Principal Battery Systems Engineer
Senior technical lead who owns the architecture, roadmap, and engineering standards for ON.energy's battery energy storage (BESS) product line — the battery backbone of its medium-voltage UPS systems protecting grid-connected data centers. Day to day: running multiple product cycles, doing deep component sizing and protection design, driving vendor strategy, and representing engineering externally
- Compensation
- Not disclosed
- Location
- Houston, Texas, United States; Mexico City, Mexico City, Mexico; Miami, Florida, United States; Reston, Virginia, United States
- Work setup
- Not specified
- Seniority
- Principal
- Employment
- Not specified
- Experience
- 10+ years
- Category
- Software engineering
- Posted
Skills
Must have
- Bachelor's degree in Electrical Engineering, Power Electronics, or closely related technical field
- 10+ years hands-on engineering experience in BESS, power electronics, UPS, or comparable mission-critical industrial power systems, operating with minimal direction in a senior role
- Owned multiple product development cycles end-to-end; personally designed and integrated a BESS at system level through commissioning into live operation, with products still in the field
- Architecture-level decision authority on previous BESS equipment — made trade-off calls, not just executed others' architectures
- Deep, demonstrable skill in detailed component sizing: fuse coordination, busbar sizing, protection device selection, thermal sizing for enclosed cabinets
- Fluency producing and reviewing SLDs, GAs, schematics, and panel layouts; expert with AutoCAD or equivalent E-CAD; comfortable with mechanical drawings
- Track record running strategic vendor relationships through design, FAT, serial production, and post-deployment escalation
- Excellent written and verbal communication — specs, technical positions, design review leadership, board-level briefings
- Willing to travel up to 25–30% for FAT inspections, site commissioning, customer engagements, and vendor reviews
Nice to have
- MS degree preferred
- Direct experience with data center / UPS / mission-critical power or utility-scale BESS at the architecture level
- Active involvement in standards bodies (UL, IEC, NFPA, IEEE working groups, CSA TC committees) or technical conference contributions
- Patents, peer-reviewed publications, or other evidence of recognized technical depth
- PE license
- Familiarity with UL 9540 / 9540A, NFPA 855, IEC 62619, IEEE 1547, NEC Article 706 and relevant target-market codes
- Experience standing up or scaling structured PLM, ECR/ECN, and design-review processes
- Multi-domain depth — BMS/cell engineering, PCS/power electronics, thermal/mechanical — alongside the EE core
Full description
ON.energy is setting the standard for large load interconnection. ON’s patented AI UPS™ is a medium-voltage UPS that serves as a firewall, protecting the data center from the grid, and the grid from the data center. With multiple gigawatts currently under construction, we are enabling grid-safe data centers.
Principal Battery Systems EngineerRole Overview
We're looking for a Principal Engineer to set the technical direction for our BESS product line and to own the product roadmap across multiple concurrent development cycles. This is the senior technical voice on the product team: you'll architect new products, resolve the hardest engineering trade-offs, set the engineering standards others work to, and represent ON.energy's product engineering externally — to vendors, customers, certifying bodies, and the broader industry. You should be comfortable operating with minimal direction, holding the bar on technical quality, and moving multiple product cycles forward in parallel without losing the thread on any of them.
What You'll OwnArchitecture & Technical Direction
- Set the architecture for the BESS product line and own the technical roadmap across multiple concurrent product cycles.
- Make the hard trade-off calls — cost vs reliability, performance vs lead time, standardization vs customization — and document the reasoning so future decisions inherit context.
- Define the engineering standards, design rules, and review gates that other engineers on the team work to. Own the product-engineering bar.
- Approve major design changes; act as the final technical authority on the change baseline.
Multi-Product Development
- Run multiple product development cycles in parallel — concept through prototype, FAT, field deployment, and revision — without losing depth on any of them.
- Drive cycle cadence: decide what ships when, where the technical risk lives, what gets parallelized vs sequenced.
- Identify and execute the next-generation product moves — higher voltage class, alternate chemistries, new form factors — ahead of customer demand.
Detailed Engineering Depth
- Personally own the hardest pieces of work: novel architectures, first-of-kind designs, advanced component sizing (fuse coordination, busbar thermal optimization, protection coordination across cascaded systems), cabinet thermal modeling, and complex protection schemes.
- Review and approve detailed engineering drawings — SLDs, GAs, schematics, panel layouts — at the level required to sign off, not just consult.
Vendor & Supply Chain Strategy
- Own the strategic relationships with key vendors — battery, PCS, BoP. Decide the architecture of those relationships: sole-source vs dual-source, co-development depth, IP boundaries.