DCT
1:20-cv-06389
Stored Energy Systems LLC v. Brunswick Corp
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Stored Energy Systems, LLC (Colorado)
- Defendant: Brunswick Corporation (Delaware) and Power Products, LLC (Delaware)
- Plaintiff’s Counsel: Fisherbroyles LLP
- Case Identification: 1:20-cv-06389, N.D. Ill., 10/28/2020
- Venue Allegations: Venue is alleged to be proper in the Northern District of Illinois because Defendant Brunswick Corporation has maintained its corporate headquarters and principal place of business in the district for over 110 years and because the alleged acts of infringement are committed in the district.
- Core Dispute: Plaintiff alleges that Defendants’ marine and industrial-grade battery chargers infringe a patent related to multi-stage battery charging methods designed to extend battery life.
- Technical Context: The technology concerns advanced battery charging regimes for mission-critical, standby batteries, such as those in emergency generators, aiming to improve reliability and lifespan by mitigating degradation caused by traditional continuous charging methods.
- Key Procedural History: The complaint alleges Defendants had pre-suit knowledge of the patent-in-suit via notice letters dated October 25, 2019, and December 27, 2019. Plaintiff asserts it has not licensed the patent. Subsequent to the filing of the complaint, the asserted patent underwent an ex parte re-examination, resulting in the issuance of a Re-examination Certificate that amended several claims, including the lead asserted independent claim, and cancelled another. The litigation will likely proceed based on the amended claims, which introduces new or clarified limitations that were not part of the patent when the complaint was filed.
Case Timeline
| Date | Event |
|---|---|
| 2013-11-07 | '125 Patent Priority Date |
| 2017-12-31 | Accused Products Launch (approx. late 2017) |
| 2018-04-17 | '125 Patent Issue Date |
| 2018-12-31 | Brunswick Acquires Power Products (approx. 2018) |
| 2019-10-25 | First Notice Letter of Alleged Infringement |
| 2019-12-27 | Second Notice Letter of Alleged Infringement |
| 2020-10-28 | Complaint Filing Date |
| 2022-03-30 | '125 Patent Re-examination Certificate Issued |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 9,948,125 - "Systems and Methods for Self-Contained Automatic Battery Charging and Battery-Life-Extension Charging," Issued April 17, 2018
The Invention Explained
- Problem Addressed: The patent addresses the problem that traditional continuous "float" charging, while mandated for standby batteries in applications like emergency generators, causes accelerated degradation of polyethylene separators in flooded lead-acid (SLI) batteries ('125 Patent, col. 2:10-21, col. 15:5-11). This premature failure can lead to short circuits and catastrophic, unexpected battery failure (Compl. ¶¶ 15-16).
- The Patented Solution: The invention is a multi-stage charging method that minimizes time spent at the damaging higher float voltage. It primarily uses a lower "eco-float" voltage, which is approximately the battery's open-circuit voltage, for the majority of the time (e.g., 90-99%) ('125 Patent, col. 17:15-24). The system employs monitoring and control circuitry to intelligently transition between various voltage modes (e.g., eco-float, float, refresh, boost) based on measured current draw and timed intervals, thereby extending battery life while ensuring it remains fully charged and ready for service ('125 Patent, col. 16:6-21; Fig. 11).
- Technical Importance: This approach seeks to fulfill regulatory mandates for continuous charging while mitigating the known life-reducing effects of that practice, thereby improving the reliability and longevity of mission-critical backup power systems (Compl. ¶ 17).
Key Claims at a Glance
- The complaint asserts infringement of at least independent claim 1 ('125 Patent, C1, col. 2:21-49; Compl. ¶ 28). The analysis below is based on the claim as amended by the Re-examination Certificate.
- Amended Independent Claim 1 requires:
- A monitoring component to measure DC output current delivered to a battery.
- A timing component.
- A charge control system that communicates with the monitoring and timing components, which is configured to:
- Obtain time and charge measurements.
- Determine a time and/or charge needed to complete a charge mode cycle to achieve a desired charge status.
- Transition between different DC output voltage settings based on the determined time/charge.
- The DC output voltage settings must include at least an "eco-float output voltage setting," a "refresh output voltage setting," and a "boost output voltage setting."
- The "eco-float output voltage setting" is further defined as comprising a voltage "equal to or nominally higher than an open-circuit voltage of the battery."
- The complaint reserves the right to assert additional claims (Compl. ¶ 29).
III. The Accused Instrumentality
- Product Identification: The Guest™, ChargePro™, Marinco™, and ProMariner™ brands of battery charging systems (the "Accused Instrumentalities") (Compl. ¶ 27).
- Functionality and Market Context: The Accused Instrumentalities are described as "on-board marine and industrial-grade battery chargers" (Compl. ¶ 24). The complaint alleges they incorporate "leading advancements in digital charging technology," including "[m]icroprocessor and software control for precision, fully automatic 5-stage performance charging," "[i]ndividual battery sensing and control," and an "[a]uto-maintain energy saver mode" (Compl. ¶¶ 24-25). These products were allegedly launched in late 2017 or early 2018 and are sold through Defendant Brunswick's nationwide distribution channels (Compl. ¶¶ 7, 24).
IV. Analysis of Infringement Allegations
The complaint’s infringement allegations are narrative and largely track the language of the original patent claims (Compl. ¶ 28). No probative visual evidence provided in complaint.
'125 Patent Infringement Allegations
| Claim Element (from Amended Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a monitoring component configured to measure a direct current (DC) output current delivered by the charging system to a battery... | The Accused Instrumentalities comprise "a monitoring component configured to measure a direct current output current delivered to a battery, wherein the output current is a function of an existing charge status of the battery." | ¶28 | col. 17:49-54 |
| a timing component | The Accused Instrumentalities comprise "a timing component." | ¶28 | col. 17:54-55 |
| a charge control system...configured for: obtaining at least one of a time measurement...and a charge measurement... | The Accused Instrumentalities are configured for "obtaining at least one of a time measurement from the timing component and a charge measurement from the monitoring component." | ¶28 | col. 17:55-59 |
| ...based on the measurement, determining at least one of a time to complete the charge mode cycle and a charge to complete a charge mode cycle... | The Accused Instrumentalities are configured for "based on the measurement, determining at least one of a time to complete the charge mode cycle and a charge to complete a charge mode cycle to achieve a desired charge status of the battery." | ¶28 | col. 17:59-63 |
| ...based on at least one of the determined time and the determined charge...transitioning to a select one of a number of DC output voltage settings... | The Accused Instrumentalities are configured for "based on at least one of the determined time and the determined charge...transitioning to a select one of a number of DC output voltage settings..." | ¶28 | col. 17:63-67 |
| ...wherein the DC output voltage settings include at least an eco-float output voltage setting, a refresh output voltage setting, and a boost output voltage setting. | The Accused Instrumentalities "provide one or more DC output voltage settings, including one or more of an eco-float output voltage setting, a refresh output voltage setting, and a boost output voltage setting." | ¶28 | col. 18:1-3 |
| ...wherein the eco-float output voltage setting comprises a voltage equal to or nominally higher than an open-circuit voltage of the battery. | The complaint alleges the accused products have an "eco-float output voltage setting" and an "auto-maintain energy saver mode." It does not provide sufficient detail for analysis of whether these features meet the specific voltage level required by this limitation, which was added during re-examination. | ¶¶25, 28 | col. 17:15-18 |
- Identified Points of Contention:
- Scope Questions: A central question will be whether the accused products' "auto-maintain energy saver mode" (Compl. ¶ 25) falls within the scope of the claim term "eco-float output voltage setting," particularly as that term is now narrowly defined in the amended claim to require a voltage "equal to or nominally higher than an open-circuit voltage of the battery" ('125 C1 Patent, cl. 1). The complaint, filed prior to the re-examination, does not contain factual allegations specific to this voltage level.
- Technical Questions: The complaint's allegations that the accused products "determin[e]" a time and charge to complete a cycle are conclusory (Compl. ¶ 28). A key technical question will be what evidence demonstrates that the accused products' software performs a dynamic calculation based on live measurements, as the claim language suggests, rather than merely executing a static, pre-programmed sequence of timed states.
V. Key Claim Terms for Construction
The Term: "eco-float output voltage setting"
- Context and Importance: This term is critical because it was a basis for the claim's patentability over prior art, as evidenced by its addition during re-examination. The infringement analysis for the amended claim will turn on whether the accused products have a mode that meets this specific definition.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: A party might argue that without an explicit definition in the specification, the term should be given a broad, plain meaning encompassing any energy-saving or low-power mode.
- Evidence for a Narrower Interpretation: The amended claim itself provides a clear functional definition: a setting that "comprises a voltage equal to or nominally higher than an open-circuit voltage of the battery" ('125 C1 Patent, cl. 1). The specification provides strong corroboration, describing the eco-float voltage in identical terms ('125 Patent, col. 17:15-18), which may suggest this narrow construction was intended by the patentee.
The Term: "determining"
- Context and Importance: Practitioners may focus on this term because it implies an active, intelligent process. The dispute may hinge on whether the accused devices' operation involves a dynamic calculation based on inputs, or simply follows a fixed, predetermined logic that does not constitute "determining" in the claimed sense.
- Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: A party could argue that "determining" can encompass retrieving a value from a look-up table based on an input, not just a complex real-time calculation.
- Evidence for a Narrower Interpretation: The claim requires "determining...based on the at least one of the time measurement and the charge measurement" ('125 C1 Patent, cl. 1). This language may support an interpretation that requires an active computation using live data as inputs, as opposed to executing a static, pre-set routine.
VI. Other Allegations
- Indirect Infringement: The complaint alleges inducement by "actively instructing, assisting, and encouraging others" to use the accused products in an infringing manner (Compl. ¶ 33). It also pleads contributory infringement, alleging the products are a material part of the invention, are especially made for infringing use, and are not staple articles of commerce with substantial non-infringing uses (Compl. ¶¶ 34, 40).
- Willful Infringement: Willfulness is alleged based on Defendants’ purported pre-suit knowledge of the '125 Patent, citing notice letters sent on October 25, 2019, and December 27, 2019, and their subsequent continued sale of the Accused Instrumentalities (Compl. ¶ 31).
VII. Analyst’s Conclusion: Key Questions for the Case
- A central issue will be one of proof and procedure: given that the asserted claim was narrowed during a re-examination that concluded after the complaint was filed, can the Plaintiff provide sufficient factual evidence to prove that the accused products meet the newly-added limitation defining the specific voltage level of the "eco-float output voltage setting"?
- A key evidentiary question will be one of technical operation: does the accused products' "microprocessor and software control" (Compl. ¶ 24) perform the active, input-based step of "determining" a time and charge for a cycle, as required by the claim, or does it operate on a fixed, pre-programmed schedule that may not meet this claim requirement?