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Electric vehicle engineering continues to evolve at a rapid pace, and the Hyundai Ioniq 5 exemplifies this trend with its thoughtfully engineered battery pack. In a detailed teardown conducted by Munro & Associates, key innovations—such as an integrated cold plate, simplified assembly, and cost-conscious material choices—emerge as central to Hyundai’s strategy. For automotive engineers, EV enthusiasts, and investors alike, the Ioniq 5 battery pack offers a case study in lean manufacturing and clever thermal management.
Integrated Cold Plate: A Structural Advantage
The Ioniq 5 battery design centers around an integrated cold plate. Instead of using modular cold plates like those in the Ford F-150 Lightning or Lucid Air, Hyundai embeds a stamped and brazed aluminum plate directly into the pack’s base. They friction stir weld the plate to the frame. Coolant flows through serpentine channels in the plate, efficiently managing thermal load. This approach simplifies structure while enhancing thermal performance.
This design eliminates redundant layering—no need for a separate cold plate bolted to a base sheet—and provides both weight savings and manufacturing efficiency. With all coolant ports external to the pack, the risk of internal leaks is minimized. This not only reduces failure modes but also streamlines the assembly process. Modules can be dropped in with minimal internal routing, simplifying both manufacturing and potential service operations.
Structural Cover and Impact Protection
The cold plate alone isn’t exposed to road debris. Hyundai covers it with an SMC (sheet molding compound) protective layer, secured with structural adhesives and fasteners. This adds an air gap for impact protection against stone impingement while preserving ground clearance—crucial in an underbody-mounted pack.
Additionally, the underside includes service access panels—an increasingly rare design feature—which allows easier maintenance of the BMS control board and a central ceramic fuse. While repairability is often questioned in EV packs, this shows Hyundai’s intentional lean toward serviceability.
Inside the Pack: Aluminum Extrusions and Manual Welds
Flipping the pack over reveals an aluminum extrusion-heavy construction—a technique shared by Ford and Volkswagen. Interestingly, Munro’s teardown found significant use of TIG welding, much of it appearing to be manual. This raises questions about Hyundai’s production scalability, especially since the EGMP platform underpins multiple high-volume vehicles.
Fastening strategies include rivet nuts embedded in the extrusions. While functional, these components add cost. Other OEMs like Volkswagen (ID.4) use flow-drill screws instead, reducing material and part complexity. The perimeter seal is a large injection-molded gasket with compression limiters, which, though costlier and labor-intensive, doubles as a venting strategy in case of thermal runaway.
Venting and Safety: Tradeoffs in Seal Technology
Instead of relying on external pressure relief valves alone, the Ioniq 5’s seal itself is designed to allow pressure to escape in thermal events. This approach, though more expensive and harder to assemble than liquid-applied gasketing (as used by Tesla), offers a balance between serviceability and safety. It’s a middle path—more robust than RTV but not as automated as liquid seals.
Thermal Interface Materials (TIM): Thick but Effective
One standout in the teardown was the generous use of thermal interface material. Approximately 10 kilograms of silicone-based TIM were used—about 3mm thick—between the module pouches and the cold plate. While this thick application ensures solid thermal contact and tolerance absorption, it adds considerable mass and cost.
Interestingly, raised bosses on the cold plate’s stamped surface likely necessitate this thicker TIM to maintain contact. It’s a functional compromise, possibly made to preserve ground clearance without flattening the cold plate entirely. The downside? A thicker TIM layer reduces heat transfer efficiency, countering some of the benefits of direct cooling.
Module and Cell Architecture
The Ioniq 5 pack contains 32 modules, each rated at 2P6S—totaling 12 pouch cells per module. This compact configuration allows for four modules per array across multiple segments in the pack. Compared to Ford’s Lightning or GM’s Ultium platform, Hyundai’s modules are smaller and easier to remove, thanks to the absence of internal coolant lines.
Each module features cross-hatched terminal overlays that allow single-bolt fastening between side-by-side modules. This design reduces part count, simplifies manufacturing, and aids in serviceability. The module housing uses steel side plates and a polymer top for safety and thermal management.
Cells utilize a Z-fold stacking method—where the separator is folded continuously, unlike the Hummer’s pancake-style stacking. The benefit? A more compact cell construction with roughly 10% lower cost per kWh, due to fewer discrete parts and more streamlined production.
BMS and Bus Bar Design
The battery management strategy includes eight cartridge-style Mobis BMS units located along a central spine extrusion. These units collect temperature and voltage data from each module array and connect to the central BMS controller. Hyundai’s architecture supports configurability—extended or standard range versions can add or remove modules and BMS units modularly, enhancing production flexibility.
Copper bus bars are used throughout, though this choice appears driven by reliability more than cost. Industry leaders like Lucid have already adopted aluminum bus bars in their 800V architecture to reduce mass and expense. Hyundai may still be evaluating the long-term effects of aluminum’s thermal cycling behavior, which tends to relax clamp load more than copper—an important consideration in safety-critical joints.
Within each module array, Hyundai integrates fusible links into the central bus bar. These are visible for service checks and allow safe disconnection of individual module groups in case of overcurrent. This detail demonstrates thoughtful design for both diagnostics and safety.
Comparison with Other OEMs
Compared to Tesla’s liquid-applied sealants, the Ioniq 5’s injection molded gasket appears old-school but functionally multipurpose. Unlike GM’s Ultium packs with enclosed clamshell modules, Hyundai embeds its pouch cells directly into the TIM layer—closer to Mach-E’s approach but cleaner in execution. While Lucid’s full aluminum bus bars represent a next-gen design, Hyundai’s hybrid approach balances cost, serviceability, and safety.
Final Thoughts: A Balanced Design with Clever Tradeoffs
The Hyundai Ioniq 5 battery pack represents a thoughtful blend of engineering priorities—cost, performance, safety, and manufacturability. While not as radically integrated as some competitors, its cold plate execution stands out as an elegant, consolidated solution. Service access, scalable architecture, and standardized cells make this a solid design for volume production.
Munro & Associates’ teardown reveals how Hyundai is leveraging its E-GMP platform for long-term flexibility and global deployment. For engineers, suppliers, and investors watching the EV space, the Ioniq 5 battery pack offers a benchmark in smart compromise—one that balances thermal performance, lean design, and manufacturability in a real-world context.
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