DCT
3:25-cv-00403
Power Probe Group Inc v. KMC Electronics LLC
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Power Probe Group, Inc. (Delaware)
- Defendant: KMC Electronics LLC (North Carolina)
- Plaintiff’s Counsel: Shumaker, Loop & Kendrick, LLP
- Case Identification: 3:25-cv-00403, W.D.N.C., 06/12/2025
- Venue Allegations: Plaintiff alleges venue is proper in the Western District of North Carolina because its principal place of business is located there, and Defendant directed its patent licensing and enforcement efforts into the district.
- Core Dispute: Plaintiff seeks a declaratory judgment that its automotive diagnostic products do not infringe Defendant's patent and/or that the patent is invalid, and further alleges that Defendant's enforcement attempts violate North Carolina's Abusive Patent Assertion Act.
- Technical Context: The technology involves electronic handheld testers used by automotive technicians to diagnose parasitic electrical drains by measuring the voltage drop across a fuse without removing it from the circuit.
- Key Procedural History: The complaint states that prior to the lawsuit, Defendant sent demand letters to Plaintiff accusing its products of infringement. A central dispute raised in the complaint concerns the patent's effective priority date; Plaintiff alleges that key claim limitations were not disclosed in the 2013 provisional application, which if true would push the priority date to 2014 and expose the patent to invalidity challenges from prior art that was on sale in 2012.
Case Timeline
| Date | Event |
|---|---|
| 2012 (late) | MATCO TH209 Device allegedly launched and placed "on sale" |
| 2013-05-20 | Provisional Application No. 61/855,654 filed |
| 2014-05-07 | Non-Provisional Application No. 14/271,542 filed |
| 2016-11-15 | U.S. Patent No. 9,494,634 issues |
| 2025-03-06 | Defendant sends first demand letter to Plaintiff |
| 2025-03-25 | Defendant sends second demand letter to Plaintiff |
| 2025-06-12 | Complaint for Declaratory Judgment filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 9,494,634 - "Current Tester" (November 15, 2016)
The Invention Explained
- Problem Addressed: The patent's background section identifies that conventional methods for detecting parasitic current leaks in automotive circuits are difficult and time-consuming, as they require removing a fuse and connecting an ammeter in series, often in a cramped fuse panel (Compl. ¶27; ’634 Patent, col. 1:18-37).
- The Patented Solution: The invention is a handheld device that solves this problem by measuring the small voltage drop directly across the contacts of an installed fuse. A computing device within the tester then uses a "pre-determined voltage drop/current relationship" specific to the component (e.g., the fuse type) to calculate the corresponding current flow and display it to the user, eliminating the need to break the circuit (’634 Patent, Abstract; col. 2:51-63).
- Technical Importance: This method offers a significantly more convenient and rapid way for technicians to diagnose parasitic current drains, which are a common source of vehicle battery failure (’634 Patent, col. 1:33-37).
Key Claims at a Glance
- The complaint focuses on the independent apparatus claim, Claim 1 (Compl. ¶32). Defendant's pre-suit correspondence allegedly accused "the independent apparatus and method claims" of infringement (Compl. ¶80).
- Essential elements of Independent Claim 1 include:
- A current tester for parasitic current leaks comprising a probe;
- A computing device for converting a voltage drop across a fuse to a current;
- An input device for selecting among multiple fuse types;
- Each fuse type having a pre-determined voltage drop/current relationship stored in the computing device; and
- An output device for signaling a presence or non-presence of the parasitic current leak.
III. The Accused Instrumentality
Product Identification
- The complaint identifies the "DM300AUTO Digital Multimeter" and the "Fuse Monitor" as the Accused Products (Compl. ¶2).
Functionality and Market Context
- The complaint alleges that Defendant’s infringement accusations center on specific features of the Accused Products. For the DM300AUTO, the feature is its "Parasitic Draw Diagnostic Mode," which enables "fuse voltage drop testing" (Compl. ¶71). An image from the product's marketing materials highlights this capability (Compl. Ex. H, p. 21).
- For the Fuse Monitor, the relevant functionality is its advertised ability to "quickly locate parasitic draw in vehicles without fuse removal" (Compl. ¶73). A marketing graphic for the Fuse Monitor shows its intended use for troubleshooting car fuses and battery drains (Compl. Ex. I, p. 22).
- Plaintiff positions the Accused Products as innovative and high-quality diagnostic tools for the automotive industry (Compl. ¶75).
IV. Analysis of Infringement Allegations
The complaint states that Defendant did not provide a claim chart with its demand letters (Compl. ¶¶83, 101). The infringement theory presented here is therefore based on Plaintiff's description of Defendant's allegations and the functionality of the Accused Products as described in the complaint.
’634 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a probe, | The accused multimeter and fuse monitor products are supplied with and use electrical test leads or probes to make contact with the circuit. | ¶¶70, 72 (Exs. H, I) | col. 2:12-13 |
| a computing device for converting a voltage drop across a fuse to a current, the voltage drop is associated with the parasitic current leak... | The DM300AUTO has a "Parasitic Draw Diagnostic Mode" for "fuse voltage drop testing," and the Fuse Monitor is used to "locate parasitic draw," which implies the conversion of a measured voltage drop to a current value. | ¶¶71, 73 | col. 2:26-31 |
| an input device for selecting among multiple fuses types... | The complaint does not specify what feature of the Accused Products is alleged to meet this limitation. The complaint does, however, highlight that the MATCO TH209 prior art device includes a "Fuse Value button" for selecting a fuse rating. | ¶65 | col. 4:5-7 |
| ...each fuse type having a pre-determined voltage drop/current relationship stored in said computing device, | The complaint alleges that Defendant has failed to explain "if or how either device stores a pre-determined voltage drop/current relationship." | ¶102 | col. 4:5-14 |
| an output device for signaling a presence or non-presence of the parasitic current leak... | Both Accused Products include digital displays that provide a visual output of the test results to the user. | ¶¶70, 72 (Exs. H, I) | col. 2:17-18 |
Identified Points of Contention
- Factual Question: A primary factual dispute may concern whether the Accused Products actually contain and use "a pre-determined voltage drop/current relationship stored in said computing device" for different fuse types, as required by the claim. The complaint suggests this is a point of contention by noting Defendant's failure to provide specifics on this element (Compl. ¶102).
- Priority Date and Validity: The most significant dispute raised in the complaint is not over infringement, but over validity, hinging on the patent's effective filing date. Plaintiff argues that the "pre-determined voltage drop/current relationship" limitation lacks written description support in the 2013 provisional application (Compl. ¶¶50-51). If the court agrees, the patent's priority date would be 2014, potentially rendering it invalid under the on-sale bar due to the MATCO TH209 device, which was allegedly "on sale" in late 2012 (Compl. ¶¶52, 57). The complaint includes an annotated image of this prior art device, mapping its features to the patent's claim limitations (Compl. ¶67, p. 20).
V. Key Claim Terms for Construction
1. "pre-determined voltage drop/current relationship"
- Context and Importance: This term is central to the invention and is the focal point of Plaintiff's argument that the patent is not entitled to its claimed 2013 priority date (Compl. ¶¶37, 50). The construction of this term will be critical for assessing both written description support in the provisional application (a validity issue) and whether the accused products practice this limitation (an infringement issue).
- Intrinsic Evidence for a Broader Interpretation: The specification suggests this "relationship" can be a "mathematical equation (for example, by regression analysis) or defined in a look-up table," which may support a more flexible interpretation not strictly tied to empirical data points (’634 Patent, col. 2:60-63).
- Intrinsic Evidence for a Narrower Interpretation: The patent’s detailed description and figures illustrate the concept using specific graphs of amperage versus voltage drop derived for a "5 amp mini fuse" (’634 Patent, col. 2:64-65; Figs. 3 & 4). This could support an argument that the term requires specific, empirically-derived data sets corresponding to discrete fuse types.
2. "input device for selecting among multiple fuses types"
- Context and Importance: This term is linked to the "pre-determined relationship" and is critical to the invalidity analysis. Plaintiff alleges that the prior art MATCO TH209 device had a "Fuse Value button" that allowed a user to select a fuse rating from 5A to 80A (Compl. ¶65). The court's interpretation will determine whether selecting an amperage constitutes selecting a "fuse type" as claimed.
- Intrinsic Evidence for a Broader Interpretation: The specification lists "amperage rating" as a parameter for identifying a component like a fuse, which could support an argument that selecting an amperage is equivalent to selecting a "fuse type" (’634 Patent, col. 3:49-51).
- Intrinsic Evidence for a Narrower Interpretation: The specification also lists distinct fuse styles like "low-profile mini, mini, ATO or maxi" as examples of fuse types (’634 Patent, col. 3:49-50). This could support a narrower construction requiring selection based on a physical fuse standard, not merely its amperage rating.
VI. Other Allegations
North Carolina Abusive Patent Assertion Act (APAA) Violation
- The complaint alleges that Defendant’s pre-suit conduct constitutes a bad-faith assertion of patent infringement in violation of the APAA (Compl. ¶¶132-137). The allegations are based on factors enumerated in the statute, including:
- Sending a demand letter with an "unreasonably short period of time" for response ("immediately") (Compl. ¶¶103-104).
- Failing to conduct an adequate pre-suit infringement analysis, as evidenced by the lack of a claim chart or specific details on how key limitations are met (Compl. ¶¶99-102).
- Seeking an injunction, which Plaintiff argues is "objectively unreasonable" for a non-practicing entity to obtain (Compl. ¶¶114-115).
Indirect Infringement
- Plaintiff seeks a declaratory judgment of non-infringement for all forms of infringement, including indirect infringement (Compl. ¶120). The complaint does not detail a specific theory of indirect infringement but notes Defendant's threats are directed at products sold by Plaintiff (Compl. ¶76).
VII. Analyst’s Conclusion: Key Questions for the Case
- A core issue will be one of priority and validity: The case appears to hinge on whether the '634 patent is entitled to the 2013 filing date of its provisional application. This question turns on whether the provisional specification provides adequate written description for the "pre-determined voltage drop/current relationship" limitation. The answer will determine if the 2012 MATCO TH209 device qualifies as invalidating prior art under the on-sale bar.
- A key evidentiary question will be one of factual infringement: Assuming the patent survives the validity challenge, the focus will shift to whether Plaintiff's DM300AUTO and Fuse Monitor products actually implement the specific claimed method of storing and selecting from pre-determined voltage/current relationships for multiple, distinct fuse types.
- A dispositive question will be one of statutory conduct: Independently of the patent-specific issues, the court will need to rule on whether Defendant's pre-suit demand letters and licensing conduct meet the standard for a "bad-faith assertion of patent infringement" under the North Carolina statute, which could result in an award of fees and other remedies.