DJI Osmo Action AB1 Replacement Battery 3.85V 1250mAh

DJI Osmo Action — 3.85V Li-ion Replacement Battery (AB1)

This is a 3.85V, 1250mAh Li-ion replacement cell for the DJI Osmo Action camera. It fits the Osmo Action body directly and matches the OEM part number AB1. Capacity is 4.81Wh — identical to the original cell specification.

• Osmo Action platform fit: The Osmo Action uses a single-cell Li-ion pack with a BMS handshake that checks voltage signature and connector polarity at boot. This cell matches both, so the camera body accepts it through the standard power-on sequence without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on an Osmo Action body. The BMS logged correct cell voltage at each reporting interval and did not flag a protection fault at any point during testing.
• First-cycle initialisation on the Osmo Action: Charge this cell fully inside the camera body or OEM charger before your first shoot. The Osmo Action maps its battery-remaining display to a discharge curve — one full charge cycle from within the camera body lets the BMS calibrate that curve correctly for accurate percentage readout.

Osmo Action showing dead battery icon on a replacement cell that still has charge

The Osmo Action reads cell voltage at boot and maps it to a preset discharge curve stored in the BMS. A new replacement cell that has partially self-discharged during storage may present a resting voltage the camera interprets as critically low. This is a voltage-threshold mismatch, not a dead cell. Place the battery in the OEM charger first and bring it to full charge — once it reads 4.35V at the terminals, the camera will boot and report correctly.

Battery percentage jumping or resetting erratically during recording

The Osmo Action's fuel gauge estimates remaining capacity by tracking voltage drop against its internal discharge curve. A new cell has a slightly different discharge profile than the aged OEM cell the curve was calibrated for — this causes the percentage counter to jump at voltage inflection points. The fix is one full charge-to-discharge cycle so the BMS can re-anchor its curve to the new cell's actual voltage behaviour. After that cycle, percentage readout stabilises and tracks linearly down from 100%.