After more than a hundred years of fuelling their vehicles in under fifteen minutes for a 400 km range, consumers are baulking at the idea of having to wait 30 to 40 minutes (At best) for the same range in an Electric Vehicle. Various studies into consumerism quote this as one of the key inhibitors to the growth of e-Mobility.
Any charging infrastructure must be tailored to typical user behavior during long trips and offer an appropriate ratio of driving time to rest stops. During a typical break time of 15 to 20 minutes it is reasonable for drivers to expect to be able to charge an EV’s battery for roughly 400 kilometers.
Image Source: Ionity
Today’s DC charging stations for electric cars commonly work on about 400V. With a typical charging power of about 50 kW, this equates to a charging time for a 400 km range of about 80 minutes.
There are numerous challenges in significantly reducing the time to charge, not least of all being the voltage at which the current generation of EVs charge.
Increasing the charger’s output voltage to cut the time to charge
While it is possible to increase the output power of a 400V charging station, the capacity of the conductive pins in the charging plug would still restrict the output power to roughly 100 kW. Under these conditions, it would take about 40 minutes to transfer the energy for 400 km worth of driving.
The limited power capacity of the pins can be improved significantly by cooling the charging plugs, which then extends the power of the 400V charger to the point where the target range can be achieved with a charging time of approximately 30 minutes.
But, while 30 minutes is an improvement it still does not meet consumers’ expectations. A shift to a higher voltage is therefore inevitable in the quest to achieve acceptable charging times.
The rationale behind this move is explained by the formula for electrical energy: E = U x I x t, where U is the voltage, I the current and t the time.
The charging time t = E / (U x I) can thus be achieved with a constant current I by increasing voltage U. By switching to a two-fold higher voltage of approximately 800V, the charging time can theoretically be reduced to about 15 minutes with the same electrical load on the charging pins.
If one takes into account the paying process, the goal of “charging like filling up” is thus nearly within reach.
The first mass production OEM to capitalize on the benefits of 800V electrification will be Porsche with its first fulltime EV, the Taycan, scheduled for launch in 2019.
Porsche’s Turbo Charging for EVs
The first fast charging park to be equipped with Porsche’s 800V Turbo Chargers is located at the Berlin-Adlershof Technology Park. This car park has four customer parking spaces that are equipped with Porsche charging technology. Of those four spaces, two of them have 800V Turbo Chargers developed by Porsche Engineering Services GmbH.
The Porsche charging structure uses the Combined Charging System (CCS) connector and can split its 800V throughput into two 400V plugs. At the 400V level a typical EV can charge to a range of 400 km in 40 to 80 minutes. However, once the voltage level is increased to 800V, the charging time comes down to less than 20 minutes for the same range.
Seen as a pilot project, Porsche intends to use the site as a test facility, gathering experience of the technology before rolling it out to other Porsche Centers. And Porsche won’t be limiting the Turbo Chargers to its cars only.
All electric vehicles will be able to charge for free during normal operating hours at the Porsche Center in Berlin-Adlershof, with an app giving users detailed information about the charging process.
According to Porsche CEO, Oliver Blume: “We are in contact with other manufacturers and suppliers around the world to build a fast-charging network. Everybody has the same need. It sounds easy but getting the details agreed is hard. We already have the clear technical concept. It can even work with Teslas, with an adapter.”
Both Volkswagen (with the Budd-e all electric van concept) and Mercedes (with the launch of Generation EQ) have confirmed that their vehicles will be capable of charging at power levels up to 150 KW for fast charging. Both OEMs have also confirmed that they envisage a future step-up to 300+ kW and 800V.
In America, Porsche will roll out 350 kW Turbo Charging to all of its 189 dealerships.
Obviously with more manufacturers adopting the 800V standard the network will need to expand to service the needs of the consumer. This is exactly what pioneering technology provider ABB intends to do with its Terra HP High Power Charge system.
ABB’s Terra HP Charge system is designed for wide scale deployment
Ideally suited for use at highway rest stops and petrol stations, Terra HP’s high capacity has the ability to charge both 400V and 800V cars at full power, with a charge time as little as 8 minutes for a range of 200 km.
Demonstrating confidence in ABB’s solution, Electrify America, considered to be the largest electric vehicle infrastructure project to date in the United States, will install Terra HPs at more than 100 Walmart locations across 34 states next year.
Furthermore, the project aims to spend a total of $2 billion over the next 10 years in electric vehicle infrastructure and education, installing chargers on highway routes at intervals of no more than 195 kilometers.
A 375 A output single-power cabinet can charge a 400V car continuously at a full 150 kW. The addition of Dynamic DC power sharing technology, allows a two-power cabinet charging system to charge a couple of EVs simultaneously, with up to 350 kW and 500 A, while dynamically optimizing the available grid connection and the power delivery to the two vehicles.
To further improve performance for charging operators, Terra HP delivers the highest uptime, reduced redundancy on power and communication, and individually cooled charging cables.
What's more, Terra HP provides the additional benefit of ABB Ability Connected Services, which deliver enhanced functionality, including the ability to easily connect chargers to back offices, payment platforms or smart grids. Equally important, remote diagnostics, repair and over-the-air software updates, minimize downtime and keep running costs low.
For customers, the Terra HP delivers a number of benefits, including an intuitive, easy to use touchscreen display and multiple payment options.
Another operator focused on the expansion of the fast-charger network is ChargePoint who, with the roll out of their ultra-fast DC Express Plus charging solution, will be able to support an output of up to 400, kW accommodating charging voltages from 200V to 1000V; including today’s 400V cars and 750V buses, and tomorrow’s 800V cars.
A novel modular approach to charge stations
A modular platform designed for businesses and charging centers along major roadways or transit depots, Express Plus can charge the current generation of EVs, such as the Chevy Bolt and Tesla’s Model 3, at their maximum rate. What’s more, the system is also capable of delivering the maximum charging speed to future EVs running off 800V and delivering 350+ kW.
The latest ChargePoint system allows charging site operators to design infrastructure for the long term and incrementally build this out to meet driver demand without any stranded investment along the way. The product intelligently allocates power among vehicles based on each battery’s state of charge (SoC) and instantaneous maximum charge rate, so every car charges as fast as possible, getting drivers back on the road quickly while making efficient use of the power available at each site.
The ChargePoint Express Plus architecture consists of three modular building blocks that can be configured to meet the exact requirements at any site and scale incrementally as demand for charging increases:
1. Power modules are the basic building blocks of the architecture. Each module is a self-contained AC to DC power conversion system that operates with an output of between 200 and 1000V.
2. The charge stations can support up to three flexible, lightweight cables compatible with all standard connector types. Each station houses two power modules and can connect with a ‘Power Cube’ to deliver up to 400 kW to a single vehicle. There’s a 10-inch LCD touchscreen for driver interaction, 20-inch wide-format LED display for notifications, cameras, area lighting, and WiFi and Bluetooth connectivity. Built-in cellular networking enables remote management through ChargePoint Cloud Services.
3. Power Cubes house up to 16 power modules in an attractive format that services up to eight Express Plus Stations in a fully integrated system. Power cubes have AC input, DC outputs, cooling, system controls and networking for remote diagnostics and management. Power consumption is managed within a site’s available capacity while minimizing the impact on vehicle charging rates. Power management and high-efficiency power conversion (more than 96% efficiency) reduce electricity costs and wasted energy. Fault-tolerant design, instrumentation for remote monitoring, intelligent diagnostics and machine learning techniques work together to predictively prevent failures and ensure high availability.
With consumer convenience top-of-mind, another supplier, Continental, developed its “AllCharge” technology as a ‘universal charger’ system capable of supplying a maximum of 350 kW at up to 800V via the EV’s powertrain.
Continental’s universal 800V system’s flexibility lies within the EV
Recharging an electric vehicle still leaves something to be desired in terms of everyday user-friendliness. For example the selected charging station may only offer slow single-phase AC charging or alternatively, if it does offer high-speed DC charging, the vehicle itself may not be equipped with the necessary technology to support this.
Since constant AC/DC switching at different voltages is already an inherent feature of the electric powertrain, the system is already capable of functioning as a charging system. By exploiting these capabilities, Continental provides interoperability with different charging technologies using an onboard, vehicle-based solution.
Continental has turned the existing electric powertrain into a ‘charger,’ dubbed the ‘AllCharge’, capable of both AC and DC modes, using a single cable connector:
• In the case of AC current, the current flows from the charging station via the electric motor to the inverter, where it is converted into DC current before being supplied to the battery.
• In the case of DC current, the current from the charging station flows directly through the inverter to the battery.
The system allows operators to charge their vehicle at any charging station, at an output rate of up to 800V and 350 kW, while also providing drivers 230V of AC power for onboard use. Designed with V2D (vehicle-to-device) capability in mind, the vehicle battery can also be used to power mobile electrical devices ranging from a laptop to a refrigerator or an electric drill.
According to Dr. Martin Brüll, Continental’s expert responsible for the new charging system, with 350 kW DC charging, a five minute charge can deliver approximately 150 km of driving range.
The trend is clear to see: 800V and 350+ kW chargers are cutting the time to charge, to levels where consumers are comfortable to tackle long cross country trips, but there are is new class of battery that may take this a step further: Solid state batteries.
Fisker’s 800V EMotion with solid state battery
Due for launch in 2019, the Fisker EMotion is based on a bespoke 800V technology, developed together with strategic partner Ricardo. The partnership has come up with a proprietary 800V Ultra Charger, 800V Battery Pack and e-axle powertrain.
The EMotion will be equipped with a 800V, 145 kWh battery (initially made up of 21700 LG Chem cells), good for over 644 km per charge; with a range of 200 km achieved within 9 minutes of charging.
First specified with a solid-state battery, the technology won’t be ready by the car’s target launch date, so the LG Chem lithium-ion battery pack is being used for now. Despite delays in commercializing the technology Fisker is confident that the system will be in the car early next decade, allowing for a much smaller battery pack with a greater range and reduced charge times of just a few minutes.
As demonstarted by the examples above, raising a charge station’s voltage to 800V achieves a significant reduction in charging times. Even working with the currently available cell chemistry, charging times are possible that would fit perfectly well with the travel profile of long-distance trips.
What’s more, by adopting a holistic approach to the system design - from the grid connection to the charging socket - a well-planned topology can also achieve significant savings in the cost-driving components, where existing infrastructure is used as a base: According to Porsche, a comparison of the specific costs (euro per kilowatt of charging power), show that a high-power charging infrastructure can be significantly less expensive than the currently available 400V rapid-charging infrastructure.
In twenty years’ time the industry may just look back at this early roll out of 800V electrification as one of the defining moments of eMobility.
Sources:
• Nicolas Zart; Clean Technica; Porsche Inches Into Superfast Charging 800 Volt Chargers; July 2018https://cleantechnica.com/2018/07/17/porsche-claims-400-volts-for-400-kilometers-with-superfast-800-volt-chargers/
• Nancy Owano; Tech Explore; ABB unveils EV charger can add 200 km of range in 8 minutes; May 2018; https://techxplore.com/news/2018-05-abb-unveils-ev-charger-km.html
• Zac Estrada; The Verge; Fisker’s ‘autonomous’ EMotion electric car promises 400 miles of range; January 2018; https://www.theverge.com/2018/1/9/16867184/fisker-emotion-electric-luxury-car-lidar-autonomous-ces-2018
• Fred Lambert; Electrek; Porsche’s ultra-fast charging infrastructure for the Mission E will also work with Tesla, says CEO; October 2017; https://electrek.co/2016/10/03/porsches-ultra-fast-charging-infrastructure-for-the-mission-e-will-also-work-with-tesla-says-ceo/
• ABB; ABB powers e-mobility with launch of first 350 kW high power car charger; October 2017; http://www.abb.com/cawp/seitp202/c2ed43a8ef2e1de2c12581ae002d26b8.aspx
• Mark Kane; Inside EVs; Continental AllCharge enables 800V, 350 kW Charging; June 2017; https://insideevs.com/continental-allcharge-enables-800v-350-kw-charging/