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In the competitive world of electric vehicle (EV) manufacturing, every kilogram matters. Lighter vehicles accelerate faster, drive farther, and cost less to produce. In a recent Munro & Associates teardown, the team explored the Volkswagen ID.4 battery pack, uncovering significant opportunities for redesign, weight reduction, and cost savings — particularly through the use of polymer composites.
Setting the Stage: Weight Comparisons Across EVs
To put the ID.4 battery pack into context, let’s compare it to its competitors:
- Chevy Bolt EV: 57 kWh battery, 429 kg weight
- Tesla Model 3: 75 kWh battery, 442 kg weight
- Tesla Model Y: 75 kWh battery, 439 kg weight
- Volkswagen ID.4: 82 kWh battery, 489 kg weight
Despite offering slightly more energy storage, the ID.4’s battery weighs significantly more than the Tesla Model Y’s — a 50-kilogram difference. This excess weight translates to roughly $500 in added cost, based on industry averages of $10 saved per kilogram reduced.
For EV manufacturers and suppliers alike, this presents a major opportunity.
Understanding the Current Design
The existing ID.4 battery pack construction relies heavily on:
- Aluminum extrusions
- Precision castings
- Sophisticated welds
- Numerous threaded fasteners
While structurally sound, this architecture drives up weight and manufacturing complexity. Specific highlights from the teardown included:
- Heavy-duty extrusions welded to castings across the width of the pack.
- Special bolted connections using 8.8-grade necked bolts designed to reach the plastic state at installation — effectively turning the bolts into springs for optimal clamping.
- Strategic use of flow-drill fasteners, a clever solution that allows for fast, reliable connections without pre-drilled holes.
Munro praised some aspects, like the flow-drill fasteners and centralized bus bar design, but overall, the teardown suggested many elements could be streamlined or replaced entirely.
Where Weight Reduction Can Begin
Switching to a polymer-based or composite solution offers multiple avenues for savings:
- Eliminating fasteners: Bolts around the battery’s outer edge could be eliminated through molded-in features, potentially saving around 1 kilogram.
- Redesigning the battery base: Replacing the heavy aluminum base with a high-strength composite could cut significant weight.
- Integrating parts: Injection-molding connector housings and structural ribs into a single composite structure would reduce parts count and simplify assembly.
The original design incorporates aluminum extrusions with bolted-on nuts and anaerobic seals to prevent ingress. While effective, these solutions add weight and manufacturing steps. A molded polymer tray could replace multiple assemblies with one lightweight part, improving manufacturability and reducing leak points.
Crashworthiness Considerations
Safety can’t be compromised. Certain aluminum structures in the ID.4 battery pack are specifically designed for crash energy management — particularly in side and rear impacts.
However, composites like:
- Carbon fiber-reinforced polymers (CFRP)
- Heavy glass-fill composites
- Structural mats
can meet or exceed these crashworthiness requirements. With careful design, molded-in reinforcements could absorb and distribute crash loads, just as aluminum extrusions do today.
Potential Weight and Cost Savings
From the initial analysis, Munro believes a 25-kilogram reduction is easily achievable through composite redesign. This alone would equate to $250 in cost savings per vehicle — not including potential reductions in manufacturing time, tooling costs, or warranty claims thanks to fewer mechanical fasteners and simpler assembly.
In a best-case scenario, a full 50-kilogram reduction could be possible, matching the Tesla Model Y’s performance while maintaining the ID.4’s larger energy capacity.
Even partial gains would offer major advantages in a fiercely competitive EV market where every efficiency counts.
Thermal Management Strategies
One challenge in switching to composites is thermal management. EV batteries require careful cooling to maintain optimal operating temperatures.
The ID.4 likely uses a bottom-cooled architecture, although the teardown hadn’t yet revealed all details. To retain effective cooling, Munro suggests a hybrid solution:
- A composite enclosure for structural integrity and weight savings.
- A thin aluminum thermal plate integrated into the base for heat dissipation.
This hybrid approach would preserve critical cooling performance without negating the weight savings of switching to composites.
Engineering Takeaways
The Volkswagen ID.4 battery pack teardown uncovers valuable insights into lightweight design, cost-saving strategies, and manufacturing optimization. Among the most important findings are:
- Composite materials offer real opportunities for cost and weight reduction without sacrificing safety.
- Design integration — combining multiple parts into a single molded component — improves manufacturing efficiency.
- Fastener elimination strategies like molded-in connections and flow-drill technologies should be prioritized.
- Crashworthiness and thermal management must remain at the forefront of any redesign efforts.
As EV competition heats up, companies that aggressively pursue lean design and lightweight manufacturing will gain crucial advantages in cost, performance, and market appeal.
Final Thoughts
Munro’s teardown shows that Volkswagen has built a solid battery pack for the ID.4 — but there’s still considerable room for innovation. With the right material choices and smart design changes, the ID.4 platform could become even more competitive.
Companies like SABIC, one of the world’s largest polymer suppliers, see a clear opportunity to help automakers like Volkswagen move in this direction. If successful, collaborations like this could reshape how EV battery packs are designed and built in the future.
Interested in more teardown insights, lean engineering analysis, and the future of EV manufacturing?
Check out Munro’s expert breakdowns and stay ahead of the curve with the leaders in lean design.