2:26-cv-00741
Bunker Hill Tech LLC v. Volvo Car Corp
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Bunker Hill Technologies, LLC (Texas)
- Defendant: Volvo Car Corporation (Sweden); Volvo Car USA LLC (Delaware); and Polestar Performance AB (Sweden)
- Plaintiff's Counsel: Nelson Bumgardner Conroy PC
- Case Identification: 2:26-cv-00741, E.D. Tex., 08/24/2026
- Venue Allegations: Plaintiff alleges venue is proper for Volvo Car Corporation and Polestar Performance AB as foreign corporations that may be sued in any judicial district. Venue for Volvo Car USA LLC is based on its alleged regular and established place of business in Northlake, Texas, within the district, and its commission of infringing acts there.
- Core Dispute: Plaintiff alleges that Defendants' electric and hybrid-electric vehicles infringe six U.S. patents related to onboard power electronics, energy transfer systems, and charging methods.
- Technical Context: The technology at issue concerns systems and methods for charging electric vehicle batteries, focusing on the use of onboard power electronics to manage energy transfer from external sources.
- Key Procedural History: The complaint alleges that Plaintiff's licensing agent put Defendants Volvo and Polestar on notice of the asserted patents and alleged infringement prior to filing the lawsuit. Communications with Volvo are alleged to have started as early as October 14, 2025, and included providing claim charts and participating in a telephonic conference.
Case Timeline
| Date | Event |
|---|---|
| 2008-10-22 | Earliest Priority Date ('121, '439, '023 Patents) |
| 2009-08-31 | Earliest Priority Date ('884, '582 Patents) |
| 2009-12-18 | Earliest Priority Date ('365 Patent) |
| 2011-10-04 | U.S. Patent No. 8,030,884 Issues |
| 2013-07-16 | U.S. Patent No. 8,487,582 Issues |
| 2017-11-07 | U.S. Patent No. 9,809,121 Issues |
| 2018-03-13 | U.S. Patent No. 9,914,365 Issues |
| 2018-05-22 | U.S. Patent No. 9,975,439 Issues |
| 2020-03-31 | U.S. Patent No. 10,604,023 Issues |
| 2025-10-14 | Alleged initial communication with Volvo regarding potential license |
| 2026-04-07 | Alleged letter with claim charts sent to Volvo |
| 2026-05-04 | Alleged response from Volvo requesting claim charts |
| 2026-07-09 | Alleged telephonic conference between Plaintiff and Volvo |
| 2026-08-24 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 8,030,884 - "Apparatus for transferring energy using onboard power electronics and method of manufacturing same"
- Issued: October 4, 2011.
The Invention Explained
- Problem Addressed: The patent's background section identifies the problem of added cost, weight, and component complexity associated with dedicated onboard chargers for electric and hybrid vehicles ʼ884 Patent, col. 1:44-62
- The Patented Solution: The invention proposes a system that reuses the vehicle's existing traction power electronics, such as the motor inverter, to also function as a battery charger when the vehicle is parked ʼ884 Patent, abstract A controller manages this dual-functionality, monitoring the energy transfer from an external source and controlling the power electronics to regulate the charge supplied to the battery, thereby eliminating the need for a separate onboard charging apparatus ʼ884 Patent, col. 2:5-13 ʼ884 Patent, abstract
- Technical Importance: This dual-use approach for power electronics was aimed at reducing the cost, weight, and complexity of electric vehicles, which were significant barriers to market adoption at the time of the invention ʼ884 Patent, col. 1:56-62
Key Claims at a Glance
- The complaint asserts at least independent claim 20 Compl. ¶86
- The essential elements of independent claim 20 include:
- A "charge bus" for receiving charging energy from a voltage source.
- An "energy storage device" (e.g., a battery) coupled to the charge bus.
- A "first bi-directional voltage modification assembly" also coupled to the charge bus.
- A "controller" configured to monitor the energy transfer, compare it to a threshold (like battery voltage), and control the bi-directional assembly to modify the charging voltage or current after the threshold is crossed.
U.S. Patent No. 8,487,582 - "Apparatus for transferring energy using onboard power electronics and method of manufacturing same"
- Issued: July 16, 2013.
The Invention Explained
- Problem Addressed: Like its parent '884 patent, this patent addresses the need for cost-effective and efficient onboard charging systems for electric vehicles '582 Patent, col. 1:16-57
- The Patented Solution: The invention describes a charging apparatus that includes a charge bus specifically "coupleable to a high-impedance voltage source" (e.g., a standard wall outlet) '582 Patent, abstract A controller monitors the energy transfer from this source and modifies the charging voltage and current supplied to the vehicle's energy storage device, enabling a two-stage charging process where an initial rapid charge is limited by the source's impedance, followed by a controlled charge managed by the vehicle's onboard electronics '582 Patent, col. 4:39-56
- Technical Importance: The technology provides a method for more flexible and efficient charging from common, high-impedance residential power sources without requiring specialized off-board equipment '582 Patent, col. 3:58-67
Key Claims at a Glance
- The complaint asserts at least independent claim 1 Compl. ¶103
- The essential elements of independent claim 1 include:
- An "energy storage device" outputting a DC voltage.
- A "bi-directional voltage modification assembly" coupled to the energy storage device.
- A "charge bus" coupled to both the storage device and the modification assembly, where the bus is coupleable to a "high-impedance voltage source".
- A "controller" configured to monitor the transfer of charging energy from the high-impedance source and modify the voltage/current supplied to the energy storage device based on that monitored transfer.
U.S. Patent No. 9,809,121 - "Apparatus for energy transfer using converter and method of manufacturing same"
- Issued: November 7, 2017 Compl. ¶68
Technology Synopsis
The '121 patent describes a vehicle charging architecture featuring a connection system that can utilize both a first connection (e.g., DC fast charging) and a second connection (e.g., AC charging) '121 Patent, claim 7 The system employs a plurality of DC converters configured to first boost an input voltage to an intermediate level and then buck that intermediate voltage to an output voltage suitable for charging the vehicle's energy storage device, allowing for flexible power conversion from different external sources '121 Patent, abstract
Asserted Claims
At least independent claim 7 Compl. ¶120
Accused Features
The complaint alleges that the accused vehicles' charging system, which supports both AC and DC charging inputs and utilizes multiple DC converters for power management, infringes the '121 patent Compl. ¶¶124-126
U.S. Patent No. 9,914,365 - "Apparatus and method for rapid charging using shared power electronics"
- Issued: March 13, 2018 Compl. ¶69
Technology Synopsis
The asserted claims of the '365 patent describe a single-vehicle charging system capable of handling both DC and AC external charging sources '365 Patent, claim 1 The system architecture includes an AC/DC converter for the AC connection and a plurality of DC converters that are configured to boost an input voltage to an intermediate voltage and subsequently buck it to a final output voltage for charging the energy storage device '365 Patent, claim 1
Asserted Claims
At least independent claim 1 Compl. ¶137
Accused Features
The complaint targets the accused vehicles' charging system, alleging it comprises the claimed energy storage device, a connection system for both AC and DC charging, an AC/DC converter, and a plurality of DC converters that manage the charging process Compl. ¶¶140-143
U.S. Patent No. 9,975,439 - "Apparatus for energy transfer using converter and method of manufacturing same"
- Issued: May 22, 2018 Compl. ¶70
Technology Synopsis
The '439 patent discloses an integrated vehicle power system that combines a traction drive with an onboard charging system '439 Patent, abstract The architecture includes an energy storage device, a first voltage converter, a traction drive (with an inverter and motor), and an onboard charging system with a receptacle and additional voltage converters (a second to boost, a third to buck) to manage power from an external source to the battery '439 Patent, claim 1
Asserted Claims
At least independent claim 1 Compl. ¶154
Accused Features
The infringement allegations focus on the accused vehicles' integrated powertrain, which is alleged to contain the claimed energy storage device, multiple voltage converters, a traction drive, and an onboard charging system with a receptacle Compl. ¶¶157-161
U.S. Patent No. 10,604,023 - "Apparatus for energy transfer using converter and method of manufacturing same"
- Issued: March 31, 2020 Compl. ¶71
Technology Synopsis
The '023 patent details a vehicle power system architecture that utilizes switching devices (e.g., contactors) to selectively couple components '023 Patent, claim 1 '023 Patent, claim 17 The system includes an energy storage device, voltage converters, and an onboard charging system. The switching devices manage the electrical pathways, connecting the converters and energy storage device for different operational modes, such as driving or charging from an external source '023 Patent, abstract
Asserted Claims
At least independent claim 1 Compl. ¶172
Accused Features
The complaint alleges the accused vehicles' power systems infringe by using switching devices (contactors) to couple a voltage converter to the energy storage device and to couple the onboard charging system to the battery, alongside the other claimed components like the traction drive and charging receptacle Compl. ¶¶175-179
III. The Accused Instrumentality
Product Identification
- The complaint identifies the accused instrumentalities as "each Volvo-branded and Polestar-branded vehicle having electric or hybrid-electric powertrain systems," with the 2025 Volvo EX90 cited as a specific, non-limiting example Compl. ¶4, fn. 1 Compl. ¶86
Functionality and Market Context
- The complaint alleges that the accused vehicles incorporate sophisticated powertrain and charging systems that are core to their function and market position Compl. ¶29 These systems are alleged to include a high-voltage battery, a charging port that accepts energy from external sources, and onboard power electronics-including various converters and a control module-that manage the flow of energy to the battery Compl. ¶¶89-92 The complaint further alleges that Volvo and Polestar share key electric vehicle technologies, architectures (such as the SPA2 platform), and components, and that these vehicles are marketed and sold to U.S. consumers through an integrated sales channel Compl. ¶29 Compl. ¶88 An image in the complaint depicts a 2025 Volvo EX90 connected to a charging station, illustrating the accused functionality Compl. p. 32
IV. Analysis of Infringement Allegations
U.S. Patent No. 8,030,884 Infringement Allegations
| Claim Element (from Independent Claim 20) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a charge bus configured to receive charging energy from a voltage source; | The accused vehicles include a wire harness (charge bus) connected to a charging port, which is configured to receive energy from an external charger (voltage source). | ¶89 | col. 2:25-29 |
| an energy storage device configured to output a DC voltage and coupled to the charge bus; | The accused vehicles contain a high-voltage battery (energy storage device) that outputs DC voltage and is coupled to the wire harness. | ¶90 | col. 2:62-65 |
| a first bi-directional voltage modification assembly coupled to the charge bus; | The accused vehicles include a bi-directional converter (voltage modification assembly) that is coupled to the high-voltage cables (charge bus). | ¶91 | col. 2:14-16 |
| a controller configured to: monitor a transfer of the charging energy supplied to the energy storage device; compare the monitored transfer of charging energy with a threshold comprising one of a voltage of the energy storage device and an average rectified line voltage of the charge bus; and after the threshold has been crossed, control the first bi-directional voltage modification assembly to modify one of a voltage and a current of the charging energy supplied to the first energy storage device. | The accused vehicles possess a control module that monitors the energy transfer to the battery. When the battery's voltage reaches a threshold (e.g., full charge), the controller modifies the charging voltage and current to stop charging and prevent overcharging. | ¶92 | col. 2:32-39 |
- Identified Points of Contention:
- Scope Question: Claim 20 requires the "controller" to perform a specific three-step function: "monitor", "compare", and "control". The complaint alleges this is met when the vehicle's controller stops charging once the battery is full Compl. ¶92 A point of contention may arise over whether the accused controller's "full charge" detection and response constitutes the specific "comparison" with a "threshold" as recited in the claim, or if it uses a different, non-infringing control logic.
- Technical Question: A technical question for the court may be how the accused "control module" actually "modifies" the voltage and current. The complaint alleges this modification is to "stop charging the battery and prevent overcharging" Compl. ¶92 The infringement analysis will likely require evidence detailing the precise electrical behavior of the accused charging system to determine if its function aligns with the claimed modification step. The complaint includes a diagram from a technical paper to illustrate this alleged architecture Compl. p. 33
U.S. Patent No. 8,487,582 Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| an energy storage device configured to output a DC voltage; | The accused vehicles are equipped with a high-voltage battery (energy storage device) that outputs DC voltage. | ¶106 | col. 2:65-67 |
| a bi-directional voltage modification assembly coupled to the energy storage device; | The accused vehicles include a bi-directional converter (voltage modification assembly) that is coupled to the high-voltage battery. | ¶107 | col. 2:15-16 |
| a charge bus coupled to the energy storage device and to the bi-directional voltage modification assembly, the charge bus coupleable to a high-impedance voltage source; | The accused vehicles have a charge bus coupled to the battery and converter. The complaint alleges this bus is coupleable to a "high-impedance voltage source," such as a standard 120-volt, 12-amp electrical outlet. | ¶108 | col. 2:17-21 |
| a controller configured to: monitor a transfer of charging energy supplied from the high-impedance voltage source to the energy storage device; and modify one of a voltage and a current of the charging energy supplied to the energy storage device based on the monitored transfer of charging energy. | The accused vehicles contain a controller that monitors the energy transfer to the battery and modifies the voltage and current to manage the charge, for instance, by stopping the charge when a limit is reached or by implementing a smart schedule based on battery health. | ¶109; ¶51 | col. 2:28-35 |
- Identified Points of Contention:
- Scope Question: A critical issue will be the construction of the term "high-impedance voltage source". The complaint alleges this term reads on a "standard 120-volt, 12-amp electrical outlet" Compl. ¶108 The court will need to determine if the term, in the context of the patent, carries a specific technical meaning related to the impedance characteristics necessary for the claimed two-stage charging method, and whether a standard outlet meets that definition.
- Technical Question: Claim 1 requires the controller to modify charging parameters "based on the monitored transfer of charging energy". The complaint alleges the accused controller uses a "smart schedule" that considers "battery health, cheapest time and user preferences" Compl. p. 50 This raises the evidentiary question of whether this complex, multi-factor control strategy is the same as, or different from, the direct feedback loop described in the patent.
V. Key Claim Terms for Construction
For U.S. Patent No. 8,030,884:
- The Term: "bi-directional voltage modification assembly"
- Context and Importance: This term defines the central hardware component that the patent claims to repurpose for both driving and charging. Whether the accused "Hybrid Voltage Converter" (Compl. p. 36) meets this definition is fundamental to the infringement analysis. Practitioners may focus on this term to dispute the structural and functional correspondence between the claimed invention and the accused system.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The claim uses the general term "assembly", which may support a construction not limited to a single component. The specification describes the component as a "bi-directional DC-to-AC voltage inverter" ('884 Patent, col. 2:66-67), but the broader claim language could be argued to cover other types of bi-directional converters or systems of converters.
- Evidence for a Narrower Interpretation: The patent's figures and detailed description consistently depict the "assembly" as a three-phase inverter (14) used to drive a traction motor (40) ('884 Patent, FIG. 1; ʼ884 Patent, col. 3:10-15). This may support an argument that the term should be construed more narrowly as the specific type of inverter shown in the embodiments.
For U.S. Patent No. 8,487,582:
- The Term: "high-impedance voltage source"
- Context and Importance: The infringement theory for the '582 patent hinges on this term, which the complaint equates to a standard electrical outlet Compl. ¶108 The construction of this term will determine the universe of power sources to which the patent applies.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification provides the "utility grid" as an example of an external source '582 Patent, col. 3:49-56, which could be argued to encompass any standard grid connection, including a residential outlet. The term itself is not explicitly defined with limiting numerical values.
- Evidence for a Narrower Interpretation: The patent describes a "first stage" of charging that "allows for rapid charging that is limited primarily via the impedance of high-impedance voltage source 62" '582 Patent, col. 4:39-42 This functional language may support a narrower construction, suggesting the term implies a source with specific impedance characteristics that enable the claimed two-stage charging benefit, which a party could argue a standard outlet does not provide.
VI. Other Allegations
- Indirect Infringement: The complaint alleges that Defendants induce infringement of all asserted patents. The allegations state that Defendants knowingly and intentionally encourage infringement by providing user manuals, online instructional materials (including YouTube videos), marketing materials, and financial services that facilitate and instruct on the use of the accused charging features (e.g.,Compl. ¶93; Compl. ¶94).
- Willful Infringement: The complaint alleges willful infringement for all asserted patents based on both pre-suit and post-suit knowledge. The basis for pre-suit knowledge is alleged "detailed correspondence" from Plaintiff's agent to Defendants, which reportedly began in October 2025 and included the provision of claim charts in April 2026, followed by a telephonic conference in July 2026 Compl. ¶¶73-77 Compl. ¶94 Compl. ¶97
VII. Analyst's Conclusion: Key Questions for the Case
This case appears to center on the architecture of modern electric vehicle charging systems. The key questions for the court will likely involve both claim interpretation and a detailed technical comparison of the accused products to the patent claims.
A core issue will be one of definitional scope: can the term "high-impedance voltage source", as used in the '582 patent, be construed to cover a standard residential electrical outlet as the plaintiff alleges? The resolution of this claim construction dispute may be dispositive for the infringement allegations concerning that patent.
A second key question will be one of operational equivalence: do the accused vehicles' sophisticated "smart charging" systems-which allegedly optimize charging based on battery health and user preferences-perform the specific "monitor-compare-control" feedback loop recited in the '884 patent, or do they operate on a fundamentally different, non-infringing principle?
Finally, the detailed allegations of pre-suit notice, including the exchange of claim charts and subsequent discussions, raise a significant question regarding willfulness. The court will need to examine the extent of Defendants' knowledge of the patents and the objective reasonableness of their continued conduct after receiving notice, which will be critical for determining potential exposure to enhanced damages.