Scooter Inverter

Objective

Constraint Awareness

Background

Recognizing a need for reliable power in high-mobility environments, I repurposed a decommissioned external scooter battery into a high-capacity portable power station. By integrating the battery with a power inverter, I engineered a mobile solution to overcome the limited availability of charging infrastructure at my university, ensuring uninterrupted productivity for my laptop and other essential devices.

The Scooter Inverter was engineered to provide high-performance portable power for everyday appliances. The project successfully navigated the complex trade-offs between technical efficiency, manufacturing affordability, and modern industrial design.

Have high-power battery capable of charging most appliances
Maintain portabilty
Adequate Safety Features
Spend less than $60
Employ electrical concepts

Key Design Decisions

Engineering Methodology Cost Awareness Performance Tradeoff Circuits

Buck Converter Selection

A buck converter was used to efficiently step down the scooter battery voltage to the inverter’s operating range. Due to unknown battery output specifications, a 360 W inverter was intentionally oversized to ensure sufficient power for expected loads without overloading the converter.

Inverter Selection

A 300 W inverter was selected to meet the power requirements of the intended load while maintaining a reasonable size and weight. The cigarette plug provides a convenient connection for the inverter to the scooter's power system.

Other Materials

A 30 A switch was soldered to the buck converter as a safety kill switch to disconnect the power in case of an emergency. It also ensures the buck is not constantly powered on when the inverter is not in use.

30 A blade fuses were installed to protect the circuit from overcurrent conditions.

The case was 3D printed for cost effectiveness and to allow for quick prototyping and iteration.

Results

Experimental Validation

Extensive testing was conducted to validate the performance and safety of the scooter. This included bench testing of individual components and system-level testing to ensure all parts functioned as expected under typical usage scenarios.

The stress test results are as follows:

17 A current draw for 1 minute before BMS trips overheat battery protection
8 A of current draw for prolonged operation
Efficiency: ~85%

Conclusion: The scooter inverter performs well under typical usage scenarios, with a high efficiency and adequate safety features.

200 W maximum power
100 W continuous power
110 V (AC) maximum voltage

These results demonstrate the scooter's ability to deliver consistent power while maintaining safety and efficiency.

Skills Demonstrated

Power Electronics Inverter Systems Battery Management Systems (BMS) Circuit Design Load Analysis Electrical Safety Design Soldering & Wiring Engineering Design Process Trade-off Analysis Hardware Prototyping Product Design Design for Portability Efficiency Analysis Stress Testing & Validation Experimental Testing Troubleshooting Electrical Systems Spec Estimation Under Uncertainty Rapid Prototyping 3D Printing Design for Manufacturability (DFM) Low-Cost Product Development Cost-Constrained Engineering Hardware Project Development End-to-End Product Development Safety-Critical Design