Tesla Aims For 5-Minute EV Recharge, Tesla CTO States
This article was first published on Kompulsa — GE.
JB Straubel, the CTO of Tesla Motors, has said that he thinks Tesla will be able to charge electric car batteries in five to ten minutes before too long (without battery swapping).
He pointed out some of the challenges associated with this, but the fact that charge times have gotten down to 20 minutes already should give you some hope.
The challenges include: Tesla Motors’ vehicles — the Roadster and Model S — both have very large battery banks, and therefore would require an enormous current to charge in just a few minutes.
This large current can be provided with a Level 3 charging station which has built-in, powerful batteries to supply that current (and then the charging station batteries can recharge over the course of the day, until the next car that needs fast charging comes along).
The battery design also needs to be able to tolerate or limit the temperature rise caused by fast charging (maybe by increasing efficiency) — larger currents, in general, tend to cause more heat generation, in basically every device.
It is technically possible for prototype lithium-ion batteries to charge in less than a minute. However, commercialization of these technologies is a different story.
“It’s not going to happen in a year from now. It’s going to be hard. But I think we can get down to five to 10 minutes,” Straubel said in an interview with MIT Technology Review. He noted that the current superchargers, which deliver 120 kilowatts of electricity, “seemed pretty crazy even 10 years ago.”
JB Straubel’s statement didn’t come long after Tesla Motors announced upgrades to its Supercharger network, which would enable 20-minute charging.
Straubel said that Tesla Motors was able to achieve this because it designs and builds its own equipment, instead of just buying parts from third-party manufacturers as most manufacturers do (which doesn’t qualify as innovation).
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It always comes down to doing the work yourself rather than outsourcing.
Theoretically possible to charge in one minute?! That seems so wildly incredible. However if it is true that would be great.
The idea of using batteries at charging stations so quick charges can be done seems more expensive than wiring the station up properly to the grid. Do slightly thicker wires really cost more than keeping mountains of batteries on standby?
Well how many cars do you imagine to be charged simultaneously? Go for ten and you are already in the megawatt region. Actually 1.2MW. And that it not really a worst case scenario, that might be easily twice that in the near future at peak times. The US as far as I know does use only half the voltage then most other countries this makes the amperage needed, and therefore the wire diameter, quiet massive. It also would not be very grid friendly to have huge fluctuations in demand. A battery buffer would spread out that load over day and allows to buy the electricity at points of the day were it is comparably cheap. That might make sense for a company like Tesla which does have somewhat strong links with a company, SolarCity, that might develop towards being a Utility of some sort.
Also you need to have DC voltage for supercharging. The grid tied converter which charges the batteries can be scaled down and put to a higher utilization.
Like Japan and some other countries our ‘common’ outlet voltage is 120 vac. Europe and other parts of the world use 240 vac.
Move back to the distribution system and we’ve got 7.2, 12.47, 25, and 34.5 kV stuff available. We can pull high voltage into a rapid charging station.
“The modern distribution system begins as the primary circuit leaves the sub-station and ends as the secondary service enters the customer’s meter socket by way of a service drop.
Distribution circuits serve many customers. The voltage used is
appropriate for the shorter distance and varies from 2,300 to about 35,000 volts depending on utility standard practice, distance, and load to be served. Distribution circuits are fed from a transformer located in an electrical substation, where the voltage is reduced from the high values used for power transmission.
Conductors for distribution may be carried on overhead pole lines, or in densely-populated areas, buried underground. Urban and suburban distribution is done with three-phase systems to serve both residential, commercial, and industrial loads.
Only large consumers are fed directly from distribution voltages;
most utility customers are connected to a transformer, which reduces the distribution voltage to the relatively low voltage used by lighting and interior wiring systems.”
Wiki
“Also you need to have DC voltage for supercharging.”
All battery charging is done with DC. It’s just a matter of whether the car’s built-in charge or an external, larger charger does the conversion from AC to DC and tweaks the voltage to match the battery bank.
Yes, I know. I was referring to the supercharging systems Tesla uses, they are DC 360V supplying over 250A to achieve the 90kW charging.
And I don’t see a technical and economical feasible way to realize a 90kW, let alone a 120kW, transfer with the AC-DC conversion taking place in the car. It could be done but it certainly wouldn’t make the car any cheaper and on the outside you still would need to create some sort of suitable AC voltage, 120V or 240V are to low and 7.2kV might be a bit over the top.
With the superchargers the DC conversion is done outside the car and transfered directly to the battery pack……no AC to DC conversion inside the car with supercharging…