The Project:

EFT Mobility executed a battery system architecture for a hybrid-electric helicopter. A single turbine helicopter is extended by a parallel battery electric powertrain, which is directly connected to the main shaft of the helicopter. In case of failure of the turbine, the electric powertrain can power the helicopter for a few minutes, enough time to execute a safe emergency descent scenario.

Requirements Definition

Step 1: Definition of Requirements

In the beginning, the exact specifications for the battery electric powertrain had to be defined together with the customer. This includes the exact desired flight profile, derived power profile, and any volumetric, gravimetric, and certification requirements.

Energy Storage Selection

Step 2: Energy Storage System Selection

In order to evaluate all possible solutions, we started the study with a high-level benchmark overview of all available energy storage systems and an analysis of their relevant key characteristics.

Through step-by-step downselection, we identified the precise energy storage technology and then the exact chemistry composition which is best suitable for the use case.

Image source: Wikimedia Commons. The original file can be found here.

Battery Supplier

Step 3: Supplier Pre-Selection

Based on the selection of the best battery chemistry, we evaluated possible module and battery pack providers. Evaluating the product maturity, availability, and adherence to the relevant standards we chose the best suppliers for the application.


Step 4: Modelling of Battery System

Once specific battery modules had been identified, battery electric powertrain prototyping was conducted. This includes designing the battery with its specific discharge curves, internal resistance, and capacitance.

Through the prototyping, the feasibility of the battery module selection can be confirmed and adjusted as necessary.

Finally, a battery design was identified. One that satisfies the requirements and is available on the market.