The Battery Revolution: Inside BMW’s Strategic Partnership with Rimac for the New i7

The automotive landscape is shifting, and the BMW Group is positioning itself at the vanguard of this transformation. With the forthcoming update to its flagship electric luxury sedan, the BMW i7, the Munich-based manufacturer is introducing a major technological leap: a high-voltage battery system developed in close collaboration with Rimac Technology. This partnership, which merges BMW’s heritage of vehicle integration with Rimac’s prowess in high-performance electrification, is set to redefine expectations for range, charging efficiency, and industrial scalability in the premium EV segment.

Scheduled for an official unveiling at the Auto China 2026 on April 22, the revamped i7 serves as more than just a model refresh. It is a testing ground for next-generation battery architectures that will eventually trickle down to the highly anticipated “Neue Klasse” vehicle platforms.

Core Innovations: The 4695 Cell and Gen6 Technology

At the heart of this advancement lies the introduction of cylindrical lithium-ion cells in the 4695 format—measuring 46 mm in diameter and 95 mm in height. These cells represent the pinnacle of BMW’s sixth-generation (Gen6) eDrive technology.

By transitioning away from the prismatic cells utilized in the Gen5 architecture, BMW has achieved a roughly 20% increase in volumetric energy density. This shift to a cylindrical form factor is not merely a change in geometry; it is a fundamental shift in engineering philosophy. Cylindrical cells offer superior structural stability and, crucially, enhanced modularity. Unlike prismatic cells, which are often bespoke to specific vehicle floor-plans, the 4695 format allows for a standardized approach that can be scaled across various vehicle segments, reducing production complexity while maximizing output.

The Hybrid Architecture

Perhaps the most intriguing aspect of this project is the integration strategy. BMW is not abandoning its current infrastructure entirely; instead, it is employing a "hybrid architecture" that pairs the cutting-edge Gen6 cells with the proven Gen5 modular casing system. This allows BMW to leverage existing manufacturing workflows in its Dingolfing plant while reaping the performance benefits of the new, more dense cell chemistry.

Chronology of a Strategic Alliance

The collaboration between BMW and Rimac is the result of years of quiet, intense development.

• Initial Concept Phase (2023-2024): BMW and Rimac identified the need for a specialized battery solution that could maintain the luxury standards of the 7 Series while significantly pushing the boundaries of range and charging.
• Facility Expansion (2025): Rimac invested approximately €130 million into a 15,000-square-meter production facility near Zagreb, specifically designed to handle the high-volume production of the new modules.
• Validation and Testing (Late 2025 – Early 2026): Rigorous testing of the battery-to-vehicle integration was conducted, focusing on thermal management and the communication between the battery management system (BMS) and the vehicle’s powertrain.
• Public Unveiling (April 2026): The official debut at the Auto China 2026 marks the first mass-market implementation of this joint technology.

Supporting Data: Efficiency and Charging Dynamics

The current BMW i7 offers a usable capacity of 101.7 kWh, yielding a WLTP-rated range of approximately 624 km. With the introduction of the new 4695 cells and their increased energy density, engineers are projecting a significant boost in performance.

Range Projections

Industry analysts suggest that the new architecture will likely push the i7’s range to between 700 km and 750 km on a single charge—an increase of more than 100 km over the current model. This is achieved without significantly increasing the weight of the vehicle, as the higher density of the cells allows for more energy storage within the same physical footprint.

Charging Performance (The C-Rate Factor)

A critical metric in the new battery’s success is the improvement in C-rates. By reducing the internal resistance of the cells, the new system allows for faster energy intake during DC fast-charging sessions. While the exact peak charging power has not been disclosed, the design improvements suggest a faster "charging curve," where the vehicle can maintain high power levels for longer durations before throttling down, drastically reducing stopover times for long-distance drivers.

Official Responses and Engineering Perspectives

Thomas Engelhardt, Senior Vice President of High-Voltage Storage Development at BMW, characterizes the project as a "tailor-made solution." He emphasizes that the development process was not about picking components off a shelf, but about the deep co-development of thermal management systems and power electronics to ensure the battery operates optimally within the heavy, high-luxury constraints of the i7.

Mate Rimac, CEO of Rimac Technology, echoes this sentiment: "Together, we have developed a high-voltage battery system that unlocks the full potential of these new cylindrical cells." For Rimac, this partnership serves as a validation of its business model: pivoting from a boutique supercar manufacturer to a global Tier-1 automotive supplier. By providing a scalable, high-performance battery solution for a major OEM like BMW, Rimac is signaling its intention to play a central role in the electrification of the mainstream luxury market.

Implications for the Future of Automotive Engineering

The BMW-Rimac partnership is a bellwether for the future of the European automotive industry. Several key implications arise from this collaboration:

1. Shortened Development Cycles

By outsourcing the specialized development of the battery module to a partner like Rimac, BMW is able to focus its internal resources on vehicle integration, software, and driving dynamics. This model of "co-opetition" and strategic sourcing is becoming increasingly vital as the pace of battery innovation outstrips the traditional five-to-seven-year automotive development cycle.

2. Supply Chain Decentralization

The logistics chain established for the i7—where cells and modules are manufactured in Croatia and then shipped to Dingolfing for final assembly—demonstrates the evolving geography of EV production. It highlights a move toward a more interconnected European supply chain where specialized hubs produce high-tech components, which are then integrated into the broader vehicle manufacturing ecosystem.

3. The End of "One-Size-Fits-All"

The hybrid approach (Gen6 cells + Gen5 structure) indicates that OEMs are becoming more pragmatic. Rather than waiting for a total overhaul of every manufacturing line, automakers are finding ways to modularize their upgrades. This ensures that the benefits of the latest battery chemistry can be realized sooner, providing a competitive edge in a market where range and charging speed are the primary differentiators.

Conclusion: A New Standard for Luxury EVs

The upcoming 2026 BMW i7 is not merely an updated luxury sedan; it is a manifestation of a new era of engineering collaboration. By successfully integrating the 4695-cell format and leveraging Rimac’s specialized manufacturing capabilities, BMW is addressing the "holy trinity" of electric vehicle concerns: range anxiety, charging speed, and scalable production.

For engineers and industry observers alike, the i7 will be the primary case study for how legacy manufacturers can successfully incorporate agile, high-tech partnerships into their production workflows. As the automotive world turns its eyes to Beijing this April, the focus will not just be on the design of the i7, but on the invisible, high-performance technology pulsing beneath its floor—a technology that sets the trajectory for everything that will follow in BMW’s electrification journey.