The Ford Mach E is built on the Global Electrified 1 platform that in itself is a heavily modified version of the C2 platform. The C2 underpins the Focus and Kuga.
Based on the fact that the structure was originally designed for internal combustion engines it has required some substantial modification to enable it to work for a full electric vehicle.
Modular vs Dedicated BEV Platform
The modular vs dedicated BEV platform is an interesting problem facing automotive OEM’s as they balance their need to produce Internal Combustion Engine (ICE) vehicles and Battery Electric Vehicles (BEV).
However, as the BEV market matures it is quite obvious that the dedicated platform will have more financial advantages.
The modifications to the steel body structure are extensive and the presentation by Mark Mikolaiczik [1] shows the level of changes. The increased weight in the structure has been offset to some extent by selecting lighter materials for the closures.
The 91kWh usable (98.7kWh gross) battery pack weighs 670kg, the cells making up 399kg of that total. This pack has a cell to pack mass ratio of 59%. This is a significant portion of the total vehicle mass.
Energy Management in Frontal Structure
- The transition from an ICE to a BEV powertrain results in a 36% increase in vehicle test mass and energy input into the structure.
- Achieving the proportions of a BEV yielded a 10% reduction in the allowable crush space of the frontal structure when compared to a comparable ICE vehicle.
These two factors result in a 53% increase in the loads needed to be managed by the front rails.
Also, when we look at the underside of the vehicle we see that the battery has a significant footprint. Normal for an EV in this class.
The image below shows how significant the torque boxes needed to be to manage the front end crash and offset-barrier requirements.
This post has been built based on the support and sponsorship from: About:Energy, AVANT Future Mobility, Quarto Technical Services, TAE Power Solutions and The Limiting Factor.
The sills are also very substantial in this design to protect the passenger and battery during a side pole impact.
Again looking reference [1] there has been some substantial stiffening of the sills.
The battery frame itself has very large sections for the side rails. The Munro teardown of the vehicle shows that this is a fabricated aluminium battery enclosure with aluminium extrusions for the side rails and an aluminium lower panel.
When we look into the body structure there are extra east-west beams there too.
The 36% increase in test mass feels very high and some of this is likely to be due to this being a modified ICE structure rather than a dedicated ground up BEV. The battery pack has a gravimetric energy density of 147Wh/kg, a long way off the Tesla 171Wh/kg. As per the old adage, mass creates mass. A better battery cell, pack design and assembly could be 100kg lighter. This would have reduced the crash test mass, thus reducing forces and energy that the body has to deal with, hence lighter body structure.
References
- 2021 Mustang Mach-E, GDIS, Mark Mikolaiczik, Ford Motor Company
- Ford Mustang Mach-E review, AutoCar
- Mach-E Teardown Wrap Up, Munro Live