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Lenovo IdeaPad B450 Replacement Battery 11.1V 4400mAh L09M6Y21

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From $99.99 USD $119.99
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Fits Lenovo IdeaPad B450, B450A, B450L notebooks replacing L09M6Y21 or L09S6Y21 OEM cells.
Voltage rated 11.1V, capacity 4400mAh delivers 48.84Wh for sustained CPU and display load cycles.
Connector type matches original slot; locking tab engages flush without force or repositioning needed.
We bench-tested this cell on a B450 motherboard — BMS accepted the new pack after one full discharge cycle with no voltage cliff behavior observed.
After installation, run one complete discharge to hibernation-cutoff then charge uninterrupted to 100% — this resets the BIOS battery learn cycle and clears inaccurate health warnings that appear after cell swaps on Lenovo platforms.
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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By continuing with your purchase, you acknowledge and agree to the estimated 7–10 business day delivery timeframe.
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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

11.1V

Amp

4400mAh

Lenovo IdeaPad B450 Series — 11.1V Li-ion Replacement Battery (L09M6Y21)

This is an 11.1V, 4400mAh (48.84Wh) Li-ion replacement battery for the Lenovo IdeaPad B450, B450A, and B450L laptops. It matches the OEM voltage and form factor of the original L09M6Y21 and L09S6Y21 cells. The connector and battery bay dimensions align with the 208 × 54 × 22mm slot on all three B450 variants.

  • B450, B450A, B450L compatibility: All three share the same battery bay dimensions, voltage rail, and BMS handshake protocol — the L09M6Y21 and L09S6Y21 part numbers cross-reference across the full B450 lineup without modification.
  • Bench tested on actual hardware: We cycled this cell on a B450 chassis and confirmed the BMS recognised the pack, accepted a full charge sequence, and reported current draw correctly under combined CPU and display load.
  • First-cycle reset on the B450: After installing, 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 typically appears after a cell swap on this platform.

Why the B450 shuts down at 20–30% remaining after a battery swap

The B450's fuel gauge IC builds a capacity map based on the previous cell's charge curves. When a new cell arrives with different internal resistance, the IC's existing map no longer matches real voltage behaviour. Under full CPU plus display load, voltage drops faster than the old map predicts, triggering an emergency cutoff well above true empty. Two to three full discharge-and-charge calibration cycles force the IC to rebuild its map against the new chemistry. After calibration, the shutoff threshold shifts back to an accurate low-battery point.

BIOS reporting the replacement cell as "Unknown" or 0% on first boot

The BIOS reads battery identity data from EEPROM fields written by the original cell — manufacturer ID, cycle count, and rated Wh. A fresh replacement cell carries factory-default EEPROM values the BIOS hasn't seen before, so it flags the pack as unrecognised. This is not a fault with the cell. Boot into Windows, let the Lenovo Energy Management or native Windows battery driver run one complete charge cycle, and the BIOS will register the pack correctly on the next cold boot. Confirm recognition by checking that voltage reads 11.1V and capacity populates in the Windows battery report.

Compatible Models

IdeaPad B450 IdeaPad B450A IdeaPad B450L

Replaces Part Numbers

L09M6Y21 L09S6Y21

Technical Specifications

Voltage11.1V
Amp Hours4400mAh
Capacity4400mAh
Rate48.84Wh
Net Weight310.2g /10.94 oz
Gross Weight460.2g /16.23 oz
Approximate Weight460.2g /16.23 oz
Dimension 208.00 x 54.00 x 22.00mm

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

The B450 fuel gauge jumped from 45% to 2% and shut down without warning — is the new battery faulty?

The fuel gauge IC inherited the old cell's capacity map and can't yet predict where the new cell's voltage will cliff under load. This causes sudden, inaccurate drops and early shutdowns. Run two full discharge cycles — drain to hibernate-cutoff, then charge uninterrupted to 100% each time. After the second cycle the IC recalibrates against the new chemistry and the gauge stabilises.

Windows shows the replacement battery's Wh rating as lower than the original spec — why doesn't it match 48.84Wh?

The Wh figure Windows displays is pulled from the EEPROM field on the cell, which holds the manufacturer's rated value at factory defaults. This can differ slightly from the actual measured capacity until the fuel gauge IC runs enough cycles to write an updated full-charge capacity figure. The discrepancy is a data reporting lag, not a capacity defect. After two to three full charge cycles, the reported Wh figure in the Windows battery report will converge toward the actual 48.84Wh rating.

New battery installed, BIOS health shows "Poor" immediately — does the B450 need a firmware update?

No firmware update is needed. The B450 BIOS reads health status from the cycle count and state-of-health fields in the cell's EEPROM, and a fresh cell arrives with factory-default values the BIOS interprets as degraded or mismatched. Run the BIOS battery learn cycle: discharge fully to hibernate-cutoff, then charge to 100% without interruption. On the next cold boot, the BIOS re-reads the EEPROM and the health warning clears.

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