The battery pack is the most complex, most expensive, and most safety-critical component in any electric racing car. It must simultaneously deliver extraordinary bursts of power, survive the mechanical stresses of racing, protect the driver in the event of an accident, and do all of this while adding as little weight as possible to a vehicle where every kilogram costs lap time.
These competing demands — power, safety, and weight — define the central engineering challenge of EV racing battery design. At Drayson Racing Technologies, our battery programmes across land speed record attempts and Formula E concept development have given us direct experience of how these trade-offs play out in practice.
Why Battery Weight Is the Central Design Constraint
In a conventional internal combustion race car, the heaviest single component is typically the engine — perhaps 120–180 kg for a high-performance racing unit. In an electric race car, the battery pack routinely accounts for 250–400 kg of the car’s total mass, depending on the energy storage requirements of the event.
This weight penalty cascades through the entire vehicle design. A heavier car requires stronger, heavier suspension components. It demands more powerful brakes. It changes the car’s centre of gravity and its dynamic behaviour through corners. Every kilogram saved in the battery system is therefore worth more than a kilogram saved anywhere else on the car.
The weight challenge was central to the B12/69EV programme, where the target of exceeding 200 mph required both maximum power output and minimum vehicle mass. The full story of how those demands were balanced is told in our post on how the B12/69EV broke the 204 mph electric land speed record.
Composite Enclosures: Carbon Fibre as Structure and Safety Cell
The enclosure that houses the battery cells in an EV racing application must serve two functions simultaneously: it is a structural component of the vehicle (contributing to the car’s torsional rigidity) and a safety cell (protecting the cells from intrusion in an accident and containing any thermal event within defined limits).
Carbon fibre reinforced polymer (CFRP) composite is the dominant material choice for high-performance EV battery enclosures. Its specific stiffness — stiffness per unit of weight — is approximately five times greater than aluminium and four times greater than steel. This means a CFRP enclosure can achieve the required structural performance at dramatically lower mass than a metallic equivalent.
The layup design of the CFRP — the orientation and sequence of fibre plies — is optimised using finite element analysis to provide maximum impact resistance in the most likely accident scenarios while minimising unnecessary material and weight. Modern racing battery enclosures are genuinely extraordinary engineering artefacts, as structurally sophisticated as any component on the car.
Cell Chemistry: Power Density vs Energy Density
Not all lithium-ion cells are the same. The two primary performance axes in cell selection are energy density (how much energy per kilogram the cell can store) and power density (how much power per kilogram the cell can deliver instantaneously).
Road car batteries are optimised for energy density — the goal is maximum range per kilogram. Racing batteries require a fundamentally different balance. A land speed record car needs extraordinary instantaneous power — the ability to discharge a large fraction of its stored energy over a very short time period. For this application, cells with lower energy density but dramatically higher power density are the correct choice, even though they provide less total range.
This trade-off is one of the less-understood aspects of EV racing battery engineering, and one of the areas where motorsport experience provides direct value to road car development — by exploring the full spectrum of cell chemistry performance rather than optimising narrowly for a single metric.
Thermal Management: The Difference Between Performance and Failure
Lithium-ion cells perform optimally within a relatively narrow temperature window — typically 20–40°C. Below this range, internal resistance increases and power output falls. Above it, cell degradation accelerates and, in extreme cases, thermal runaway becomes a risk.
In a racing context, the thermal management system must handle two distinct scenarios: warming the pack to optimal temperature before a run (cold-soak is a real risk in British motorsport conditions) and removing heat during and after the extreme discharge event of a race or record attempt.
DRT’s thermal management approach uses a liquid-cooled system with channels integrated directly into the structural composite of the enclosure — a design that combines cooling function with structural efficiency, adding thermal management capability without the weight penalty of a separate cooling system.
Safety: Beyond Crash Protection
Battery safety in a racing context extends beyond crash protection. Thermal runaway — an exothermic chain reaction within a cell that can propagate to adjacent cells — is the primary safety concern in EV racing battery design. Preventing propagation requires a combination of cell-level protection (each cell individually fused), module-level separation (fire-resistant barriers between groups of cells), and pack-level venting (controlled pathways for gas release that direct energy away from the driver).
The regulations governing battery safety in electric motorsport have evolved rapidly, driven partly by the real-world testing that racing provides. DRT’s experience with high-rate discharge battery systems has contributed directly to the understanding of failure modes that now informs FIA regulations for electric racing categories.
The safety engineering principles developed in racing battery programmes have direct relevance to road car applications. The trickle-down from race to road in battery technology is explored in our post on what race EV R&D means for your next car.
The Future: Solid State and Beyond
The next generation of racing battery technology is solid-state — replacing the liquid electrolyte in current lithium-ion cells with a solid ceramic or polymer material. Solid-state cells offer higher energy density, faster charging, greater thermal stability, and significantly reduced fire risk. They are, at present, expensive and difficult to manufacture at scale.
Motorsport will be one of the proving grounds for solid-state battery technology. The demanding performance requirements of electric racing, combined with the relatively small production volumes that make experimental technologies economically viable to deploy, make it the ideal environment for validating solid-state systems before road car production.
This is the pattern that has characterised every major automotive technology transition: the racetrack first, then the road. We explore this pattern in detail in our analysis of motorsport as a laboratory for competitive low-carbon racing.
🔬 Follow Drayson Racing Technologies
Drayson Racing Technologies continues to push the boundaries of electric motorsport and sustainable mobility R&D. Explore our full archive of technical and policy insights, and follow our ongoing programmes in EV performance, wireless charging, and competitive low-carbon racing.
👉 Read more from Drayson Racing Technologies — engineering insights, race records, and the future of electric performance.
