery charger. Indeed, one of ZapGo’s initiatives involves ensuring a very high rate of DC charging of battery electric vehicles, where the electric grid can be buffered.

According to Voller, the way this works is that filling stations want to offer very high-speed charging. To avoid digging up streets, the grid can be buffered by putting Carbon-Ion storage into the filling station site that is filled at standard electricity rates, such as at night when there are off-peak rates in effect. When vehicles turn up for charging, they can charge very quickly because ZapGo’s cells discharge rapidly.

“The challenge of converting the world to EVs will require new thinking and a new way of looking at not only charging EVs but also how the energy will be supplied,” adds Voller.