Skip to content 
As Munro & Associates’ latest teardown reveals, Tesla’s 4680 battery pack represents a giant leap forward in electric vehicle (EV) technology. And it’s packed with surprising design decisions. Let’s go through the intricate process of uncovering the real story hidden beneath the pink foam insulation. Digging into the 4680 pack reveals how Tesla is pushing boundaries in design, manufacturing, thermal management, and recycling.
Challenging the Teardown: Blasting Through the Foam
The first challenge facing the team was the dense pink foam encapsulating the 4680 battery cells. To remove it without damaging key components, the team employed a dry ice blaster—an innovative, viewer-suggested solution. Even with this high-tech method, the process proved difficult, highlighting how robustly Tesla integrated the foam for structural support and thermal management.
Removing the foam revealed that the cells aren’t mounted directly against the outer battery case. Instead, there’s a gap, filled with side foam, and the structure consists of an aluminum lower casing and a steel upper casing—an interesting choice of materials for durability and weight optimization.
Layered Protection: ABS Base, Mica, and More
Beneath the 4680 cells, Munro’s team uncovered a thin layer of mica and a black ABS plastic base. Mica provides critical thermal insulation, while ABS plastic offers a lightweight, heat-resistant foundation. Notably, Tesla directs the cells’ venting downward. This safety feature mitigates the risks of overcharging or thermal runaway by directing dangerous gases away from the passenger compartment.
Adding to the innovation, the team found bus bars and collector plates at the cell tops. Removing an upper plastic plate (suspected to be glass-filled nylon) proved difficult, reinforcing Tesla’s focus on durability and heat resistance in material choices.
Parallel Connectors and Micro-Welds
A major highlight was the discovery of Tesla’s use of laser-welded parallel connectors. Each set of three cells connects via small squares of precision welds. By carefully disconnecting these welds, Munro’s team could safely isolate individual modules—critical for both safety and serviceability.
The deliberate design choice to use smaller gauge flat wires for monitoring temperature and voltage also stood out. These tiny wires, robust yet sacrificial, act as inherent fuses—melting in the event of serious faults without the need for traditional fuses, a strategy Tesla has employed since the Model 3 and Model Y.
Cooling Strategy: Not Quite Bottom Cooled
Early assumptions suggested Tesla might employ a bottom-cooling approach for the 4680 pack. However, excavation revealed a more traditional side-cooling layout using visible thermal lines. Although some debate remains about certain components—like whether a hidden module is a body control module or a battery control module—the overall thermal strategy reflects Tesla’s methodical evolution rather than radical reinvention.
Modular Design and Thermal Mitigation
Inside the pack, Tesla organized the 4680 cells into four distinct modules, separated by barriers that appear to be fiberglass phenolic materials. These barriers likely serve as thermal propagation mitigation, preventing runaway heat from cascading across the entire battery.
While Munro originally speculated Tesla would build a “brick” of cells with no modules, the presence of these dividers suggests that Tesla is balancing manufacturability, serviceability, and safety—hallmarks of lean manufacturing principles.
Less Fasteners, More Quality
One of Sandy Munro’s long-standing engineering mantras is that threaded fasteners are a major source of manufacturing defects. True to Tesla’s disruptive style, the 4680 battery pack uses minimal mechanical fasteners, relying instead on laser welding, adhesives, epoxies, and structural glues.
This approach significantly reduces opportunities for leaks, loosening, or misalignment—common failure modes in conventional automotive assemblies. Munro shared that, based on Ford studies he participated in, approximately 75% of major vehicle failures were due to issues related to threaded fasteners. Tesla’s methodical elimination of this risk improves both manufacturing efficiency and vehicle longevity.
Recycling Strategy: High-Quality Ore
A recurring concern from the EV community revolves around the recyclability of next-generation batteries. Munro addressed this head-on, explaining that Tesla designed the 4680 pack with end-of-life recycling in mind.
The plan involves cryogenic freezing the pack in liquid nitrogen, making the entire structure brittle. It’s then pulverized and separated through density-based floatation techniques. Aluminum, steel, lithium, and other valuable elements can be recovered almost entirely, restoring them to near-pristine elemental form. This recycling process treats the battery pack much like premium ore from a quarry—an efficient, environmentally responsible approach that aligns with Tesla’s broader sustainability goals.
Final Cell Count Estimate
The team estimates that each of the four modules contains 204 cells. Arranged in a grid of 34 by 6, this gives a preliminary total of 816 or 828 cells (depending on final counts after removing a suspected nylon-and-glass plate). This figure reaffirms the significant energy density and power potential of Tesla’s new 4680 packs, offering better range, faster charging, and improved durability.
Tesla’s Relentless Innovation
Throughout the battery pack teardown, one theme about the 4680 remained clear: Tesla doesn’t stand still. Each battery pack the Munro team investigates feels like it came from a different company entirely. This reflects Tesla’s agile, boundary-pushing approach to automotive engineering. The 4680 battery showcases not just incremental evolution, but radical reinvention across cooling strategies, cell packaging, thermal safety, and manufacturability.
Tesla’s commitment to lean design, cost reduction, quality improvement, and recyclability is unmistakable. This teardown highlights how Tesla continues to set the standard. Not just in EV performance, either. But in how the future of automotive technology is being engineered from the ground up.
Teardown Takeaways for the 4680 Battery Pack
- Material Optimization: Smart use of aluminum, steel, ABS, mica, and glass-filled nylon.
- Thermal Management: Focused on side-cooling with effective runaway mitigation strategies.
- Manufacturing Excellence: Minimizing fasteners to enhance quality and simplify recycling.
- Sustainability Commitment: Designing for easy, efficient recycling into high-quality elemental ore.
Tesla’s 4680 battery pack stands as a benchmark in modern EV design. For automotive engineers, investors, and technology followers, it’s a powerful reminder: the real breakthroughs often happen where you can’t immediately see them—under the foam.
Want more exclusive insights into EV innovation? Keep it on Munro & Associates for expert teardowns, cost breakdowns, and the latest lean manufacturing analysis from the world’s top automotive engineers.