Batteries for Smart Glasses.
Ultra-thin curved cells engineered for the AI smart-glasses temple — audio, camera and waveguide display frames.
Slim temples, AI compute, all-day runtime.
Smart glasses pushed battery engineering to a new edge. The cell has to fit inside a 5-7 mm temple, survive 800+ charge cycles, swallow AI inference bursts without sagging, never get warm against skin, and still feel like an everyday pair of glasses. We have shipped cells into category leaders' reference designs and challengers — from 150 mAh audio-only frames in the Meta Ray-Ban form factor to 380 mAh waveguide-display frames in the Even Realities G1 and Rokid AR Studio class.
Ultra-thin Li-Po pouch cells, shaped to the temple.
Down to 0.45 mm thickness with curved and stepped profiles that hug the inside of a temple. Our HV LCO chemistry at 4.48 V gives +8 to 12% volumetric energy density versus a standard 4.40 V cell — meaningful when every mAh in a 0.8 mm temple is hours of AI assistant time.
Every cell is screened for volumetric swelling under 500-cycle and 85 °C / 85% RH aging — the two failure modes that haunt hermetically-sealed eyewear. Capacity retention at C/200 must clear 92% before a lot ships.
Thermal-aware BMS for skin-contact frames.
Integrated fuel gauging with skin-contact temperature limiting. The BMS de-rates charging and clamps peak draw when the user is wearing the device, protecting both wearer comfort and cell chemistry — most overcharge-driven swelling happens specifically in the warm-and-charging regime above 50 °C, and AI inference bursts can spike a 0.6 mm cell several degrees in seconds.
Supports wireless-charging hinges, pogo-pin docks and the USB-C contact-pad interfaces used in most smart-glasses charging cases (Meta Ray-Ban, Bose Frames, Solos AirGo). CC/CV protocol with C/10 termination ships as standard for 800+ cycle life targets.
What we ship into smart glasses.
| Frame Type | Capacity (per temple) | Thickness | Weight | Cycle Life |
|---|---|---|---|---|
| Audio-only AI glasses (Meta Ray-Ban class) | 150 - 180 mAh | 0.6 - 0.9 mm | 2.5 - 4 g | 800+ |
| Audio + camera AI glasses | 200 - 280 mAh | 0.8 - 1.2 mm | 4 - 6 g | 800+ |
| Waveguide display smart glasses (Rokid / Even Realities class) | 280 - 380 mAh | 1.2 - 1.8 mm | 6 - 9 g | 800+ |
| Tethered AR overlay glasses (Xreal One class) | host-powered | — | — | — |
Brand names reference the form-factor class — Zufek does not claim direct supply to any specific OEM unless under signed NDA.
Six layers between the spec and the field.
Every smart-glasses cell that leaves our line passes the same six checkpoints, sized to the smallest format we make.
HV LCO 4.48 V chemistry
+8 to 12% volumetric density vs 4.40 V baseline. Tighter charge-voltage reference (±10 mV) protects against the high-voltage electrolyte breakdown that limits cycle life.
0.45 mm thickness floor
Single-layer electrode stack with 12 µm copper foil and 10 µm separator. Pouch + tab inert mass < 35% of total volume — close to the practical limit for a portable cell.
Swelling-screened
500-cycle, 85 °C / 85% RH aging on every new lot. Z-axis growth must stay under 9% or the lot fails QC. Catches the moisture-driven electrolyte decomposition that ruins sealed temples.
Skin-contact thermal BMS
Cell-internal NTC + PCB thermistor with 2 to 4 °C lag compensation. Charging throttle above 38 °C skin-side temperature; AI burst current clamp above 42 °C cell.
Low-temp variant
−20 °C low-temp electrolyte option for outdoor and ski-goggle adjacent frames. Capacity at −20 °C ≥ 80% of room temp; cold-charge inhibit below 0 °C prevents lithium plating.
EMI-hard tab routing
Tab placement and pouch-internal layout co-designed with the antenna engineer to keep cell loop area away from BLE / Wi-Fi 6 / UWB / 5G antennas. Reduces re-tuning iterations.
What smart-glasses teams ask before they commit.
How thin can a battery really go in a temple?
Production-volume Li-Po pouch cells are stable down to 0.45 mm with HV LCO chemistry. Below 0.4 mm the inert-layer ratio starts to dominate, so capacity per unit volume drops and cycle life shortens. We routinely ship 0.6 to 1.0 mm cells for audio AI glasses and 1.0 to 1.8 mm cells for waveguide display frames. Read our field guide on sub-millimetre cells for the manufacturing constraints.
What capacity do I need for an all-day AI assistant frame?
Audio-only frames (Meta Ray-Ban Display class) average 70-110 mW and clear 4 hours active use on 150-180 mAh per temple. Add camera + AI bursts (LLM calls, real-time translation) and you need 200-280 mAh. Waveguide display frames step up to 280-380 mAh per temple. We help operators tune for "real day" usage profiles, not lab averages.
How do you keep skin-contact temperature down?
Three layers: a graphite or copper foil heat-spreader bonded to the cell underside, a thermal-aware BMS that throttles charging above 38 °C skin-side, and a cell-internal NTC that catches the 2 to 4 °C lag between cell and PCB during fast charge or AI inference bursts. Most field complaints we have ever traced have been "warm temple during charging or video record" — fixable in firmware.
How long does swelling qualification take?
500 cycles at 85 °C / 85% RH typically runs 5 to 6 weeks per lot. We start it in parallel with IEC 62133-2 testing so it does not extend the program critical path. Cells fail acceptance if z-axis growth exceeds 9% — most cells we ship today land at 4 to 6%.
What certifications do I need to ship to the EU and US?
UN 38.3 globally for transport. IEC 62133-2:2017 + Amendment 1 for safety in use. CE Battery Regulation for the EU, FCC at device level for the US. A tier-1 OEM will also ask for the IEC 62133-2 forced-internal-short test (Amendment 1 clause 7.3.9). Total stack runs USD 25 to 35k and 14 to 16 weeks. See our UN 38.3 + IEC 62133 walkthrough.
Engineering deep-dives.
Designing an Ultra-Thin Battery for Smart Glasses
Mechanical, thermal and EMI trade-offs below 1 mm.
Read the deep-dive →HV LCO at 4.48 V — Density Gains
What the high-voltage cathode platform actually delivers at the pack.
Read more →Custom-Shaped Polymer Lithium
The platform underneath every curved smart-glasses cell we ship.
Explore the pillar →Building the next pair of AI smart glasses?
Send the temple cross-section — we will come back with the thickest cell that fits and the longest runtime it can give.
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