eFitSYS is an innovative start-up and spin-off of Politecnico di Torino. The first product realeased on the market will be the eFit Kit for the electric retrofit of a car.
The eFit Kit is the retrofit solution developed and produced by ElectroFit Systems that retains the key components of the original vehicle such as the differential, gearbox, and suspension, while substituting the combustion engine and the gasoline tank with the components of a fully electric powertrain.
The story
In December 2023 the thesis of the neo-engineer Davide Ciullini “Design of an electric powertrain for the requalification of vehicles with internal combustion engine” tells about a project that has much more distant origins and constitutes just one of the bricks of the ElectroFit Systems project. The speaker and protagonist of the project is Prof. Stefano Carabelli, from the Department of Control and Computer Engineering of Politecnico di Torino who explained us in detail the birth and the development of the initiative, whose protagonist bestselling in its segment all over Europe for many decades has been the iconic Fiat Panda. The context is clear: urban and suburban areas are where restrictions to contain toxic emissions are most needed. In these zones, speeds are controlled, and typical daily driving distances are limited by geography. Small electric vehicles are the most rational
solutions for urban mobility. Lower speed and autonomy requirements allow for powertrains with lower power and smaller capacities.
The project
ElectroFit Systems powertrain development is based on a well defined process that combines dynamic models of the vehicle with test bench measurements on the real system before installation on the vehicle to optimize performance and reliability.
The challenge
«During the design development, we were called to deal with two crucial aspects mainly: integrating an electric powertrain into internal combustion engine vehicles and designing new components to suit the vehicle’s existing structure. From the technical point of view, this implies a deep understanding of the vehicle’s operation dynamics and the design of sophisticated systems like battery packs, power boxes and a traction group to be connected with the electric motor. Facing this challenge has needed a constant process of experimentation and optimization. Moreover, the project has been carried out by trying reusing original components and “requalifying” them in a new electric form; this approach has allowed saving” also components of relevant importance such as the vehicle’s original transmission. Therefore, we understand how the recycling concept is one of the design pillars», explained the engineer, David Ciullini.
The components
The architecture of eFit Battery Pack: prismatic ternary cells with high energy density arranged in parallel and series into modules of different size and capacity. The Power Box that contains the power electronic components (fuses, relays, junctions) to connect and manage the different subsystems including the onboard chargers for the Battery Pack 12 V legacy Service Battery.
The main characteristic of the Traction Group included in the eFit Kit is the integrated
assembly of the electric motor and inverter sharing the liquid cooling to optimize overall efficiency and performance.
Them, there is Vehicle Management Unit, the core of the eFit Kit to manage the interactions of the different components of the traction system and the driver commands.
Lastly, the regular shape of the Panda body surface naturally calls for the integration
of solar panels to provide up to 15 km of additional range on clear and sunny day. The solar panels have a flexible structure that allows them to suit the body surface and features a magnetic bottom to be easily fixed on and removed from the vehicle roof.
