United States-based auto companies are leading the industry in electrified vehicle patents, with second place going to Japan.

After adding up the number of U.S. patents relating to electrified vehicles (EVs), IPWatchdog said that a third of all patents come from two of the largest auto manufacturers in the U.S. The patents encompassed in the count specifically mention EVs, including hybrids, battery electric and plug-in hybrid vehicles.

IPWatchdog tracks patents, copyrights and trademarks, as well as news and information surrounding innovation and intellectually property. Its rankings includes Japanese companies doing business in the U.S., but true U.S. based companies are atop its list.

“As we continue to try tracking how American auto development stacks up against the rest of the world … EVs are another area where we’ve been noting a lot of activity in both research and development,” IPWatchdog said. “It’s clear that electric vehicles won’t be completely squeezing fuel cell technology out of the market but many auto manufacturers are focused on developing lithium-ion battery technologies for cars. We’ve even noted innovation in the field of wireless induction charging for vehicles, eliminating the need to plug into an outlet at all.”

The four most innovative companies in the “EV” segment, says IPWatchdog lumping electrified vehicles into “electric vehicle” category are as follows:

4. Toyota

U.S. Patents: 201

2016 Toyota Prius

2016 Toyota Prius

With 201 U.S. patents, Toyota has filed the fourth highest amount of EV-specific copyrights. This includes patents for “Electric Vehicle Theft Preventing Device” and “Diversion of Energy from Regenerative Braking.”

Not all of the patents are physical components, though. One example of this is Toyota’s patent for the “System and Method for a One-Time Departure Schedule Setup for Charging Battery-Electric Vehicles.”

“This system is designed to allow EV owners who utilize on-board vehicle tools for scheduling charging an improved and easier ability to create a one-time edit in the primary charging schedule,” noted IPWatchdog.

3. Honda

U.S. Patents: 272

Among Honda’s 272 patents is “Charging of Electric Vehicles Based on Historical Clean Energy Profiles,” which sources only renewable energy for recharging, along with several innovations for electrified motorcycles. One of these, Patent No. 9108519, is for a display that details information on the motorcycle’s charging speed and charge connection.

2. General Motors

U.S. Patents: 370

The Chevrolet Volt, currently ranked in the U.S. as the top-selling plug-in hybrid, certainly benefits from many of the GM’s innovations. IPWatchdog lists three of GM’s patents, the “Compact Electric Range Extender for an Electric Vehicle,” the “Electric Vehicle Pedestrian Warning System” and the “Method to Facilitate Opportunity Charging of an Electric Vehicle,” explained below.

“The method for charging a high-voltage battery of a vehicle protected here involves a monitoring, on a vehicle owner’s handheld device, the geographical location of the vehicle and transmitting that information to a control module, resolving the location of the vehicle at a specific power outlet of a charging station and transmitting that location to a central server and, at the central server, providing billing and access to the remote charging site,” IPWatchdog said. “This system also includes a mechanism allowing a charging site owner to create credit and debit accounts for individual vehicle owners.”

1. Ford

U.S. Patents: 459

2014 Ford C-Max Energi cutaway

2014 Ford C-Max Energi

Some may be surprised to see that Ford Motor Co. tops this list. Though the company’s Fusion Energi and C-Max Energi post double digit numbers for market share, the total number of units sold still falls significantly behind top sellers like the Toyota Prius or Chevy Volt.

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But the sheer number of patents Ford owns is staggering. Its last count of 459 U.S. patents makes up 18 percent of all patents tallied. Among them, IPWatchdog lists Patent No. 9033075: “Auto-Seek Electrical Connection for a Plug-In Hybrid Electric Vehicle.”

This patent details “a method for controlling a battery-powered vehicle by controlling an electric traction motor to incrementally advance position of the vehicle towards a stationary charging element, controlling power steering to steer the vehicle towards the element and controlling the suspension to align a charging connector with the charging element,” explained IPWatchdog. “This innovation is intended to make sure that a vehicle is charged if an owner forgets to plug it in overnight.”