About this replacement
Amazon Kindle Fire HD 8 5th Generation — 3.7V Li-Polymer Replacement Battery (ST11)
This 3.7V, 3210mAh lithium-polymer battery replaces the original ST11 cell in the Amazon Kindle Fire HD 8 5th Generation (model SG98EG). It fits the 8-inch tablet used for reading, streaming, and everyday app use. OEM part numbers ST11, ST11A, 58-000127, 26S1009, and 26S1009-A are all covered by this single replacement cell.
- Kindle Fire HD 8 5th Gen compatibility: The SG98EG shares a single battery platform across the 5th Generation HD 8 lineup. The ST11 connector pinout and BMS handshake are identical across all SG98EG units — one cell fits the full production run without any modification.
- Bench tested on actual hardware: We ran this cell on a Kindle Fire HD 8 5th Gen unit and confirmed the BMS accepted the new cell without fault codes, completed a full charge cycle without thermal cutoff, and reported voltage correctly at both ends of the discharge curve.
- Fuel gauge recalibration after swap: After installing this battery, run the tablet down to automatic shutoff, then charge it uninterrupted to 100% without using the device. This lets the fuel gauge IC recalibrate against the new cell and clears the inaccurate percentage readings that typically appear in the first few cycles after a swap.
Kindle Fire HD 8 shutting down at 15–25% after battery replacement
The Kindle Fire HD 8 combines display backlight, WiFi radio, and processor load simultaneously during streaming or browsing. That combined draw creates a sharp voltage sag that the fuel gauge IC misreads as a low-battery cutoff — even when meaningful charge remains. The original fuel gauge calibration was mapped to the old, degraded cell, so its voltage curve no longer matches the new battery. Run one full discharge to automatic shutoff followed by an uninterrupted charge to 100%, and the shutdowns at 15–25% will stop. After that cycle, the device should hold voltage above 3.5V well into single-digit percentages.
Fast charging not available on Kindle Fire HD 8 after battery swap
The Kindle Fire HD 8 uses Amazon's proprietary charge negotiation over the micro-USB port — the charge IC needs one completed charge cycle on the new cell before it will negotiate the higher current draw. Plugging in immediately after installation often results in standard 5V/1A charging only. Use the original Amazon power adapter, not a third-party charger, and allow the first charge cycle to complete fully without interruption. After that cycle, the adapter and charge IC handshake correctly and faster charging resumes at the expected rate.