PTAB

IPR2015-01243

Snap-on Incorporated v. Milwaukee Electric Tool Corporation

Title: Lithium-Based Battery Pack for a High Current Draw, Hand Held Power Tool
Brief Description: The ’173 patent discloses a lithium-based battery pack for use with a handheld power tool. The invention is centered on a battery pack comprising a housing, a plurality of lithium-based battery cells, terminals for connecting to a power tool, and a locking mechanism, where the pack is capable of generating an average discharge current of 20 amps or more.

Prior Art Relied Upon: Sato (Japanese Publication No. JP 2002-110254) and Kanai (Application # 2003/0134189).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Sato taught a high-output lithium-ion secondary battery specifically developed for high-current applications like power tools, capable of delivering discharge currents well over 20 amps (e.g., 100A or 200A). Kanai was argued to disclose all structural aspects of the claimed battery pack, including a housing connectable to a handheld power tool (a rechargeable vacuum cleaner), a plurality of 18650-size lithium-ion cells, terminals, and a locking assembly.
- Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine the high-current battery cells of Sato with the battery pack structure of Kanai. The motivation stemmed from the known industry trend of improving power tool performance by using higher-discharge lithium-ion cells. Since both references disclosed the same standard 18650 cell geometry for power tool applications, substituting Sato’s improved cells into Kanai’s pack was presented as a simple and predictable design choice to achieve a known goal.
- Expectation of Success: A POSITA would have had a high expectation of success because the combination involved substituting known, identically-sized components (18650 cells) to achieve an improved, yet predictable, function (higher discharge current).

Prior Art Relied Upon: Fohr (European Patent Publication No. EP 1 266 725 A1), Sato (Japanese Publication No. JP 2002-110254), and Hallaj (Patent 6,468,689).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner asserted Fohr taught a complete battery pack system for a handheld power tool (a rechargeable screwdriver), including a housing that latches to the tool. Critically, Fohr explicitly disclosed that its battery pack could achieve a continuous current of 20 to 30 A. Sato was used, as in Ground 1, to supply the specific teachings of a high-current 18650 lithium-ion cell. Hallaj was cited for its general teachings on packaging a plurality of cells into a battery module, which Petitioner described as common knowledge.
- Motivation to Combine: A POSITA would have been motivated to use the specific high-current cells of Sato to implement the battery pack described in Fohr. Fohr provided the system-level design and performance goal (20-30A output), and Sato provided a known, off-the-shelf component (a high-current 18650 cell) to realize that goal. The combination was framed as implementing a disclosed system with known components.

Prior Art Relied Upon: Johnson (Application # 2004/0257038).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner’s argument rested on its contention that the ’173 patent was not entitled to an effective filing date earlier than December 9, 2008 (see Section 5 below). This would make Johnson, published in 2004, prior art under 35 U.S.C. §102(b). Petitioner argued that Johnson, which is an application in the ’173 patent’s priority chain, has a disclosure that is co-extensive with the ’173 patent specification. Therefore, by the Patent Owner's own admission during prosecution, Johnson provided full support for and thus anticipated claims 1-13.
Additional Grounds: Petitioner asserted an additional obviousness challenge against claims 1-5 and 7-13 based on Brotto (Patent 7,273,159) alone. Petitioner argued Brotto taught a complete Li-ion battery pack for handheld power tools capable of delivering over 20 amps.

"battery cells being capable of producing an average battery pack discharge current greater than or equal to approximately 20 amps": Petitioner argued that, under the broadest reasonable interpretation, this limitation is satisfied by cells that can produce ~20 amps during the intended intermittent use of a power tool. Petitioner contended this does not require a single, continuous discharge over the battery's entire rated capacity, a condition which would be inconsistent with typical power tool operation.
"hand held power tool": Petitioner adopted the construction from a related district court litigation: “a power tool that can be held in and supported by the operator’s hand or hands.” This broad construction was argued to encompass devices like the rechargeable vacuum cleaner disclosed in the Kanai reference.

Denial of Priority Date: The central technical pillar of the petition was the argument that the ’173 patent was not entitled to its claimed priority dates of November 22, 2002, or November 24, 2003. This argument was crucial for establishing Kanai, Fohr, Johnson, and Brotto as valid prior art references.
Lack of Enablement and Written Description: Petitioner contended that the priority applications failed the requirements of §112 because they did not contain sufficient written description or an enabling disclosure for the key limitation of "an average discharge current greater than or equal to approximately 20 amps." The petition argued that the priority documents merely stated this capability without teaching a POSITA how to achieve it, lacking crucial details on cell chemistry, electrode design, and other parameters necessary to practice the full, open-ended scope of the claim.

Petitioner requested institution of an inter partes review (IPR) and cancellation of claims 1-13 of Patent 7,944,173 as unpatentable.