Amazfit A1929 Replacement Battery 3.85V 270mAh

Amazfit Stratos 3 / A1929 — 3.85V Li-Polymer Replacement Battery (PL322728H)

This is a 270mAh (1.04Wh) 3.85V lithium-polymer cell built to the PL322728H specification. It fits the Amazfit A1929 and Stratos 3 smartwatch platforms. Replace the original cell when the watch no longer holds a charge across a full day of use.

• A1929 and Stratos 3 compatibility: Both models run the same 3.85V power rail, share the PL322728H cell footprint (27.80 × 22.90 × 3.40mm), and use an identical connector and BMS handshake — a single cell spec covers both.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the Stratos 3 platform. The onboard BMS accepted the cell without fault flags, and the fuel gauge IC registered correctly after a full charge cycle from near-zero.
• Post-swap charge protocol for the Stratos 3: Place the watch on its magnetic charger immediately after fitting this cell and charge to 100% before first use. The fuel gauge IC on this platform loses its voltage reference during a cell swap and cannot recalibrate without a complete charge cycle from near-zero.

Why the Stratos 3 fuel gauge reads incorrectly after a cell swap

The Stratos 3 uses a coulomb-counting fuel gauge IC that tracks charge state relative to a stored reference voltage. Removing the cell wipes that reference. When a new cell is fitted at partial charge, the IC has no baseline, so it reports an arbitrary percentage — often 0% or a frozen value. A full charge cycle from near-zero writes a new reference and restores accurate reporting. Until that cycle completes, the displayed percentage is not reliable.

New battery draining in one day instead of the expected multi-day window

On the Stratos 3, continuous heart rate monitoring and always-on display mode together draw significantly more current than basic timekeeping. If both are active, a 270mAh cell will deplete far faster than the rated multi-day figure. Check the watch settings and disable continuous HR polling — switching to interval-based sampling (every 5 minutes) measurably reduces draw. GPS activity logging also pulls sustained current; disable background GPS if the watch is not actively recording a session.