About this replacement
Acer Iconia One 8 B1-850 — 3.8V Li-Polymer Replacement Battery (PR-2874E9G)
The PR-2874E9G is a 3.8V, 4500mAh Li-Polymer battery for the Acer Iconia One 8 B1-850 8-inch Android tablet. It also fits the A6001 and B1-850-K35X variants that share the same battery bay and connector spec. Capacity is 17.1Wh, matching the original cell specification.
- B1-850, A6001, and B1-850-K35X compatibility: These three models share the same PCB layout, connector pinout, and charge IC, so the same cell fits all three without modification or adapter.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the B1-850 and confirmed the BMS handshake completes correctly — the tablet accepted the battery without error flags or charge interruption.
- Fuel gauge recalibration after install: After fitting this battery, run one full discharge to automatic shutoff, then charge uninterrupted to 100%. This resets the fuel gauge IC against the new cell capacity and clears the inaccurate percentage readings that commonly appear after a swap.
Tablet shutting down at 15–25% remaining after battery swap
This is a voltage cliff issue, not a faulty battery. When the display backlight and WiFi radio draw current simultaneously, the cell voltage dips sharply under combined load. The system interprets that voltage dip as a critically low state and triggers an emergency shutdown before the percentage counter catches up. A full recalibration cycle — one complete discharge to shutoff followed by an uninterrupted charge to 100% — lets the fuel gauge IC map the new cell's voltage curve accurately and eliminates the early cutoff.
Fast charging not available after fitting a new battery
The B1-850's charge IC runs a USB-PD negotiation check on the first accepted charge cycle after a new cell is detected. Until that cycle completes, the tablet may fall back to standard 5V charging and show slower charge progress. Charge the tablet fully from near-empty using the original Acer adapter without interruption. After that first complete cycle, the fast charge protocol re-engages and the charge IC operates normally at the higher voltage rail.