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). The trouble is we are in a world that still wants both vehicle options and vehicle platforms are expensive.
- One body design and multiple drivelines
- Flexible vehicle configuration to match sales
- ICE designed to have an ~200kg to 300kg engine and gearbox that connects with the barrier and energy absorbed
- EV has a large battery pack where all of the energy has to be absorbed in front end
- Difficult to design for ICE and BEV without significant compromises and lots of added structure
- Smaller modules -> smaller cells to make use of the volume and achieve kWh.
- Need to use tunnel and fuel tank volume and hence double stack cells => more structure.
- Complex cooling system => more connectors and parts.
- Difficult to achieve even cell temperatures
- Difficult to seal perimeter of pack
- More of and longer HV busbars
- More structure required to maintain durability and integrity in crash.
Example: VW eGolf
- Only suitable for BEV.
- Difficult to react fore-aft crash forces from engine bay through flat floor on dedicated BEV.
- Body sills and battery structure aligned to react side crash, allows battery to grow further outwards.
- Simple flat rectangular pack design.
- Simple flat battery case seal.
- Lower cell to cell temperature variation.
- Simpler cooling system.
- Larger battery cells, reduced cost and complexity.
- High energy density (volumetric and gravimetric) pack design.
- Lower cost battery.
Example: Tesla Model 3
The modular vs dedicated BEV platform is an interesting business and technical problem to balance. Both have risks and benefits that need to be balanced. Each company will have their own reasons for preferring a particular approach.
However, as the BEV market matures it is quite obvious that the dedicated platform will have more financial advantages.
Battery Pack Generations
When we look at automotive battery pack design there have been a number of pack generations. The general theme is to simplify and hence reduce the cost.