Meta engineers 7mm ultra-narrow steel-can batteries for AI glasses

Meta published a technical deep-dive Tuesday on how its engineers developed batteries narrow enough to fit into the temple arms of smart glasses — as thin as 7mm, narrower than anything that existed before. Traditional pouch-cell batteries (the kind in phones and laptops) cannot be reshaped small enough without losing power delivery and failing under load. Meta's answer was to replace the wound jelly-roll electrode design of conventional steel-can cells with die-cut stacked layers, similar to wiring small resistors in parallel.

The stacked-layer approach dramatically lowers impedance, which is critical for peak power delivery. Smart glasses need to handle simultaneous demands — a user recording video while asking the AI a question — without brownouts. The new design avoids the performance regression that comes from trying to shrink traditional cells. Meta is now scaling the technology across its hardware portfolio: Ray-Ban Meta and Oakley Meta Vanguards ship with this technology, and the company is “democratizing” the battery design for other vendors to adopt.

For product architects designing wearables under power constraints, Meta's steel-can innovation is a reminder that form-factor breakthroughs often come from rethinking internal component geometry, not just packing existing parts more tightly. The glasses deliver over 8 hours of runtime per charge, with the case providing another 40 hours — a baseline that will reset expectations for all-day-plus wear.