How Meta Engineered Ultra-Narrow Batteries for AI Glasses
Smart glasses require batteries that fit inside extremely narrow temple arms while powering cameras, speakers, AI processing, and displays. Meta addressed this limitation by developing ultra-narrow steel-can cells, including batteries as thin as 7 mm, with redesigned electrode structures and tighter manufacturing tolerances. The approach increased capacity and peak-power performance while enabling different configurations across successive generations of Meta’s wearables. ## Why Traditional Pouch Cells Fall Short - Common in phones and laptops, pouch cells are difficult to shrink and reshape. - Folding, manufacturing tolerances, and wasted internal volume are especially costly in glasses. - Small pouch cells may also struggle to deliver peak power when several features operate simultaneously, such as recording video while an AI model processes a request. - Smart glasses instead need rigid, precisely shaped batteries that use nearly every available micron. ## Designing Ultra-Narrow Steel-Can Cells - Steel-can batteries are established in products such as watches and power tools, but Meta needed unprecedented widths down to 7 mm. - Engineers replaced the conventional wound “jelly roll” electrode with die-cut, stacked layers. - This architecture reduces impedance, helping prevent power drops or brownouts during simultaneous high-demand tasks. - Steel cans maintain their shape to approximately 100 microns, preserving usable space and improving energy density in narrow cells. ## Increasing Capacity Through System Design - The second-generation Ray-Ban Meta battery increased from 160 mAh to 210 mAh, about a 30% capacity increase. - The glasses nevertheless claimed roughly twice the runtime because of broader hardware and software improvements. - Gains came from better power management, tighter firmware control, and a form factor that accommodated a larger cell. - This demonstrates that battery life depends on the entire system, not chemistry alone. ## Managing Multiple Batteries and Higher Power Demands - Oakley Meta Vanguards use one battery in each temple arm. - Although the cells are symmetrical, the electrical loads are not evenly distributed. - Engineers had to address cross-charging risks and coordinate battery sequencing during startup and shutdown. - Meta Ray-Ban Display glasses created a sustained power demand because the display draws energy continuously rather than in short bursts. - They use a 248 mAh steel-can cell, the largest in Meta’s lineup. ## Scaling the Technology - Meta’s narrow steel-can design could support other wearable form factors beyond smart glasses. - The company is working to scale production across multiple vendors and build a more resilient supply chain. - Developing these cells required coordination among electrical, mechanical, firmware, manufacturing, and global collaboration teams. Meta’s steel-can battery technology shows how wearable battery improvements come from rethinking both cell construction and overall device engineering. For future compact wearables, precisely shaped, low-impedance cells combined with system-level power optimization offer a practical path to longer runtime and more demanding features.
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