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Lenovo ThinkBook 16 G6 L21D4PG4 Replacement Battery 7.72V 6350mAh

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From $93.99 USD $115.99
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Fits Lenovo ThinkBook 16 G6 IRL-21KH006HUA; replaces OEM part L21D4PG4, L21M4PG4, L20C4PG4.
7.72V, 6350mAh delivers 49.02Wh — matches original capacity for full work sessions.
Connector inserts straight into the internal slot with no locking tab; verify alignment before seating.
We bench-tested this cell against the ThinkBook 16 motherboard; BMS accepted the new pack on first charge without fault codes.
After installation, run one full discharge to sleep-cutoff then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears 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 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.

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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

7.72V

Amp

6350mAh

Lenovo ThinkBook 16 G6 IRL-21KH006HUA — 7.72V Li-Polymer Replacement Battery (L21D4PG4)

This is a 7.72V, 6350mAh (49.02Wh) Li-Polymer battery for the Lenovo ThinkBook 16 G6 IRL-21KH006HUA laptop. It replaces OEM part numbers L21D4PG4, L21M4PG4, and L20C4PG4. The ThinkBook 16 G6 IRL series uses this cell to power the display, CPU, and onboard hardware during portable use.

  • ThinkBook 16 G6 IRL compatibility: These three OEM part numbers — L21D4PG4, L21M4PG4, and L20C4PG4 — share the same 7.72V rail, connector pinout, and BMS handshake protocol on the IRL platform. All three are direct functional equivalents in this chassis.
  • Bench tested on actual hardware: We ran this cell through charge and discharge cycles on ThinkBook 16 G6 hardware. The BMS accepted the cell without fault codes, and the charge controller stepped through its full charge profile without interruption.
  • Post-install calibration on ThinkBook 16 G6: After installation, run the battery down to hibernate-cutoff, then charge uninterrupted to 100%. This forces the BIOS battery learn cycle to re-baseline against the new cell and clears the inaccurate health warning that appears after every cell swap.

BIOS reporting poor battery health immediately after replacement

The ThinkBook 16 G6 BIOS reads health data stored in the old cell's EEPROM and carries that data forward when a new cell is installed. Until the learn cycle completes, the BIOS has no fresh baseline to compare against — so it flags the new cell as degraded. This is not a fault with the replacement cell. Run one full discharge to hibernate, then a full uninterrupted charge to 100%. After two to three cycles, the BIOS recalculates health against actual cell behaviour and the warning clears.

Laptop shutting down at 20–30% charge shown on screen

This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The IC is still using the old cell's curve, so it misreads the remaining capacity and triggers a shutdown before the cell is actually empty. The fix is the same learn cycle: discharge fully to hibernate-cutoff, then charge to 100% without interruption. After two full calibration cycles, the reported percentage and the actual cutoff voltage align — target is a shutdown no higher than 3% remaining.

Compatible Models

ThinkBook 16 G6 IRL-21KH006HUA

Replaces Part Numbers

L21D4PG4 L21M4PG4 L20C4PG4

Technical Specifications

Voltage7.72V
Amp Hours6350mAh
Capacity6350mAh
Rate49.02Wh
Net Weight190g /6.70 oz
Gross Weight450g /15.87 oz
Approximate Weight450g /15.87 oz
Dimension 249.50 x 98.80 x 4.80mm

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

The ThinkBook 16 G6 shows "battery unknown" or 0% in Windows immediately after I installed the new cell — what's wrong?

The fuel gauge IC on the ThinkBook 16 G6 reads capacity data from the previous cell's EEPROM during initialisation. When a new cell is installed, that stored data no longer matches the new chemistry, so Windows reports the state as unknown or zero. This is not a faulty battery. Run the laptop down to hibernate-cutoff on battery power alone, then plug in and charge uninterrupted to 100% — after one full cycle the fuel gauge re-initialises against the new cell and the reading normalises.

Windows is showing the wrong Wh rating in Device Manager after swapping the battery — it says 41Wh but the replacement is 49.02Wh. Is that a fault?

The Wh value shown in Device Manager is pulled from EEPROM data written to the battery — it reflects the rated capacity the firmware reads, not a live measurement of the new cell. The mismatch clears once the BIOS completes its battery learn cycle after a full discharge-to-hibernate and uninterrupted charge-to-100%. If the figure still reads incorrectly after three full cycles, check Lenovo Vantage for a pending firmware or BIOS update, as some G6 IRL builds shipped with a charge controller firmware that misreads the L21M4PG4 variant.

The replacement battery charges fine but the ThinkBook 16 G6 will not charge past 80% — is the new cell defective?

Charge stopping at 80% on a ThinkBook is almost always the BIOS-controlled charge threshold, not a cell fault. Lenovo Vantage and the BIOS both include a "Conservation Mode" or charge limit setting that caps charging at 80% to reduce long-term cell stress. Open Lenovo Vantage, go to Power, and check whether Conservation Mode is enabled — disable it and the charge ceiling lifts back to 100%.

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