About this replacement
Amazon Kindle Fire 2019 9th Generation — 3.8V Li-Polymer Replacement Battery (MC-308695)
This 3.8V, 3000mAh lithium-polymer battery replaces the original cell in the Amazon Kindle Fire M8S26G and Kindle Fire 2019 9th Generation tablets. It matches the OEM part numbers MC-308695, 58-000255, and ST28. When the original cell no longer holds a charge or the tablet shuts down unexpectedly, this is the direct replacement cell for that board.
- Kindle Fire 9th Gen platform fit: The M8S26G and the 2019 9th Generation Kindle Fire share the same battery bay dimensions, connector pinout, and BMS handshake protocol. Both accept this 97.00 × 84.90 × 2.62mm cell without modification.
- Bench tested on actual hardware: We cycled this battery through charge and discharge on a Kindle Fire 9th Gen unit. The BMS accepted the cell on first connection, reported state-of-charge correctly after one full calibration cycle, and held voltage within spec across display and WiFi combined load.
- Fuel gauge IC reset after installation: After fitting this battery, run one full discharge to automatic shutoff, then charge uninterrupted to 100%. The Kindle's fuel gauge IC calibrates against the new cell during that first cycle. Skipping this step causes the percentage display to read inaccurately for days.
Kindle Fire 9th Gen shutting down at 15–25% remaining after a battery swap
This happens because the fuel gauge IC is still calibrated to the old cell's voltage curve. The new cell has a slightly different discharge profile, and the IC interprets a voltage dip under combined display and WiFi load as a critical low-battery condition. The tablet triggers a protective shutdown before the cell is actually depleted. One full discharge-to-shutoff followed by an uninterrupted charge to 100% resets the IC's reference points and resolves the premature cutoff.
Fast charging not available on the Kindle Fire after battery replacement
The Kindle Fire's charge IC uses a USB-PD negotiation handshake to enable faster charge rates. On a freshly installed cell, that handshake sometimes does not complete until the battery has accepted at least one full charge cycle. Use the original Amazon 9W adapter, not a third-party charger, for the first charge. After one complete cycle the charge IC re-negotiates correctly and faster charging resumes at the standard rate.