About this replacement
Amazon Kindle Oasis 3 — 3.8V Li-Polymer Replacement Battery (ST29 / 58-000252)
This 3.8V, 1100mAh Li-Polymer cell replaces the original battery in the Amazon Kindle Oasis 3 e-reader. It matches the OEM part numbers ST29 and 58-000252. Physical dimensions are 67.54 × 32.80 × 3.60mm — confirm against your existing cell before fitting.
- Kindle Oasis 3 fit: The Oasis 3 uses a slim Li-Polymer pouch cell on a 3.8V rail with a multi-pin connector that carries both power and BMS data back to the firmware. This cell matches that connector pinout and voltage rating exactly.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on an Oasis 3 unit. The BMS handshake completed without fault codes, and the device accepted a full charge cycle without dropping to error state.
- Post-swap charge cycle on the Oasis 3: After fitting, connect via USB-C and run one complete charge to 100% before use. The Oasis 3 firmware recalibrates its battery percentage display against a full charge cycle — skipping this step causes the gauge to read inaccurately from the first use.
Why the Oasis 3 shows an incorrect battery percentage after a cell swap
The Oasis 3 firmware tracks battery state using a coulomb counter that accumulates data on the original cell over time. When a new cell goes in, the counter still holds the old cell's history. Until the firmware runs through a complete charge-to-discharge cycle, the percentage reading will drift or jump. This is not a fault with the replacement cell — it is the firmware recalibrating. Run one full charge and at least one partial discharge before trusting the gauge.
Kindle Oasis 3 not powering on after battery replacement
Replacement Li-Polymer cells are shipped at storage voltage — typically around 3.6–3.7V — which can sit below the Oasis 3's minimum boot threshold. The device will appear completely dead even with the new cell installed. Connect the USB-C cable to a known working charger and leave it for at least 10 minutes without pressing any buttons. Once the cell clears the boot threshold, the charging screen will appear and the device will start normally.