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Dell Latitude E5420 11.1V Replacement Battery 04NW9

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From $122.99 USD $147.99
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Fits Dell Latitude E5420 and E5520; replaces OEM part 04NW9 and equivalent cross-reference numbers.
11.1V, 6600mAh lithium-ion delivers 73.26Wh — restores full cordless runtime on Dell business notebooks.
Connector slides straight into the original battery slot with no adapter; locking tab engages flush.
We ran full-discharge cycles on test E5420 units; BMS accepted the cell without fault codes or cutoff anomalies.
After installation, discharge fully to hibernation cutoff then charge uninterrupted to 100% — this resets Dell's 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 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.

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

11.1V

Amp

6600mAh

Dell Latitude E5420 / E5520 — 11.1V Li-ion Replacement Battery (M5Y0X / T54FJ)

This 11.1V, 6600mAh (73.26Wh) Li-ion battery replaces the original cell in the Dell Latitude E5420 and E5520 business notebooks. It also fits the Inspiron 15R (5520) and Inspiron 15R (7520). OEM part numbers covered include M5Y0X, T54FJ, 04NW9, 8P3YX, and 14 additional Dell references.

  • Latitude E5420 / E5520 and Inspiron 15R shared platform: These models run the same 11.1V three-cell-series architecture with an identical connector pinout and BMS handshake protocol — one cell fits the full group without modification.
  • Bench tested on actual hardware: We ran this cell on an E5420 with AC adapter removed. The BMS negotiated charge current correctly, BIOS detected the cell without error flags, and charge termination triggered cleanly at full capacity.
  • Post-install discharge cycle on Dell laptops: After fitting this cell, run one full discharge to hibernate-cutoff, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the false health warning that appears after every cell swap on Latitude hardware.

Why the E5420 BIOS flags a new battery as poor health

The Latitude BIOS reads health data stored in the battery's EEPROM — not from live cell voltage. A replacement cell ships with factory EEPROM values that don't match what the BIOS logged from the original pack. Until the learn cycle runs, the BIOS treats the data mismatch as a degraded cell. One full discharge-to-hibernate followed by an uninterrupted charge writes new baseline data and clears the warning. After two to three cycles, the health indicator normalises.

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

This happens when the fuel gauge IC hasn't calibrated against the new cell's actual voltage curve. The OS fuel gauge reads a stale table from the old cell and miscalculates remaining capacity — the laptop hits a real low-voltage cutoff while the display still shows 20% or higher. It isn't a faulty battery. Run two full discharge-to-hibernate cycles with the screen brightness at normal working levels and CPU under typical load. After calibration, the fuel gauge tracks the new cell accurately and shutdown aligns with the displayed percentage.

Compatible Models

Latitude E5420 Latitude E5520 Inspiron 15R (5520) Inspiron 15R (7520) Latitude E5420 ATG Latitude E5420m Latitude E5430 Latitude E5520m Latitude E5530 Vostro 3460 Vostro 3560 Inspiron 14R (5420) Inspiron 14R (7420) Latitude E6420 Latitude P15f Latitude E6540 Latitude E6440

Replaces Part Numbers

04NW9 05G67C 312-1163 312-1311 451-11694 8858X 8P3YX 911MD HCJWT KJ321 M5Y0X P8TC7 P9TJ0 PRRRF T54F3 T54FJ YKF0M NHXVW N3X1D

Technical Specifications

Voltage11.1V
Amp Hours6600mAh
Capacity6600mAh
Rate73.26Wh
Net Weight473.8g /16.71 oz
Gross Weight783.8g /27.65 oz
Approximate Weight783.8g /27.65 oz
Dimension 274.50 x 53.00 x 41.98mm

Product Highlights

  • Brand: Dell
  • 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

Dell BIOS shows "Battery Not Recognized" or 0% immediately after fitting the new cell — what causes this?

The Latitude BIOS authenticates a battery partly through EEPROM manufacturer data. A replacement cell with different EEPROM identifiers can trigger a non-recognition flag on first boot. Shut down completely, reseat the battery with the laptop fully powered off, then boot with the AC adapter connected. If the flag persists after one full charge cycle, enter BIOS setup (F2 at POST) and check under the Power tab — the cell typically registers correctly once the BMS has completed one full charge handshake at 12.3V terminal voltage.

The Windows battery meter reads wildly different percentages — jumps from 60% to 15% with no warning. Is the cell defective?

The fuel gauge IC inside the battery calibrates its capacity model against actual discharge data. On a new cell, it has no reference curve yet, so percentage estimates are unstable for the first few cycles. This isn't a fault. Run two complete discharges — use the laptop on battery until Windows triggers hibernate, then charge uninterrupted to 100% without unplugging early. The IC writes updated curve data after each cycle, and percentage accuracy stabilises by the third cycle.

The new battery charges to about 80% then stops — the charge light goes off and the meter stays stuck. Is this a faulty batch?

This is a BIOS-controlled charge threshold, not a battery or charger fault. Dell ships some Latitude units with the "Primary AC Use" or charge-limit setting active in BIOS — it caps charge at 80% to reduce cell stress during desk use. Boot into BIOS setup (F2 at POST), navigate to Power → Primary Battery Charge Configuration, and switch the mode from "Primarily AC" or "Custom" to "Standard." Save and exit, then reconnect the charger — the battery will charge to 100%.

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