DCT

5:24-cv-00133

LithiumHub LLC v. Shenzhen Fbtech Electronics Ltd

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I. Executive Summary and Procedural Information

  • Parties & Counsel:
  • Case Identification: 5:24-cv-00133, E.D. Tex., 09/13/2024
  • Venue Allegations: Venue is asserted on the basis that the defendant is a foreign corporation not resident in the United States and may therefore be sued in any judicial district.
  • Core Dispute: Plaintiff alleges that Defendant’s "Dakota Lithium" brand of Lithium-Ion batteries infringes patents related to control circuits that provide fault detection and protection.
  • Technical Context: The technology concerns solid-state switching circuits within battery management systems designed to protect lithium-ion batteries from damaging conditions such as over-charging, over-discharging, and short circuits.
  • Key Procedural History: The complaint alleges that Defendant was put on notice of the asserted patents and its alleged infringement through an International Trade Commission (ITC) complaint filed on September 12, 2024, one day prior to the filing of this district court action. The complaint also notes that the inventor, Martin Koebler, reacquired the asserted patents in a 2020 bankruptcy sale of his former company, StarkPower, Inc.

Case Timeline

Date Event
2010-11-29 Priority Date for U.S. Patent Nos. 9,412,994 and 9,954,207
2016-08-09 U.S. Patent No. 9,412,994 Issued
2018-04-24 U.S. Patent No. 9,954,207 Issued
2024-09-12 Related ITC Complaint Filed Against Defendant
2024-09-13 Complaint Filed in E.D. Tex.

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 9,412,994 - "Lithium Starter Battery and Solid State Switch Therefor," issued August 9, 2016

The Invention Explained

  • Problem Addressed: The patent describes the limitations of traditional lead-acid starter batteries, noting they are heavy, bulky, inefficient, and perform poorly in cold weather (Compl. ¶1; ’994 Patent, col. 1:26-34). It further identifies the shortcomings of conventional protection circuits, such as mechanical relays, which consume power, are not directionally controllable, and can "weld" shut, creating a safety issue (’994 Patent, col. 2:15-29).
  • The Patented Solution: The invention proposes a lithium-ion battery pack that incorporates a unique solid-state switch configuration to protect the battery cells (’994 Patent, Abstract). Instead of a simple on/off switch, the patent describes using pairs of solid-state switches (e.g., MOSFETs) where their "Sources" or "Drains" are electrically connected. This configuration allows a controller to independently manage the flow of current for charging and discharging, thereby preventing conditions like over-voltage or under-voltage without completely disabling the battery (’994 Patent, col. 2:36-56; col. 9:1-19).
  • Technical Importance: This design allows for the creation of lighter, more reliable, and longer-lasting lithium-ion starter batteries that can directly replace lead-acid batteries in existing vehicles without modification, while offering superior protection and performance (’994 Patent, col. 4:36-50).

Key Claims at a Glance

  • The complaint asserts independent claims 1 and 14 (Compl. ¶33).
  • Independent Claim 1 requires: a battery pack with a housing, at least one lithium-based cell, and a circuit board. The circuit board must be configured to (a) "balance each individual cell," (b) have a "cutoff function," and (c) include a specific "plurality of pairs of solid state switches" where the drains or sources within a pair are connected.
  • Independent Claim 14 is similar but only requires the circuit board to have a "cutoff function" and the specific switch configuration; it does not explicitly require the "balance" function.
  • The complaint reserves the right to assert additional claims (Compl. ¶33).

U.S. Patent No. 9,954,207 - "Lithium Battery with Solid State Switch," issued April 24, 2018

The Invention Explained

  • Problem Addressed: The patent addresses the same problems as the ’994 Patent, citing the disadvantages of lead-acid batteries and conventional relay-based protection circuits for high-power applications (’207 Patent, col. 1:30-40).
  • The Patented Solution: The invention is a lithium battery, for use as either a starter battery or a deep cycle battery, that includes the solid-state switching configuration for protection against over-charging, over-discharging, and short circuits (’207 Patent, Abstract). The core of the solution is the same unique arrangement of paired solid-state switches with interconnected drains or sources, enabling bidirectional current control (’207 Patent, col. 2:39-60). The patent explicitly notes the invention is also useful as a "Deep Cycle battery" (’207 Patent, Abstract).
  • Technical Importance: The technology provides a robust, efficient, and lightweight power source for demanding applications, extending beyond engine starting to include deep cycle uses like in boats, RVs, or solar systems (’207 Patent, col. 5:1-5).

Key Claims at a Glance

  • The complaint asserts independent claims 1 and 12 (Compl. ¶56).
  • Independent Claim 1 is directed to a "battery pack...for powering an electric motor for starting an internal combustion engine" and requires a housing, a lithium cell, and the specific "solid state switching apparatus" with the parallel-pair, drain/source-connected configuration.
  • Independent Claim 12 is directed to a "deep cycle battery" and requires a housing, a lithium cell, a "battery management system" that protects against various faults (overvoltage, undervoltage, etc.), and specifies that the BMS circuit board must comprise the same solid-state switching apparatus as claimed in Claim 1.
  • The complaint reserves the right to assert additional claims (Compl. ¶56-57).

III. The Accused Instrumentality

Product Identification

  • The complaint accuses Lithium-Ion batteries sold under the brand name "Dakota Lithium" (Compl. ¶23). A long list of specific models is provided, and the "Dakota Lithium 12V 100AH Deep Cycle LiFePo4 Battery" is identified as a representative product (Compl. ¶26, ¶33, ¶56). A screenshot from the defendant's website shows the representative product (Compl. p. 8).

Functionality and Market Context

  • The accused products are lithium-iron-phosphate (LiFePO4) deep cycle batteries marketed for applications including "home solar, electric vehicles & more" (Compl. p. 8). The complaint alleges these products are manufactured by the Defendant and sold in the United States through various channels, including the defendant’s website, its Amazon store, and a network of retail partners (Compl. ¶25, ¶28). A screenshot of the defendant's dealer locator page shows retailers in states including Texas and Virginia (Compl. p. 9). The complaint alleges that the accused products contain a "Built in BMS" (Battery Management System) that performs the infringing functions (Compl. ¶26).

IV. Analysis of Infringement Allegations

The complaint references claim chart exhibits (Exh. D for the ’994 Patent, Exh. E for the ’207 Patent) that were not included with the filed complaint (Compl. ¶33, ¶56). The following analysis summarizes the infringement theory based on the narrative allegations in the complaint body.

’994 Patent Infringement Allegations

The complaint alleges that the accused "Dakota Lithium" products, as represented by the 12V 100AH model, contain all elements of at least claims 1 and 14 (Compl. ¶33). The core of the infringement theory appears to be that the "Built in BMS" of the accused products constitutes the claimed "circuit board" (Compl. ¶26). This BMS is alleged to perform the required "cutoff function" and to contain the patented solid-state switch architecture—a "plurality of pairs of solid state switches" with their drains or sources connected in the claimed parallel configuration (Compl. ¶¶36-39). For Claim 1, the BMS is also alleged to perform the "balance" function for the individual lithium cells (Compl. ¶35). Visual evidence from the defendant's website, such as a product page for the representative battery, is used to support the existence of the accused products and their general features (Compl. p. 8).

’207 Patent Infringement Allegations

The infringement theory for the ’207 Patent is substantially similar, alleging that the BMS within the accused "Dakota Lithium" batteries embodies the claimed "solid state switching apparatus" (Compl. ¶¶59-62). The complaint specifically targets the deep cycle nature of the accused products, which aligns with the preamble of asserted Claim 12 ("A deep cycle battery") (Compl. ¶64). The product description for the representative battery states it is "Ideal for deep cycle applications like trolling motors, solar energy storage, or boating" (Compl. p. 8). The complaint alleges that this BMS provides the protective functions recited in Claim 12 and contains the specific parallel-pair switch architecture at the heart of the patent (Compl. ¶¶65-71).

V. Key Claim Terms for Construction

  • The Term: "a circuit board ... configured to balance each individual cell" (’994 Patent, Claim 1)

    • Context and Importance: This term is critical because it is a distinguishing feature of Claim 1 relative to Claim 14 of the ’994 Patent. The defendant may argue its BMS provides safety cutoffs but does not perform "balancing" as required by the claim, thereby creating a non-infringement argument for Claim 1.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The specification defines balancing simply as "the process of forcing all of the cells to have identical voltages" (’994 Patent, col. 7:25-28). A plaintiff could argue that any circuit function that tends to equalize cell voltages meets this definition.
      • Evidence for a Narrower Interpretation: The patent depicts a "balancing circuit board" and a controller (Fig. 7) separately from a simple cutoff switch, suggesting "balancing" is an affirmative function distinct from merely preventing over/under voltage (’994 Patent, Fig. 7-8). A defendant could argue this implies a requirement for a specific, active balancing circuit, not just protective cutoffs.

  • The Term: "solid state switching apparatus" comprising "a plurality of pairs of solid state switches" with drains/sources connected (’207 Patent, Claims 1 and 12)

    • Context and Importance: Practitioners may focus on this term because it recites the core structural invention. The central technical dispute will likely be whether the defendant's BMS circuit contains this specific architecture, as opposed to a different, more conventional arrangement of protective switches.
    • Intrinsic Evidence for Interpretation:
      • Evidence for a Broader Interpretation: The patent describes the function of this apparatus as allowing independent, bidirectional control of charge and discharge currents (’207 Patent, col. 9:36-53). A plaintiff may argue that any structure performing this specific function falls within the scope.
      • Evidence for a Narrower Interpretation: The claims recite a highly specific electrical topology: pairs of switches connected in parallel, with the sources or drains within each pair tied together (’207 Patent, col. 13:42-52). The specification provides detailed schematics (e.g., Figs. 16-23) illustrating this exact configuration. A defendant will likely argue that these embodiments strictly define the claim scope and that its BMS uses a different, non-infringing circuit design.

VI. Other Allegations

  • Indirect Infringement: The complaint alleges inducement to infringe under 35 U.S.C. § 271(b). The factual basis asserted is that Defendant manufactures the accused products for the U.S. market, promotes them for sale, and actively encourages direct infringement by third parties (importers, retailers, and end-users) by, for example, directing customers to a U.S. dealer network (Compl. ¶¶27-28, 32, 55).
  • Willful Infringement: Willfulness is alleged based on Defendant having "actual knowledge" of the asserted patents and their infringement "from at least the filing of the ITC Complaint" on September 12, 2024 (Compl. ¶50, ¶73). This frames the willfulness claim as being based on alleged post-suit knowledge (counting from the ITC action).

VII. Analyst’s Conclusion: Key Questions for the Case

  1. A central evidentiary question will be one of technical structure: Does the internal Battery Management System (BMS) of the accused "Dakota Lithium" products incorporate the specific "solid state switching apparatus" claimed in the patents—namely, an architecture of paired, parallel solid-state switches with their sources or drains electrically tied together? The outcome may depend heavily on reverse engineering and discovery of the defendant's circuit designs.
  2. The case may also turn on a question of definitional scope: For U.S. Patent No. 9,412,994, what is the proper construction of "configured to balance each individual cell"? Whether the accused BMS performs a function that meets this definition, as opposed to only a simpler voltage cutoff function, will be critical to the infringement analysis of Claim 1.
  3. A third key issue will be one of proof of conduct: For the indirect and willful infringement claims, can the Plaintiff establish that the Defendant, a foreign manufacturer, possessed the requisite knowledge and specific intent to encourage infringement in the U.S., particularly based on notice from the parallel ITC proceeding?