Electric cars are quieter, do not pollute (if they use renewable energy), and can be one of the key components of sustainable mobility when moving away from fossil fuels. However, of course, they are not exempt from their own challenges: from the raw materials required for batteries to charging speed, there are still uncertainties to be resolved on their path to mass adoption. Fortunately, technological advancements are offering solutions, whether through battery alternatives or fast charging systems, improving the efficiency of electric cars. We will tell you more about the latter in this article. Has NASA found the key to fast charging for electric cars?
What you will find in this article:
How long does it take to charge an electric car?
For over a century, internal combustion engines have reigned supreme due to their high range and refueling speed. Unless you encounter a queue at the gas station, filling up a gasoline tank takes two or three minutes. Electric cars have more nuances. Generally, an electric vehicle (EV) can take between twenty minutes and twelve hours to charge fully. But what factors influence these times?
- Type of charging point: There are several types of charging points, defined by their power level, ranging from 1 to 3. Domestic charging points are usually type 1, while more powerful types 2 and 3 are reserved for public places.
- Battery type and capacity: Battery capacity ranges from 6 kWh for urban cars to 100 kWh for high-range models, although the average is usually between 40 and 50 kWh.
- Charge level: The initial and final 20% of the battery take the longest to charge.
- Ambient temperature: Charging speed is reduced in very low temperatures.
Interestingly, the last point is one that NASA has taken advantage of with a prototype developed in collaboration with Purdue University. In their case, they have chosen extreme cooling as an ally.
How to accelerate fast charging for an electric car
There is a physical obstacle to increasing charging power. It is the same principle behind the operation of a stove or a hairdryer: electricity passing through a resistance emits thermal radiation. If you have ever noticed how thick the “hose” of fast charging points is, there’s your answer: it requires numerous braided cables to avoid overloading and usually incorporates a cooling liquid. These charging points typically offer a power of 350 amperes.
The new system proposed by NASA can multiply the electric current carried by the power cables of an electric charging station by 4.6 times, operating smoothly at 1400 amperes. Technically, it could reach 2500 amperes. They have employed a temperature control system designed to operate under microgravity conditions in outer space to achieve this. The physical principle behind it is known as subcooled flow boiling. Thanks to this technology, they have dissipated up to 24.22 kilowatts of heat.
The prototype was developed by Purdue University, which has taken NASA’s research on subcooled flow boiling and applied it to the field of fast charging for electric cars. In fact, the university’s laboratory announced another fast-charging technology below five minutes in 2022.
How does subcooled flow boiling work?
You might be wondering how subcooled flow boiling exactly works. Well, this phenomenon occurs when a liquid is rapidly heated and begins to boil before reaching its average boiling temperature. If we place a pot of cold water on a ceramic hob or gas stove, the water will gradually heat up. As the water heats up, there comes a point where the surface temperature becomes high enough to form vapor bubbles, even before the entire liquid reaches its boiling temperature.
These vapor bubbles that form in water colder than normal are called “boiling nuclei.” As heat is transferred to the surrounding water, these vapor bubbles grow and detach from the surface, dissipating heat with them.
Subcooled flow occurs when a moving liquid, such as water flowing through a pipe, is cooled below its normal boiling temperature before it starts to boil. This can happen when there is a rapid transfer of heat to the liquid or when the liquid is under high-pressure conditions.
It is worth noting that this technology will initially be intended for space missions and the colonization of Mars. Furthermore, all elements – from the battery to the charging station and power cable – must be prepared for that level of power. However, who knows how long it will take until we see it applied to fast charging for electric cars here on our planet, contributing to a more sustainable economy.