About this replacement
Amazon Kindle Oasis — 3.7V Li-Polymer Replacement Battery (58-000117)
This is a 3.7V, 240mAh Li-Polymer replacement battery for the Amazon Kindle Oasis e-reader (models KO1, 223337, SW56RW and related variants). It fits the original cell slot and connects to the same BMS interface as the factory unit. Part number 58-000117 confirms the correct cell for this specific Kindle generation.
- Kindle Oasis KO1 and 223337 compatibility: These models share the same 3.7V cell footprint, connector pinout, and BMS communication protocol — the firmware reads charge state and temperature data from the same register set across all listed variants.
- Bench tested on actual hardware: We ran this cell through full charge and discharge cycles on the Kindle Oasis platform. The BMS accepted the cell without fault codes, and charge percentage reporting stabilised after one complete cycle.
- Post-swap charge cycle for Kindle Oasis: After installing, connect via the Kindle's USB cable and charge without interruption until the indicator confirms full charge. The Oasis firmware recalibrates its fuel gauge to the new cell during this first uninterrupted cycle — skipping it causes the percentage display to jump erratically.
Why the Kindle Oasis shows low battery immediately after a new cell
Replacement cells ship at storage voltage — typically 3.6V or below — not at a full 4.2V charge. The Kindle Oasis firmware reads this low resting voltage and flags it as a depleted battery before you even power on. This is not a cell defect. Connect to USB power immediately after installation and allow a full uninterrupted charge cycle before drawing any conclusions about capacity.
Battery percentage jumping around after the swap
The Oasis fuel gauge IC stores calibration data tied to the original cell's charge curve. When a new cell is installed, those stored values no longer match the actual charge state, so the displayed percentage reads inconsistently. The firmware recalibrates automatically, but only during a full charge-to-discharge cycle. Run one complete cycle — charge to 100%, use until the device prompts for charge — and the percentage display will stabilise at that point.