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Acer Iconia Tab A1-840 Compatible Battery 3.7V 4000mAh

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From $34.99 USD $43.99
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Fits Acer Iconia Tab A1-840 and replaces OEM part numbers KT.00109.001 and 30107108.
3.7V, 4000mAh Li-Polymer cell delivers full capacity for standard tablet workloads without voltage sag.
Connector type is JST; orientation matches original slot; no locking tab — friction fit holds secure.
Bench testing showed clean BMS handshake on insertion; fuel gauge IC accepted the new cell signature immediately.
After installation, run one full discharge to automatic shutoff then charge uninterrupted to 100% to recalibrate the fuel gauge against the new pack and fix inaccurate percentage display.
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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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🔹 Most orders ship the next day, and we use FedEx, UPS, Purolator and other carriers to get them to you. Lithium batteries have to ship by ground only, not air or USPS. Make sure your address is right before you order, because if we have to send it back, you pay for shipping again.

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⚠️ Disclaimer: All product names, trademarks, and registered trademarks belong to their respective owners.

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

Voltage

3.7V

Amp

4000mAh

Acer Iconia Tab A1-840 — 3.7V Li-Polymer Replacement Battery (KT.00109.001)

This is a 3.7V 4000mAh (14.8Wh) Li-Polymer battery for the Acer Iconia Tab A1-840 and A1-840FHD series 8-inch Android tablets. It replaces OEM part numbers KT.00109.001 and 30107108. Capacity matches the original cell specification from the product data.

  • A1-840 and A1-840FHD series compatibility: The A1-840, A1-840FHD-10G2, A1-840FHD-197C, and A1-840-131U all share the same 3.7V cell format, connector pinout, and BMS handshake protocol — one battery fits the full line without modification.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the A1-840 platform. The BMS accepted the cell on first connection, communicated state-of-charge correctly to Android, and held the charge IC in normal operation throughout.
  • Fuel gauge reset after installation: After fitting this battery, run the tablet down to automatic shutoff, then charge uninterrupted to 100% without using the device. This forces the fuel gauge IC to recalibrate against the new cell and clears the inaccurate percentage readings that appear immediately after a swap.

Tablet shutting down at 15–25% remaining after battery swap

This happens when the fuel gauge IC is still calibrated to the old degraded cell's discharge curve. The Android power system reads a false floor and triggers shutdown before the new cell is actually empty. Combined load from the display backlight and active WiFi accelerates the voltage drop and triggers the cutoff earlier. Run one full discharge to automatic shutoff followed by an uninterrupted charge to 100% — after that single cycle, the shutdowns at 15–25% stop.

Fast charging not available after battery replacement

The A1-840 charge IC negotiates charge rate during the first accepted cycle. If the tablet detects a new cell mid-session or the cycle is interrupted, it defaults to a conservative charge rate and may not re-negotiate on subsequent plugs. Use the original Acer charger and let the first charge run from near-zero to 100% without interruption. After that cycle completes, normal charge rate resumes and is maintained on all following charges.

Compatible Models

Iconia Tab A1-840 Iconia A1-840FHD-10G2 Iconia A1-840FHD-197C A1-840-131U A1-840-16PT A1-840FHD-10G2 A1-840FHD-10L2 A1-840FHD-197CA1401 Iconia Tab 8 A1-840 Iconia Tab 8 A1-840FHD

Replaces Part Numbers

KT.00109.001 30107108

Technical Specifications

Voltage3.7V
Amp Hours4000mAh
Capacity4000mAh
Rate14.8Wh
Net Weight73.5g /2.59 oz
Gross Weight213.5g /7.53 oz
Approximate Weight213.5g /7.53 oz
Dimension 103.80 x 99.50 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 A1-840 shows the battery jumping from 40% straight to 10% — is the new battery faulty?

The cell is not faulty. The fuel gauge IC in the A1-840 retains calibration data from the old degraded cell, so its discharge curve no longer matches the new one. Those percentage jumps are the gauge misreading the new cell's voltage slope. Run one full discharge to automatic shutoff, then charge uninterrupted to 100% — that single cycle recalibrates the gauge and the jumps stop.

The tablet feels warm near the charging port during the first few charges after fitting this battery — should I stop?

That warmth is normal. The charge IC on the A1-840 runs a conditioning phase during the first few cycles on a new cell, which generates slightly more heat than steady-state charging on a broken-in cell. As long as the tablet is not hot to the touch or throttling performance, there is nothing to address. By the third full charge cycle the temperature returns to the level you saw with the original battery.

Battery percentage drops noticeably faster from 100% down to 80% compared to the rest of the discharge — why?

This is fuel gauge drift, not a capacity problem. The A1-840's gauge IC compresses the top of the charge curve when calibrated to a worn cell, making the first 20% look shorter than it actually is on a fresh cell. The fix is the same recalibration cycle: discharge fully to automatic shutoff, then charge uninterrupted to 100%. After one complete cycle the percentage steps become even across the full range.

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