About this replacement
Nvidia Shield K1 / P1761W — 3.8V Li-Polymer Replacement Battery (ST8)
This is a 3.8V, 4500mAh Li-Polymer cell that replaces the original ST8 battery in the Nvidia Shield Tablet K1 and Shield P1761W. The Shield K1 is a gaming-focused Android tablet released in 2015, and this battery matches the OEM voltage, capacity, and physical footprint at 153.50 × 73.80 × 5.00mm. Swap it in when the original cell no longer holds charge or shuts the tablet down early.
- Shield K1 and P1761W compatibility: Both models use the same ST8 cell on the same 3.8V power rail with an identical connector and BMS handshake profile. One battery covers both variants without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the Shield K1 board. The BMS accepted handshake on first connection, charge IC ramped normally, and no protection cutoff was triggered under gaming load.
- Fuel gauge recalibration after swap: After fitting this battery, run the tablet down to automatic shutoff, then charge uninterrupted to 100% without unplugging. This forces the fuel gauge IC to recalibrate against the new cell and clears the inaccurate percentage readings that appear after any battery replacement.
Shield K1 shutting down between 15–25% remaining after battery swap
The fuel gauge IC on the Shield K1 retains calibration data from the old cell. When a new cell is installed, the IC's voltage-to-percentage map no longer matches the new cell's actual discharge curve. Under combined display-plus-WiFi load, voltage sags faster than the IC expects, triggering a low-voltage protection cutoff that the OS reads as a sudden shutdown. One full discharge-to-cutoff followed by an uninterrupted charge to 100% resets this calibration and stops the early shutdowns.
Fast charging unavailable on the Shield K1 after fitting a new battery
The Shield K1's charge controller negotiates charge rate on the first accepted cycle after a new cell is detected. Until that cycle completes, the controller defaults to a conservative current limit and fast charge is not offered. Plug into the original Nvidia charger — not a third-party cable — and let the first charge run from near-zero to 100% without interruption. After that cycle finishes, fast charging resumes at the correct rate.