PTAB

IPR2015-00595

Chervon North America Inc v. Milwaukee Electric Tool Corp

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Lithium-Based Battery Pack for a High Current Draw, Hand-Held Power Tool
  • Brief Description: The ’173 patent describes a rechargeable battery pack for high-current, hand-held power tools. The invention uses a plurality of lithium-based chemistry cells within a housing that connects to the power tool, capable of producing a high average discharge current.

3. Grounds for Unpatentability

Ground 1: Obviousness over Kasahara, Linden, and Anthony - Claims 1-13 are obvious over [Kasahara](https://ai-lab.exparte.com/case/ptab/IPR2015-00595/doc/1007) in combination with [Linden](https://ai-lab.exparte.com/case/ptab/IPR2015-00595/doc/1012) and further in view of [Anthony](https://ai-lab.exparte.com/case/ptab/IPR2015-00595/doc/1009).

  • Prior Art Relied Upon: Kasahara (WO 02/03484), Linden (The Handbook of Batteries, 3rd Ed., 2001), and Anthony (Patent 5,213,913).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Kasahara taught the core elements of a rechargeable, lithium-based battery pack for power tools, including a housing, multiple cells, and terminals. However, Kasahara did not explicitly disclose cells capable of meeting the claimed discharge current of approximately 20 amps or a specific locking mechanism. Petitioner asserted that Linden, a well-known battery handbook, remedied this deficiency by disclosing commercially available lithium cobalt oxide 26650 cells with the precise size and discharge characteristics (10 amps per cell) that, when combined in parallel, would achieve the 20-amp limitation. To address the final limitation of a locking assembly, Petitioner contended that Anthony taught an improved, resiliently biased latching arrangement specifically for removably securing a battery pack to a hand-held power tool.
    • Motivation to Combine: A POSITA would combine Kasahara and Linden because Kasahara generally taught using lithium cells for power tools, and Linden provided known, predictable, and commercially available high-discharge cells suitable for such a high-current application, thereby solving a design need. The motivation to add Anthony was driven by the clear design requirement for a removable battery pack, as shown in Kasahara, to be securely attached to a power tool. Anthony provided a known and logical solution for this exact problem, enhancing the portability and convenience of a cordless tool.
    • Expectation of Success: A POSITA would have a high expectation of success, as the combination involved arranging known elements (a battery pack, high-current cells, a latch) each performing its known function to yield a predictable result.

Ground 2: Obviousness over Yamaki and Anthony - Claims 1-8 and 10-13 are obvious over [Yamaki](https://ai-lab.exparte.com/case/ptab/IPR2015-00595/doc/1011) in combination with Anthony.

  • Prior Art Relied Upon: Yamaki (Application # 2002/0168568) and Anthony (Patent 5,213,913).

  • Core Argument for this Ground:

    • Prior Art Mapping: Petitioner argued that Yamaki, like Kasahara, taught a lithium-ion battery pack for "portable electromotive tools." Yamaki provided detailed instructions on how to construct battery cells with specific lithium-based chemistries and disclosed a battery module with cells in a resin container, control circuitry, and terminals. Petitioner asserted that Yamaki’s disclosed 1.2 Ah cells, when arranged in a common parallel configuration (e.g., four cells), would achieve a discharge current of 19.2 amps, meeting the claimed ~20 amp limitation. As Yamaki did not explicitly describe a locking mechanism for its pack, Petitioner again relied on Anthony to supply this element, arguing its latching arrangement was a known solution for attaching battery packs to power tools.
    • Motivation to Combine: The motivation was based on complementing known technologies. Yamaki expressly taught using its battery pack as a power source for portable tools, and Anthony taught a known battery pack with a locking assembly for use with such tools. A POSITA seeking to implement Yamaki’s battery in a hand-held tool would have recognized the need for a secure, removable attachment and been naturally guided to a known solution like that in Anthony to improve usability and convenience. Industry trends toward high-power cordless tools would further motivate this combination.
    • Expectation of Success: A POSITA would expect success because combining Yamaki's detailed battery cell teachings with Anthony's well-understood mechanical latch involved the application of known technologies for their intended purposes with predictable results.

  • Additional Grounds: Petitioner asserted an additional obviousness challenge for claim 9 based on Yamaki in combination with Anthony and further in view of Staarman (Patent 5,179,337). This ground relied on the same core combination as Ground 2 but added Staarman to explicitly teach a protection circuit for preventing overdischarge in rechargeable lithium batteries used in portable tools.

4. Key Claim Construction Positions

  • "battery cells being capable of producing an average battery pack discharge current greater than or equal to approximately 20 amps": Petitioner dedicated significant argument to this term, contending it is indefinite under §112 because the patent fails to specify the conditions for measurement, such as the time period or application. For the purposes of the IPR, Petitioner proceeded under a broad interpretation where the limitation is met by cells capable of producing ~20 amps when used with a power tool for an application consistent with its intended use.
  • "nominal voltage": Petitioner argued this term, recited in claims 5, 7, and 11, is also indefinite. The specification provides conflicting examples (3.6 V, 4 V, 4.2 V), and the prosecution history suggests it could mean the voltage of a fully charged cell, contrary to its ordinary meaning as a midpoint voltage. Petitioner assumed any of these interpretations could apply for its obviousness analysis.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-13 of the ’173 patent as unpatentable.