Product Development Engineer – Compact Portable Phone Charger (Battery + PCB + CAD)

I am looking for an experienced product development engineer or multidisciplinary engineering team to develop a compact rechargeable portable phone charger from engineering feasibility through a complete prototype-ready digital engineering package. The primary challenge is miniaturization and integration, not inventing new battery or charging technology. The goal is to intelligently integrate proven battery, charging, protection, PCB, connector, and mechanical technologies into a compact, reliable, premium consumer product. Product Requirements The product will incorporate: * Rechargeable Li-ion/LiPo battery * Direct phone-charging connection * USB-C recharging * Battery charging/protection and power management * Compact PCB/electronics * Custom enclosure * Internal component packaging * Simple LED illumination/status functionality * Battery-level indication * Compact, lightweight consumer-product form factor The target overall size is approximately an Apple AirPods charging case or smaller if technically feasible. This is a size benchmark rather than an absolute dimensional requirement. Maintaining a genuinely compact and portable product is more important than maximizing battery capacity. The product is intended to provide useful emergency phone charging, not compete with traditional large power banks on maximum mAh capacity. Engineering Philosophy I prefer using proven commercially available components and technologies wherever practical. I am not looking to unnecessarily reinvent existing portable-charging technology. A custom PCB is acceptable and may be necessary for miniaturization, but custom engineering should be introduced where it provides a meaningful advantage in size, reliability, performance, cost, or manufacturability. The battery, PCB, charging electronics, connectors, enclosure, and mechanical architecture should be developed as one integrated product, not independently. Development Structure I currently envision two milestones, although I am open to recommendations from experienced engineers if there is a strong reason to structure the project differently. Milestone 1 — Feasibility & Engineering Direction Expected work includes: * Battery selection and realistic capacity analysis * Power/energy budget * USB-C charging architecture * Battery protection and power management * Direct phone-charging architecture * Preliminary component selection * Internal component packaging/3D architecture study * PCB requirements assessment * Approximate dimensions and weight * Thermal and structural considerations * Preliminary BOM/cost direction * Manufacturing/assembly considerations * Relevant battery safety and transportation considerations * Identification of major technical risks and trade-offs * Clear Go/No-Go engineering recommendation The objective of this milestone is to determine whether the complete product can realistically coexist within the targeted compact form factor before investing in detailed engineering. Milestone 2 — Prototype-Ready Engineering If feasibility is confirmed, development should proceed through the complete detailed engineering required for physical prototyping, including as applicable: * Detailed electrical architecture * Schematic design * Custom PCB design/layout * Gerber and PCB manufacturing files * Final component-level BOM * Complete enclosure/mechanical CAD * Battery, PCB and connector integration * STEP/STL and native/editable CAD files * Technical/manufacturing drawings * Assembly documentation * DFM/DFA review * Component specifications * Prototype fabrication notes * Complete prototype-ready digital engineering package The final package should be sufficiently complete for a separate qualified prototype manufacturer to physically fabricate and assemble the product. Physical prototype manufacturing is not required as part of this job. Ideal Experience I am particularly interested in engineers or teams with direct experience developing: * Portable phone chargers / power banks * Compact rechargeable consumer electronics * Battery-powered accessories * Wearable electronics * Small USB-C products * Other highly space-constrained electronic products Experience taking products from concept → engineering → physical prototype → manufacturing is strongly preferred. Required Capabilities You or your team should be capable of handling both: Electrical Battery integration, charging/protection, USB-C, power management, PCB design, component selection and manufacturing documentation. Mechanical Compact internal packaging, enclosure design, CAD, connector integration, assembly strategy, tolerances, materials and DFM. I prefer one engineer/team capable of taking responsibility for the complete integrated product rather than requiring me to independently coordinate separate electrical and mechanical engineers. When Applying Please answer the following: 1. Have you personally developed a portable charger, power bank, or similarly compact rechargeable consumer electronic product? Please provide examples. 2. What specifically were you responsible for on those products? 3. Have you designed custom PCBs for highly space-constrained battery-powered products? 4. What experience do you have with Li-ion/LiPo batteries, USB-C charging, battery protection and power management? 5. Can you handle both the mechanical and electrical development required for this project? If a team is involved, explain who handles each area. 6. Have products you engineered progressed into working physical prototypes or mass production? 7. Can you provide a complete prototype-ready package for handoff to a third-party manufacturer? 8. Please describe how you would approach minimizing product size while maintaining useful charging capability, reliability, safety and manufacturability. 9. What milestone structure would you recommend for this project? Please do not submit a generic proposal. I am particularly interested in seeing examples of compact rechargeable consumer products you have actually engineered, including internal electronics/PCB and mechanical enclosure work where possible. Additional confidential product details and design references will be shared privately with shortlisted candidates.