Proterra Does a Tesla, Makes Rapid Charging Patents For Electric Busses Open Source

[EDIT] Since the original article was published, we’ve been contacted by Proterra with a few clarifications on its overhead charging technology, resulting in a few corrections to the article below.

When a new, revolutionary technology comes to market, the company which developed that technology usually works hard to protect its intellectual property through a series of carefully-worded patents. Any company seeking to use that technology in its own products must either license the technology from the patent holder (an additional revenue stream for the original patent holder), develop their own alternative, or face an expensive and lengthy court battle over patent infringement.

Traditional business logic states that protecting your patents means you have a chance of having an edge over your competitor. Sharing your patents means that you have to find some other way to stay ahead of the game.

The patents are for Proterra’s ‘FC’ DC quick charging technology.

In the past few years we’ve seen that wisdom challenged multiple times, as both Tesla Motors and then Toyota announced that they would make their respective zero emission vehicle patents available for competitors to use as a way to try to accelerate the development of electric vehicles and hydrogen fuel cell vehicles respectively.

Now, we can add a third company to that list: California company Proterra.

Known for its range of electric busses, Proterra has just announced that it will be making all of its patents relating to its overhead on-route fast charging technology available royalty-free to other companies in the public transportation sector. Just like the release of patents by Tesla and Toyota, Proterra says that it hopes making its technology available on an open-source basis will make it easier for more bus companies to switch from internal combustion engined vehicles to 100 percent electric vehicles.

In total, three patents are being made available on the royalty-free basis: U.S. Patents 8324858, 8829853 and 9352658. Each relates specifically to the overhead single-blade that sits atop Porterra’s busses and the matching DC overhead docking station that Proterra uses to rapidly charge its busses while passengers alight and mount the vehicle.

Proterra's unique charging system helps buses recharge quickly en-route.

Proterra’s unique charging system helps buses recharge quickly en-route.

How quick is the rapid charging technology? Quick: according to the patents, Proterra’s system can support voltages of between 250 volts and 1,000 volts at at currents of up to 1,400 amps. That translates to a charging power of up to 1.2 megawatts in theory, although at the moment Proterra’s current production vehicles operate at power rates of around 500 kW — equivalent to adding a full charge to Proterra’s specially-designed TerraVolt FC on-board battery pack in less than 10 minutes.

For comparison, Tesla’s Supercharger technology currently peaks out at around 135 kilowatts in ideal situations. The Combo CCS charge standard favored by most European and U.S. automakers and the most recent proposed upgrade to the CHAdeMO DC quick charge standard peaks out at a theoretical 150 kilowatts, although for now, most public charging stations using either standard are restricted to 50 kilowatts.

We should note however that at the time of writing, Proterra’s rapid charging technology isn’t designed for busses fitted with its XR long-distance battery pack. Instead, Proterra’s rapid charging technology While Proterra’s overhead charging technology can be used with busses fitted with both XR and XC battery packs, its headline 10-minute quick charge to full relates specifically to busses fitted with its FC battery pack. Smaller in capacity, chemistry and range than the XR long-distance battery pack, the 105 kWh FC battery pack is specially designed to allow rapid DC quick charging at rates of up to 500 kilowatts in 10 minutes, offering a real-world in-service range of around 63 miles per 10-minute quick charge.

We're curious to see how many companies take up Proterra on its offer.

We’re curious to see how many companies take up Proterra on its offer.

Proterra’s longer-range battery pack — which can offer 194 miles of range per charge from 330 kWh of storage can be used with the overhead charging system as a form of opportunistic charging, although with the battery pack being much larger, you can’t get the same 10-minute full charge from the system.

As we’ve seen from both Tesla and Toyota’s patent giveaway however, simply making the technology available doesn’t necessarily mean that it will be adopted by other companies. For that to happen, there has to be a lot of faith put in a rival’s technology, especially when such agreements usually come with some pretty strict requirements that must be met on both sides.

It’s not clear at the moment if Proterra intends to make more patents available in the future, but we think it’s a smart move that could, if we’re lucky, see a growth in electric buses around the world. And that has to beat today’s smelly diesel-powered models, right?


Want to keep up with the latest news in evolving transport? Don’t forget to follow Transport Evolved on Twitter, like us on Facebook and G+, and subscribe to our YouTube channel.

You can also support us directly as a monthly supporting member by visiting

Related News