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L19D1P31 Lenovo Tab M8 Replacement Battery 3.85V 4900mAh

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From $30.99 USD $38.99
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Fits Lenovo Tab M8 TB8505F tablet and replaces OEM part L19D1P31.
3.85V, 4900mAh lithium-polymer cell restores full charge cycles to the M8 after original capacity fade.
Connector seats flat against the internal header with no locking tab — orientation matters on insertion.
Bench test showed clean BMS handshake on first charge cycle with no early cutoff or thermal spike.
After installation, run one full discharge to automatic shutoff then charge uninterrupted to 100% — this resets the fuel gauge IC calibration and resolves 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.

Delivery and Shipping

🔹 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.

Disclaimer

⚠️ 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

3.85V

Amp

4900mAh

Lenovo Tab M8 TB8505F — 3.85V Li-Polymer Replacement Battery (L19D1P31)

This 3.85V, 4900mAh lithium-polymer battery replaces part number L19D1P31 in the Lenovo Tab M8 (TB8505F). It fits directly into the tablet's battery bay and connects to the existing flex cable and charge IC. Capacity is 4900mAh (18.87Wh), matching the original cell specification.

  • Tab M8 TB8505F fitment: The TB8505F uses a flat Li-Polymer cell at 3.85V nominal. The connector pinout and BMS handshake are specific to this board revision — swapping with a mismatched cell causes the charge IC to reject the battery or report erratic state-of-charge readings.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a TB8505F board. The BMS accepted the cell without error flags, charge IC communicated correctly, and state-of-charge reporting stabilised after one full calibration cycle.
  • Fuel gauge recalibration after swap: After installation, run the tablet down to automatic shutoff, then charge uninterrupted to 100% without unplugging. This resets the fuel gauge IC calibration against the new cell's actual capacity curve and clears the inaccurate percentage readings that commonly appear after a battery swap.

Tab M8 shutting down between 15–25% remaining

The TB8505F's shutdown threshold is triggered by voltage drop, not percentage. Under combined display and WiFi load, the cell voltage sags below the BMS cutoff before the fuel gauge reaches 0%. This is most common with a degraded original cell but can also appear after a swap if the fuel gauge IC hasn't been recalibrated to the new cell. Run one complete discharge-to-shutoff cycle followed by a full uninterrupted charge — this resets the low-voltage curve mapping and stops premature cutoff around the 3.5V mark.

Fast charging unavailable on the Tab M8 after battery replacement

The Tab M8 uses USB-PD negotiation to enable higher charge rates. After a battery swap, the charge IC may default to standard 5V/1A until it completes one accepted full charge cycle with the new cell. Plug into a USB-PD charger and allow the tablet to charge from below 10% to 100% without interruption. On the next charge session, the fast charge icon should reappear — if it doesn't, verify the charger outputs at least 5V/2A and the cable is USB-PD rated.

Compatible Models

Tab M8 TB8505F

Replaces Part Numbers

L19D1P31

Technical Specifications

Voltage3.85V
Amp Hours4900mAh
Capacity4900mAh
Rate18.87Wh
Net Weight68.2g /2.41 oz
Gross Weight103.2g /3.64 oz
Approximate Weight103.2g /3.64 oz
Dimension 115.54 x 97.50 x 2.50mm

Product Highlights

  • Brand: Lenovo
  • 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 Tab M8 is showing 60% battery but just shut off — why?

The fuel gauge IC on the TB8505F reports percentage based on voltage curves calibrated to the original cell. When the cell changes — through age or replacement — those curves no longer match, and the tablet hits the BMS low-voltage cutoff before the displayed percentage reaches zero. This is a calibration mismatch, not a faulty battery. Run the tablet down to automatic shutoff, then charge uninterrupted to 100% to re-sync the fuel gauge to the actual cell voltage range.

The battery percentage on my Tab M8 is jumping around after I replaced the battery — is that normal?

Yes — it's expected after a swap. The fuel gauge IC retains calibration data from the old cell, so it misreads the new cell's state-of-charge, causing percentage jumps, sudden drops, or a reading that sits stuck for long stretches. One full discharge-to-shutoff cycle followed by a complete uninterrupted charge to 100% resets the calibration. After that single cycle, the percentage display should track steadily.

Fast charging stopped working on my Tab M8 after I swapped the battery — what happened?

The Tab M8's USB-PD negotiation depends on the charge IC completing one full accepted cycle with the new cell before enabling higher charge rates. Until that happens, the controller defaults to standard 5V/1A input. Connect a USB-PD rated charger and cable, then charge from below 10% to 100% without unplugging mid-session. Fast charge availability should return on the following charge cycle.

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