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Lenovo Flex 2 15" Replacement Battery L13M4A61 7.4V 4400mAh

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From $97.99 USD $116.99
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Fits Lenovo Flex 2 15", Flex 2 14", and related models; replaces L13M4A61, L13S4A61, L13L4A61, L13L4E61, and 121500262.
7.4V, 4400mAh capacity delivers 32.56Wh — sustains the touchscreen and CPU during convertible mode switching without voltage sag.
Connector plugs into the underside battery bay with a positive-ground keyed slot; locking tab secures the pack flush against the chassis.
We bench-tested this cell against a Flex 2 15" motherboard; the BMS reported full capacity on first charge with no cutoff anomalies.
On first boot after installation, run a full discharge to hibernation, then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears the inaccurate health warnings that appear after every cell swap.
Delivery time

This product ships directly from our Manufacturer's Warehouse and is usually delivered within 7 – 10 business days to your doorstep.

Discount: As a thank you for your patience, enjoy 5% off on your order
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Fresh Battery, Worth the Wait

To provide the highest-quality replacement battery, we ship this battery directly from the manufacturer rather than from aging warehouse inventory. This means delivery may take a little longer, but it helps ensure you receive a fresh battery with better performance, a longer lifespan, and greater reliability.

Estimated delivery: 7–10 business days
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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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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.

Voltage

7.4V

Amp

4400mAh

Lenovo Flex 2 15 — 7.4V Li-ion Replacement Battery (L13M4A61)

This is a 7.4V, 4400mAh (32.56Wh) Li-ion replacement battery for the Lenovo Flex 2 15" convertible laptop. It fits the Flex 2 14 and Flex 2 15 series, including both the 14" and 15" screen variants. OEM part numbers covered include L13M4A61, L13S4A61, L13L4A61, L13L4E61, and 121500262.

  • Flex 2 14 and 15 series compatibility: These models share the same 7.4V two-cell architecture, connector pinout, and BMS handshake protocol. One cell fits all variants in the Flex 2 range, from the standard 14 through to the 15" touchscreen 2-in-1 configuration.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on Flex 2 hardware. The BMS negotiated correctly with the Lenovo EC, accepted a full charge without tripping protection, and reported accurate state-of-charge data back to the OS fuel gauge within two cycles.
  • Post-install calibration on Flex 2: After fitting, run one full discharge to hibernate cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after every cell swap on Lenovo firmware.

BIOS reporting poor battery health after replacement on Flex 2

When you swap the cell in a Flex 2, the BIOS compares the new cell's EEPROM data against the stored charge history from the old battery. The mismatch triggers a false "poor health" or "replace battery" flag in Lenovo Vantage and the BIOS battery screen. This is not a fault with the new cell. Run one full discharge-to-hibernate cycle followed by an uninterrupted full charge — the BIOS learn cycle recalibrates against the new cell's actual capacity and clears the flag.

Flex 2 shutting down at 20–30% charge shown on screen

This happens when the cell voltage drops below the BMS cutoff threshold under combined CPU and display load, even though the OS fuel gauge still shows charge remaining. The fuel gauge IC reads state-of-charge from voltage curves calibrated to the old, degraded cell — so the reported percentage no longer reflects actual usable capacity. After fitting a new cell, the gauge needs two to three full discharge-and-charge cycles to re-map the voltage curve accurately. Once calibrated, the OS percentage and actual cell voltage will align, and the premature shutdowns stop.

Compatible Models

Flex 2 15" Flex 2 14 Flex 2 14" Flex 2 15 Flex 2-15 20405 Flex 2 14 20404 Flex 2 15D Flex 2 15-D 20377

Replaces Part Numbers

L13M4A61 L13S4A61 L13L4A61 121500262 L13L4E61 121500260 L13S4E61 L13S4E61(2INR19/66-2)

Technical Specifications

Voltage7.4V
Amp Hours4400mAh
Capacity4400mAh
Rate32.56Wh
Net Weight185g /6.53 oz
Gross Weight455g /16.05 oz
Approximate Weight455g /16.05 oz
Dimension 267.72 x 34.10 x 18.90mm

Product Highlights

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

Frequently Asked Questions

Lenovo Vantage shows the new battery as "Unknown" or 0% right after I installed it — is the cell dead?

The cell is not dead. Lenovo's EC reads battery identity from the EEPROM on the cell, and when the stored profile doesn't match the system's charge history, Vantage throws an "Unknown" or 0% flag while it re-establishes communication. Boot into the BIOS battery screen first — if voltage is present there, the cell is working. Run one full discharge to hibernate cutoff, then charge uninterrupted to 100%, and Vantage will display the correct status after the learn cycle completes.

My Flex 2 battery charge is stopping at 80% and won't go higher — what's causing that?

Lenovo's firmware on several Flex 2 units includes a BIOS-controlled charge threshold that caps charging at 80% to reduce long-term cell stress — it is not a fault with the replacement cell. Check Lenovo Vantage under Battery Settings for a "Conservation Mode" or charge threshold toggle. Disable Conservation Mode, then plug in and allow a full charge cycle. The battery will charge to 100% once the firmware limit is lifted.

The Flex 2 fuel gauge is jumping around — showing 60%, then 45%, then back to 55% within minutes. What resets it?

The fuel gauge IC on the Flex 2 uses a voltage-to-capacity curve that was mapped to your old, degraded cell. A new cell with different internal resistance throws the IC's readings off until it re-learns the curve. This is not a BMS fault and does not indicate a bad replacement cell. Run two to three complete discharge cycles — drain to hibernate cutoff, then charge uninterrupted to 4.20V per cell (8.4V total pack) — and the gauge IC will stabilise against the new cell's actual curve.

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