Battery Pack Systems
Job Description
Battery / Pack Systems Engineer – Integrated Rack Power Platform
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Location: San Jose, CA (On-site)
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Reports To: Head of Engineering, Data Center Power Platform
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About the Role
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We are building an integrated PSU + BBU rack power shelf that combines power conversion and solid-state battery backup into a single high-density platform for hyperscale AI data centers.
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This product replaces traditional separate PSU and BBU shelves with a unified architecture that leverages the unique safety and performance characteristics of solid-state battery cells.
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As the Battery / Pack Systems Engineer, you will own everything from cell to pack—including mechanical integration, Battery Management System (BMS) architecture, thermal management of the battery section, charge/discharge optimization, safety engineering, and cycle life validation. You will serve as the critical bridge between our cell technology and the power platform, translating evolving cell-level specifications into robust pack-level designs in near real-time.
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What You'll Do
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Design the complete cell-to-pack mechanical assembly, including:
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Cell stacking
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Compression systems
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Electrical interconnects (wire bonding, busbar welding, or flex circuits)
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Structural integration within the shared PSU + BBU enclosure
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Architect the Battery Management System (BMS) hardware topology, including:
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Distributed versus centralized sensing
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Passive versus active balancing
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Protection FET sizing
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Sense line routing
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Communication interfaces
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Develop and tune State-of-Charge (SOC) and State-of-Health (SOH) estimation algorithms using:
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Coulomb counting
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Extended Kalman filtering
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Impedance-based estimation methods
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Solid-state battery electrochemistry models
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Co-develop charge and discharge profiles with Firmware Engineering, including:
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CC-CV charging curves
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Temperature-dependent charge rate limits
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Fast-charge protocols
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Float and maintenance charging strategies optimized for data center duty cycles
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Design thermal interfaces between battery cells and the enclosure using:
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Thermal pads
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Gap fillers
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Heat spreaders
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Dedicated thermal pathways
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Collaborate closely with the Thermal / Mechanical Engineering team.
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Conduct pack-level FMEA and battery safety analysis.
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Define and execute abuse testing protocols including:
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Nail penetration
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Crush testing
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Overcharge testing
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External short-circuit testing
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Validation adapted specifically for solid-state battery behavior
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Develop accelerated aging and life-cycle validation protocols for data center applications, including prolonged high-State-of-Charge float conditions with infrequent high-power discharge events.
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Serve as the primary liaison with the cell development team, translating pack-level requirements into cell-level specifications and feeding laboratory and field performance data back into future cell development.
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Support safety certification efforts including:
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UL 1973
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UL 9540A
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What You Bring
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Required Qualifications
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8+ years of experience designing battery packs or battery modules, with at least one product successfully validated through prototype testing or production.
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Hands-on Battery Management System (BMS) architecture experience. (PCB layout experience is not required, but the ability to define system topology and component selection is essential.)
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Strong battery characterization and modeling experience, including:
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Impedance spectroscopy
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Capacity fade analysis
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Thermal characterization
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Experience with battery safety standards, particularly:
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UL 1973
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Exposure to UL 9540A strongly
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Proficiency in pack-level mechanical and thermal design using:
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SolidWorks
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Creo
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Equivalent CAD platforms
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Thermal simulation experience is a plus.
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Comfortable making engineering decisions while working with evolving battery cell specifications and incomplete technical data.
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Qualifications
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Experience with solid-state, lithium-metal, or other next- battery chemistries, including research environments.
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Experience designing battery systems for:
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Data centers
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Telecom backup power
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Stationary energy storage
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Understanding of float-then-discharge duty cycles compared to electric vehicle cycling.
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Familiarity with electrochemical modeling tools such as:
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COMSOL
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PyBaMM
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AutoLion
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Equivalent platforms
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Experience with IEC 62619 industrial battery safety standards.
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Applications engineering experience at a battery cell manufacturer, translating cell performance into production pack designs.
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Knowledge of functional safety principles including:
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IEC 61508
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Equivalent standards
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Why This Role Matters
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You sit at the center of the engineering organization. The Power Electronics Lead depends on your voltage windows, current limits, and battery performance requirements. The Firmware Engineer relies on your Battery Management System algorithms and protection strategies. The Thermal / Mechanical Engineer depends on your cell thermal requirements and packaging constraints. The Cell Development Team relies on your pack-level feedback to continuously improve cell performance.
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Most importantly, the safety, reliability, and long-term longevity of solid-state batteries deployed in hyperscale AI data center racks will ultimately be defined by your engineering decisions. This role is central to delivering the core technology differentiator of the entire platform.