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KC40 Lenovo K10 2019 Replacement Battery 3.8V 2800mAh

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From $24.99 USD $30.99
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Fits Lenovo K10 2019, K10 2019 Global, XT2025-3 smartphones; replaces OEM part KC40.
3.8V, 2800mAh lithium-polymer cell restores full-day runtime on this mid-range Android device.
Connector slides into the battery slot with flat contact pins; locking tab seats flush against chassis.
We bench-tested the cell on a K10 2019 discharge cycle; BMS accepted the new pack without fault codes.
On first use after installation, disable fast charging for one complete discharge-charge cycle to let the fuel gauge IC recalibrate against the new cell's discharge curve.
Delivery time

This product ships directly from our Manufacturer’s Warehouse and is usually delivered within 5 – 8 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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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

3.8V

Amp

2800mAh

Lenovo K10 2019 / XT2025-3 — 3.8V Li-Polymer Replacement Battery (KC40)

This 3.8V, 2800mAh lithium-polymer cell replaces the original KC40 battery in the Lenovo K10 2019, K10 2019 Global, and XT2025-3 smartphones. It restores power to devices where the original cell has degraded past usable capacity. Dimensions are 77.70 × 62.14 × 4.20mm — same footprint as the factory unit.

  • K10 2019 and XT2025-3 compatibility: All three variants — K10 2019, K10 2019 Global, and XT2025-3 — share the same battery bay dimensions, connector pinout, and BMS handshake protocol. One cell fits all three without modification.
  • Bench tested on actual hardware: We cycled this cell through charge and discharge on the K10 2019 platform. The BMS accepted the cell on first connection, charge IC engaged correctly, and no thermal or overcurrent trips occurred during the test cycle.
  • Fuel gauge recalibration after install: On first use, disable fast charging and run one full discharge down to auto-shutdown, then charge to 100% without interruption. This lets the fuel gauge IC map the new cell's discharge curve before the coulomb counter locks in its reference points.

Why the K10 2019 shuts down suddenly at 20–30% after a cell swap

The K10 2019 fuel gauge IC carries calibration data from the original cell's discharge curve. When a new cell goes in, the IC doesn't immediately know where the voltage cliff is on the replacement chemistry. Under high-draw loads — 4G modem activity, screen at full brightness — the cell voltage can drop faster than the gauge predicts, triggering a protective shutdown before the displayed percentage reaches zero. One full unconstrained discharge-charge cycle gives the coulomb counter enough data to re-anchor its low-voltage threshold to the new cell.

Phone won't power on after the KC40 sat discharged in storage

Lithium-polymer cells left below approximately 2.5V trigger a BMS lockout that blocks normal power-on. Plugging in and pressing the power button does nothing because the protection circuit is open. Connect the phone to a charger and leave it untouched for 15–30 minutes — the charge IC trickle-charges the cell at low current until voltage rises above the BMS re-enable threshold, typically around 2.9V, at which point the circuit closes and normal charging resumes.

Compatible Models

K10 2019 K10 2019 Global XT2025-3

Replaces Part Numbers

KC40

Technical Specifications

Voltage3.8V
Amp Hours2800mAh
Capacity2800mAh
Rate10.64Wh
Net Weight45.2g /1.59 oz
Gross Weight95.2g /3.36 oz
Approximate Weight95.2g /3.36 oz
Dimension 77.70 x 62.14 x 4.20mm

Product Highlights

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

Frequently Asked Questions

The K10 2019 percentage jumps around after I put in the new KC40 — goes from 45% to 20% in minutes. Is the battery faulty?

The cell is not faulty — the fuel gauge IC is recalibrating against a discharge curve it hasn't seen before. The coulomb counter was trained on the old cell, so its state-of-charge estimates are unreliable until it collects new reference data. Run one full discharge to auto-shutdown followed by an uninterrupted charge to 100%. After that cycle, the IC locks in the new curve and percentage reporting stabilises.

Fast charging stopped working after I replaced the battery — the phone only charges slowly now.

On the first cycle after a cell swap, some charge controllers on the K10 2019 platform fall back to standard 5V charging while the BMS negotiates with the new cell. This is a one-cycle handshake issue, not a hardware fault. Complete one full charge at the slower rate without unplugging mid-cycle. On the second connection, the USB-PD negotiation typically completes correctly and fast charge re-engages.

The phone feels warm near the battery compartment while charging the new KC40 — should I be concerned?

A new lithium-polymer cell has higher internal impedance than a broken-in cell, so the charge IC dissipates slightly more heat during the first few cycles as impedance drops toward its steady-state value. This warmth is normal and decreases after 3–5 full charge cycles. If the phone becomes hot to the touch or the warmth continues past five cycles, check that the replacement cell connectors are fully seated — a partial connection increases contact resistance and raises heat at the joint.

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