Model the thermal limits, battery runtime, and speech latency of phoneless AI pendants (such as the Meta Muse Charm) across cellular uplinks, audio pipelines, and edge-versus-cloud compute splits.
| Stage | Subsystem | Time (ms) | Contribution |
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Unlike smartwatches that leverage Bluetooth Low Energy (BLE) proxying to your phone for all cloud traffic, standalone gadgets like the Meta Muse Charm must maintain independent cellular registration. This creates stringent hardware hurdles:
Cellular modems transmit up to +23 dBm (200 mW RF). With power-amplifier efficiencies near 30%, instantaneous current spikes hit 1.5A to 2.0A. For tiny 200–300 mAh cells, high internal resistance (ESR) causes voltage drops below the 3.2V PMIC cut-off unless supercapacitors or high-C rate cells are specified.
Under international standard IEC 62368-1, wearable surfaces resting against human skin cannot exceed 43°C sustained. With an 18 cm² pendant in a 25°C room, the maximum continuous heat dissipation before burning skin is strictly ~500 mW, requiring duty-cycling during heavy inference.
Human conversational latency is ~250–400 ms. A cellular connection adds 50–150 ms network RTT plus Opus packetization buffers. If time-to-first-token (TTFT) from the cloud model exceeds 500 ms, the total round-trip exceeds 1 second, breaking seamless conversational flow.