Reimagining EV Towing with Auxiliary Power

Electric vehicles are highly efficient under normal driving conditions, but towing creates a unique challenge. Added mass and aerodynamic drag can reduce range by more than half, limiting the practicality of EVs for trailers and long-distance hauling. SwitchBox set out to explore a research concept: a towable auxiliary energy module designed to supplement vehicle power during towing scenarios.

Project Objective

The goal of project eCamel (code name) was to design and validate a proof of concept trailer that demonstrated how additional stored energy could support extended EV range. The trailer housed a high voltage battery pack and power electronics configured to coordinate with the host vehicle. The objective was not to create a production ready solution, but to test integration methods that could inform future electrification strategies.

Mission Badge for the eCamel Project

Technical Challenges

One of the largest hurdles was using a production grade high voltage EV battery as the trailer’s energy source. At the time, limited information was available on its control strategies, so the team performed modifications to both the pack internals and its external interface to enable safe control within the prototype system.

Integrating an auxiliary energy source into an existing EV architecture also required careful planning. Space in production vehicles is tightly packaged, so the team developed methods to introduce additional HV elements in a way that fit cleanly and maintained functional integrity.

System Architecture

The trailer’s energy system was built around a high voltage battery pack coupled with a high voltage DC DC interface. Dual Advantix AFE modules were configured in parallel to support both buck and boost operation, aligning the trailer’s voltage with the host vehicle’s operating range. This provided stable HV energy transfer under varying conditions.

The physical connection used a NACS interface. Communication and control logic were adapted from CCS J1772 standards. Instead of implementing the full power line communication stack, the team designed a LIN based scheme over the signal line. LIN provided deterministic timing, reduced complexity, and enabled wake over LIN for seamless initialization of the trailer once connected to the vehicle.

Cross Disciplinary Engineering

The project required collaboration across all SwitchBox disciplines. Electrical engineers configured the HV pack and DC DC systems. Software engineers developed embedded code for communication and safety logic. Systems engineers coordinated overall architecture and requirements. Mechanical engineers scanned the vehicle, created CAD updates, and fabricated components to package the trailer and interface hardware.

Team size flexed from three to five engineers during most phases, scaling to around ten during peak integration and testing. Managing the entire workflow in house allowed rapid iteration and ensured alignment between electrical, mechanical, and software domains.

Results

The eCamel project successfully demonstrated that an auxiliary towable energy module can be integrated with an EV using standardized connectors and adapted communication protocols. Key outcomes included:

• Stable HV energy transfer using a dual DC DC configuration

• A communication and control framework built on LIN to simplify CCS sequencing

• Plug and play operation with automatic trailer wakeup and initialization

• Mechanical packaging that preserved vehicle integrity while accommodating new HV hardware

EV SUV towing the battery trailer over long distances

Significance

The project highlighted the feasibility of exploring auxiliary energy solutions as one pathway to address range loss in demanding use cases such as towing. For SwitchBox, it showcased the ability to deliver full system prototypes from requirements and architecture to embedded software, electrical design, and mechanical integration, all within one vertically integrated team.

Disclaimer

The eCamel project was conducted as a controlled research effort. It was not intended as a production ready system and does not represent an approved or recommended practice for towing and charging simultaneously. The work served as a feasibility study to explore engineering approaches and inform future development in the field of electrification.