Electric Car HyperCharging Is Hyperbole, For Now

By · June 19, 2013

Silex Chreos

The Silex Chreos, the as-yet-unmade luxury sedan Silex will use a 1.5 MW HyperCharger to refuel

There is a pervasive myth that electric cars must have five-minute refueling times, and travel 500 miles between charges, before they become mainstream. That has led to a race to find the absolute fastest way to charge an electric car.

Notwithstanding the idea of battery-swaps (or the demise of Better Place), we’ve seen a consistent escalation of charging speed levels. First, there was the Japanese-built CHAdeMO 50-kilowatt quick charge system. Then Tesla upped the ante with its 120-kilowatt Supercharger network. And now the latest entrant in the field of ultra-fast charging is the 1.5 megawatt Silex Hypercharger.

The Basics

The Silex HyperCharger concept is similar in application to both the CHAdeMO 50-kW quick charge and Tesla 120-kW Supercharger technology. All three take alternating current and convert it to high power direct current using powerful off-board systems. Like its predecessors, the Silex HyperCharger would deliver the power directly to the car’s battery pack via a specially-designed high-power connector.

According to its own press release, the Silex HyperCharger would be capable of operating at various power levels, offering “currents of up to 1000A and voltages that can vary between 360 and 1440 volts, depending on the type of vehicle that is charging.”

Hugely Power-Hungry

Tesla’s 120-kilowatt Supercharger may seem a little power-hungry compared to the CHAdeMO 50 kilowatt quick charge station. But that’s nothing compared to the Silex Hypercharger. Requiring 1.5 megawatts of power—enough to power between 350 and 450 average U.S. homes at the same time—Silex says the Hypercharger would have to be connected directly to local medium voltage power lines.

Connecting it to wires running to an average U.S. street would bring down the power for entire city blocks. Arranging connection directly to the medium-tension power grid will be both costly and complicated. Then there’s the issue of forcing electrons into a battery pack at those speeds and levels.

With every battery chemistry, there’s a physical limit to the number of electrons that can simultaneously pass through the battery’s cathode into the battery’s electrolyte, essentially due to the cathode’s surface area. When that limit is approached, the battery’s internal resistance rises, producing heat in the process. The higher the charging current, the higher the internal resistance, and the hotter the battery gets.

By increasing the surface area of a battery’s cathode and anode with nanotechnology and super-conductive materials like graphene, researchers have built super-dense batteries capable of charging at speeds an order of magnitude faster than the battery packs found in current production cars. But while the technology now exists to cater to ultra-fast charging, commercial application of the technology is still some time away.

Not Yet Built

But here’s the biggest problem with the Silex HyperCharger: like the Silex Chreos—the company’s high-power luxury sedan with incredible performance and range which is meant to use HyperCharger technology to refuel—the HyperCharger only exists inside Silex’s laboratories.

Quietly acknowledging this fact in its corporate press releases, Silex says the HyperCharging technology will undergo testing some time in 2014. Why is a company promoting a technology that it has yet to test in the real world? The answer is simple: investment. As Silex itself says, “Silex is open to third parties automotive manufacturers who are interested in adopting HyperCharging ports in their vehicles.”

That final line of Silex’s press release tells you everything you need to know about HyperCharging for now. It’s a nice dream, but it just isn’t reality yet.

New to EVs? Start here

  1. Seven Things To Know About Buying a Plug-In Car
    A few simple tips before you visit the dealership.
  2. Incentives for Plug-in Hybrids and Electric Cars
    Take advantage of credits and rebates to reduce EV costs.
  3. Buying Your First Home EV Charger
    You'll want a home charger. Here's how to buy the right one.