As electric vehicles become increasingly popular with consumers, the race to out invent is just beginning to rev up. Electric vehicles have ushered in a new generation of innovation, far outpacing that of previous generations. With acceleration times rivaling that of supercars, the battery range is the next frontier for auto manufacturers.

As one of the electric vehicle’s biggest hurdles, battery range remains a constant fear for drivers and passengers alike. Dreading the time the battery range hits “zero,” automakers invest heavily in improving existing battery technology.

One of the newest automakers, Rivian, has taken an outside approach to battery range. In particular, Rivian developed an electric vehicle system that includes an auxiliary battery module. Specifically, its recently issued patent details an “Electric Vehicle With Modular Removable Auxiliary Battery With Integrated Cooling.” The removable battery pack fits within the cargo area of a vehicle, such as a truck’s bed. Likely designed as an option for its highly anticipated Rivian R1T truck, this technology would extend the battery range significantly.

Rivian's Removable Battery Pack
U.S. Patent Publication No. 2019 / 0016231 A1 for Rivian’s Removable Battery Pack

Wait, Don’t Removable Battery Packs Already Exist?

You are correct in thinking that removable battery packs are generally known—and the examiner initially agreed. In fact, liquid-cooled battery packs are common in automotive applications. However, to overcome the close prior art, Rivian added an “inventive hook” to its claims. An “inventive hook” is at least one novel and non-obvious feature to your invention that has never been done before.

For Rivian, the presence of its integrated coolant system being unconnected from the conduit of a cooling system for the electric vehicle’s primary battery is its inventive hook. Despite Rivian’s initial claims being too broad, it was able to go back into its specification and pull out this important detail that was not found in the prior art.

It is a common drafting strategy to draft the claims of a patent application as broad as reasonably possible. Alternatively, the patent examiner focuses on narrowing the claims to your exact invention. After all, the patent office grants a patent holder a 20-year monopoly in the market.

Thus, it is crucial that your specification be as relevant and as detailed as possible to the structure of your invention and how it works. You never know what might be your “inventive hook.” Even the slightest detail, such as Rivian’s coolant system being unconnected from the primary battery, can be the difference between a granted and a rejected patent. It is important to note, that once you file an application, you cannot add new matter to an application. A new application, such as a continuation-in-part application, must be filed instead.


Overall, Rivian received a Notice of Allowance for its removable battery pack. By focusing on its inventive hook, Rivian successfully overcame the examiner’s rejections. Had Rivian submitted an application with a less detailed specification, its application may not have issued at all. Accordingly, it is extremely important that you find your inventive hook to overcome your invention’s prior art. Having a complete and well-drafted specification gives your application the best shot at maturing into a granted patent.

How long do you have to respond to a patent office action?

Generally, for most office actions you have three (3) months to respond from the date the office action issues. However, you can extend the deadline for another three (3) months by paying a fee.

How long has Rivian been in business?

The company was founded by its CEO Robert Scaringe in 2009.

What is prior art for patents?

Prior art is essentially anything that is published or publicly available that has come before your filing date of your application. The United States Patent and Trademark Office (USPTO) can use prior art to formulate rejections. If an examiner believes that the prior art teaches your invention, they will issue an office action.