This is a part of the EV Innovation Intelligence series
In its early days, charging an electric vehicle could take 8-10 hours. Surely no one would wait that long for a vehicle to be charged, unless of course it is charged while the owner is doing something else – sleeping, for instance, or at work.
Most EVs used to charged at home or at free public charging stations. Most of these public chargers were limited to 240-volt, or level 2 charging, while home chargers can even be limited to 110-volt, or level 1 charging.
The long charging time was obviously one of the real challenges for a battery based electric vehicle. A DC fast charger on the other hand takes the charging level way beyond these limits, and provides the quickest charging system. With newer Li-ion batteries and advanced charging technologies, you can in theory charge a car in as little as 15 minutes today (or 4C in industry lingo, where the numeral = 60/(number of minutes taken for a charge)).
Our specialty focus areas include
There are even talks of flash charging technologies that are faster than the above mentioned one.
Here are some updates:
- 480 km range in just 10 minutes of charge! Penn State University’s engineers have developed a new EV battery which takes 10 minutes to charge – Jan, 2020
- Charging a car battery in 5 Minutes – Several companies have built lithium-ion batteries that can fully charge in a matter of minutes, but most of these are in the pre-commercial stages. These will most likely be used in racing cars. For instance, Formula E officials announced the specs for the third generation of all-electric race cars that will debut on the motorway in 2022, and these Formula E cars will use extremely fast charging stations that can fully charge a Tesla Model S battery in about 10 minutes.
- New Flash Battery Allows Charging in 5 Minutes; Technology Scalable to EVs – A May 2019 report mentioned that the Israeli company StoreDot has introduced FlashBattery, a quick-charging battery that can fully charge in 5 minutes. The technology uses novel materials replacing the active graphite with metalloids such as Silicon, combined with proprietary organic compounds that protect the active materials during fast charging.
Current status
The current data point to ultra-fast charging (even less than 10 minutes available), but only in very select cases.
- ABB’s TOSA is of these, for buses. It claims to be the world’s fastest flash-charging connection technology, which at select passenger stops connects the bus to charging infrastructure and in 15 seconds batteries are charged with a 600-kilowatt power boost at every stop and charge completely at the terminal stations in 3-4 minutes. The charging takes place by an overhead pantograph connection.
Cost
The high cost of the battery could be a big challenge for ultra-fast charging. Super-fast charging will need battery chemistries that are premium and high-end, and some of these chemistries could cost 3 or even five times as much as the prominent Li-ion battery chemistries used.
In the case of the purchase of the DC fast charging equipment, the cost varies depending on the manufacturer, the unit specifications as well as the number of units ordered. While the price of chargers has been declining, most stakeholders contributing to this research cite 2015 prices cited range from $25,000 to $40,000 per unit. The installation cost varies depending on
- The availability of a suitable source of 3-phase electricity in close proximity
- The civil work required on-site
- The importance of the aesthetics to the operator
- The time of the year at which the installation work is performed (a consideration in all provinces except BC)
- The organization managing the project.
Based on the information gathered from Canadian stakeholders involved in the deployment of DCFCs, the installation cost can vary widely from $15,000 to over $60,000. This does not include the cost or installation of peripheral equipment, such as solar carports and heating pads, to ensure the space is accessible at all times to EV owners.
Safety
We are talking about a large amount of power being used ( sometimes as high as 1 MW). Such high wattage charging brings with it its own technical and safety challenges.
In addition to infra such as transformers and switchgear present at the charging facility, ultra-fast charging could also need significant safety infrastructure to be installed at these facilities.
Ultra-fast charging Li-ion must meet these conditions to minimize stress and maintain safety:
- The battery must be designed to accept an ultra-fast charge.
- The battery must be in good condition. Aging slows charge acceptance.
- Ultra-fast charging only works to 70 percent state-of-charge (SoC); topping charge takes longer.
- All cells must have low resistance and be well balanced in capacity. Weak cells are exposed to more stress than strong ones. This worsens the condition of the weak cells further.
- Charge at a moderate temperature. Low temperature slows the intercalation of lithium-ions, causing an energy over-supply. Unabsorbed energy turns into gas buildup, heat, and lithium plating. Some large batteries include heating and cooling systems to protect the battery.
- Increasing the charge current is simple — assessing how much energy a battery can absorb is more difficult.
A well-designed ultra-fast charger evaluates the battery condition to match the charge current with the abortion rate. The charger should also adjust to temperature and observe cell balance. Furthermore, the recommended ultra-fast charger should have three settings: Overnight Charge (0.5C); Fast Charge (0.8–1C), and Ultra-fast Charge (above 1C). This allows the user to limit ultra-fast charging to only when needed and at a suitable temperature. While such a charger may not yet exist, basic battery knowledge and common sense should prevail when charging batteries in an unconventional way.
Material challenges
While some battery chemistry are in fact suited for ultra fast charging, it is not clear about the limits of materials, and also the overall lifetime of the battery when it gets such ultra-fast charging very frequently.
| Type | Chemistry | C rate | Time | Temperatures |
Charge termination
|
| Slow charger | NiCd Lead acid |
0.1C | 14h | 0ºC to 45ºC (32ºF to 113ºF) |
Continuous low charge or fixed timer. Subject to overcharge. Remove battery when charged.
|
| Rapid charger | NiCd, NiMH, Li-ion |
0.3-0.5C | 3-6h | 10ºC to 45ºC (50ºF to 113ºF) |
Senses battery by voltage, current, temperature and time-out timer.
|
| Fast charger | NiCd, NiMH, Li-ion |
1C | 1h+ | 10ºC to 45ºC (50ºF to 113ºF) |
Same as a rapid charger with faster service.
|
| Ultra-fast charger | Li-ion, NiCd, NiMH | 1-10C | 10-60 minutes | 10ºC to 45ºC (50ºF to 113ºF) |
Applies ultra-fast charge to 70% SoC; limited to specialty batteries.
|
Timelines
Depending on who you talk to and the geography we are referring to, ultra-fast or even fast charging could be round the corner or could take over five years to become commonplace.
Charging protocols
The main charging protocols ChAedemo, Tesla protocol and other charging protocols need to evolve in order to accommodate fast charging. Currently, there are three dominant standards for fast charging: CHAdeMO, CCS and GB/T. These standards are partially compliant with IEC 61851 standard, or with an equivalent standard as the GB/T 18487. They differ from one another in the connector cable employed, communication protocol, or security procedures. Nevertheless, maintaining the general requirements for a DC charger. The output power specifications for the DC chargers have been updated from the first versions of the standards and have been associated with Fast and Ultra-fast terms according to the power level increases. However, these kinds of denominations have caused some confusion.
CHAdeMO and CCS have defined power charging levels above 350 kW and output voltages up to 1 kV, beginning the standardization process for heavy-duty vehicles fast charging, like buses and trucks. This could also improve the charging times of light vehicles. It also means that theoretically, a Tesla Model S battery could be recharged from 0 to 80% in less than 14 minutes, but as mentioned before, the charging time depends on the battery characteristics and its capacity to handle high charging currents according to the thermal management system capabilities present at the BEV.
Software
The software solutions around fast charging also need to evolve fast enough to ensure that the whole charging, monitoring and control process is seamless and efficient.
This is a part of the EV Innovation Intelligence series
Posts in the series
Tesla’s Valuation | EV’s in different countries | Purpose built EVs | Mainstream Fuel Cells | IT in Emobility | EVs versus ICEs | Advent of China in Emobility | Charging vs Swapping | Micromobility & EVs | Electric Aviation | Li-ion alternatives | Million Mile Battery | Battery Startups versus Giants | Sales & Financing Models | Ultrafast Charging a Norm | Heavy Electric Vehicles | Material Sciences in Emobility | Lithium Scarcity | Solar Power in EV Ecosystem | EV Manufacturing Paradigm | Innovations in Motors | EV Startups – a speciality | Oil Companies’ Strategies | EV Adoption Paths | Covid-19 affect on the EV Industry |
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