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Acer Iconia One 8 B1-850 Compatible Battery PR-2874E9G 3.8V

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Fits Acer Iconia One 8 B1-850 and replaces OEM battery PR-2874E9G.
3.8V and 4500mAh rated for this 8-inch tablet's display and processor load.
Connector slides straight into the OEM slot without orientation issues or locking tabs.
We bench-tested this cell against the B1-850's fuel gauge IC; BMS accepted the handshake cleanly.
Run one full discharge to automatic shutoff then uninterrupted charge to 100% — this resets the fuel gauge calibration and eliminates the inaccurate percentage display that appears after a swap.
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Battery Care Tips

🔹 Getting Started

Charge your new battery fully before you use it for the first time. Over the next few charge cycles, run your device down to around 20% before you recharge—this helps the battery perform its best. After that, charge whenever you need to.

🔹 Keep It Healthy

Avoid letting your battery completely drain or staying plugged in constantly. Both extremes wear it out faster. Store the battery in a cool, dry place when you're not using it, since heat damages batteries quickly.

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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

3.8V

Amp

4500mAh

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.

Compatible Models

Iconia One 8 B1-850 A6001 B1-850-K35X

Replaces Part Numbers

PR-2874E9G

Technical Specifications

Voltage3.8V
Amp Hours4500mAh
Capacity4500mAh
Rate17.1Wh
Net Weight70.5g /2.49 oz
Gross Weight106g /3.74 oz
Approximate Weight106g /3.74 oz
Dimension 154.50 x 73.00 x 3.20mm

Product Highlights

  • Brand: Acer
  • Manufacturer: CS
  • Series: Standard
  • Color: Black
  • Product Type: Li-Polymer
  • Battery Type: Li-Polymer
  • Warranty: 12 Months
  • Bulk Orders: sales@batteryweb.com

Frequently Asked Questions

My Acer Iconia B1-850 says 60% battery but just shut off — is the new battery faulty?

The battery is not faulty. The fuel gauge IC in the tablet is still calibrated to the old cell's voltage curve, so the percentage reading and the actual cutoff point are out of sync. Run one full discharge to automatic shutoff, then charge uninterrupted to 100% without unplugging partway. That single cycle recalibrates the gauge and the shutdowns at high percentages stop.

The percentage is dropping from 100% to 70% in the first few minutes of use — what's wrong?

This is fuel gauge drift, not accelerated drain. The charge IC logged the old cell's degraded capacity as the baseline, so it miscalculates how fast the new cell is discharging. One complete cycle — full discharge to shutoff, then a full uninterrupted charge to 100% — resets the baseline to the new cell's 4500mAh capacity and the percentage drop normalises.

The tablet feels warm while charging after the battery replacement — should I be concerned?

Mild warmth during the first few charge cycles on a new Li-Polymer cell is normal. The charge IC runs a slightly higher current acceptance rate while it profiles the new cell, which generates more heat than a settled old cell would. If the tablet stays warm to the touch but not hot, let the cycle complete. If it becomes uncomfortably hot or the charge IC flags a warning in the battery settings, disconnect and check that the connector is fully seated at 3.8V with no bent pins.

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Acer Iconia One 8 B1-850 Replacement Battery, 3.8V, 4500mAh, Li-Polymer 1

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