One pack, one fuse, two rails. A protected 3.7 V lithium polymer pack of 3000 to 5000 mAh, mounted center back on the belt so its mass sits over the spine. Charger and protection, USB-C charging in a few hours, an inline fuse on the main rail, a keyed connector, and a 5 V boost rail for the sonars and the radar. IEC 62133-2 and UN 38.3, the battery use and transport certifications, are required before any kit ships (docs/13), in hand at G0, not yet passed. The record names no 3.3 V rail: the logic supply for the grids, the IMU, the multiplexers, and the twenty drivers, its regulator and its current budget, is a design value to be measured. Runtime is to be measured, not assumed. Source: docs/09.
Decision: one central 3.7 V lithium polymer pack of 3000 to 5000 mAh, protected, mounted center back on the waist belt so its mass sits over the spine and does not pull the belt forward. Charger and protection (TP4056 class plus DW01 class, or an integrated PMIC), a 5 V boost rail for the sonars and radar, USB-C charging in a few hours. One pack, not per band cells.
Demo and wireless stations: the phase 1 demo and any wireless station run on a small protected cell of about 500 mAh (Adafruit 1578 class) with an MCP73831 charger, charge current kept low, and never charged while worn.
Runtime: a full waking day at typical duty, several hours at worst case with many motors near full amplitude. Both to be measured, not assumed.
Safety: overcharge, over discharge, and short circuit protection; cell and pack to IEC 62133-2; transport to UN 38.3; inline fuse on the main rail; keyed connector so polarity cannot be reversed.
Source: docs/09-power.md, the engineering record. Every number on this page is read from that file. If a fact is not in the record, it is measured on the bench, or it stays off this site.