The Challenge
Context: A micromobility fleet needed a way to secure high-value battery packs against theft while allowing authorized “Swap Teams” to replace them in seconds.
The “Halfdome” project was an electromechanical battery lock designed for severe abuse:
- Vibration: It had to stay locked while bouncing down potholes at 20mph.
- Security: It needed to resist pry attacks and picking.
- Environment: It lived outside, exposed to rain, salt spray, and road grime.
Engineering Approach
We designed a custom motorized locking dog mechanism rather than a simple solenoid (which can vibrate open).
- Gearbox Design: I engineered a high-reduction spur gear train driven by a small DC motor. This provided massive holding torque to the locking pin without requiring continuous power to stay locked (bi-stable design).
- Sealing: The entire mechanism was housed in a glass-filled nylon enclosure with an ultrasonic weld path, achieving IP67 ingress protection.
- Feedback: Integrated Hall Effect sensors provided closed-loop confirmation of “Locked” and “Unlocked” states to the main vehicle controller.
Impact
This mechanism became the standard retention system for the fleet.
- Reliability: >10,000 cycle life tested under vibration load.
- Security: The non-backdrivable gear train made forced entry nearly impossible without destroying the latch.
Project Artifacts
:::note[Specs]
- Actuation: DC Motor + Gearbox
- IP Rating: IP67
- Cycle Life: 10k Cycles
- Lock Force: >500N :::