Dell Latitude E5400 Replacement Battery 11.1V 6600mAh KM668
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Dell Latitude E5400 Replacement Battery 11.1V 6600mAh KM668 - is backordered and will ship as soon as it is back in stock.
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Battery Care Tips
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
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
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🔹 We use these names, brands, or model numbers only for identification and compatibility purposes.
Dell Latitude E5400 Replacement Battery 11.1V 6600mAh KM668 - is backordered and will ship as soon as it is back in stock.
Voltage
11.1V
Amp
6600mAh
Dell Latitude E5400 / E5500 Series — 11.1V Li-ion Replacement Battery (KM668)
This is an 11.1V, 6600mAh (73.26Wh) lithium-ion battery for the Dell Latitude E5400, E5500, E5410, and E5510 series laptops. It cross-references a long list of Dell OEM part numbers including KM742, MT186, RM649, PW640, WU841, and 312-0762, among others. If your original battery has degraded or failed completely, this cell matches the voltage rail, connector, and BMS handshake requirements for these platforms.
- E5400 / E5500 / E5410 / E5510 platform fit: These four Latitude models share the same battery bay geometry, 11.1V three-cell rail, and SMBus BMS communication protocol — which is why a single part number family spans all of them. The connector pinout and latch clip are identical across the group.
- Bench tested on actual hardware: We ran this cell on an E5400 and E5510 unit. The BMS handshook correctly on first insertion, BIOS recognised the battery without prompts, and charge current ramped through the expected CC/CV stages without interruption at either end.
- First-cycle calibration after install: After fitting this battery, 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 Latitude hardware.
BIOS reporting battery health as poor immediately after replacement
Dell's BIOS stores charge-cycle count and health data in the old cell's EEPROM. When a new cell is installed, the BIOS reads no matching history and flags the battery as degraded or unknown — even though the cell is new. This is a firmware interpretation issue, not a battery fault. Run the full discharge-to-hibernate then uninterrupted charge cycle described above. After one or two complete cycles, the BIOS recalibrates and the health warning clears.
Laptop shuts 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 discharge curve. The gauge reports 25% remaining, but the cell voltage under combined CPU and display load has already dropped below the BMS cutoff threshold — the laptop interprets this as a hard shutdown event. It is not a defective battery. Complete two full discharge-to-hibernate and full-recharge cycles, and the fuel gauge IC will map the new cell's voltage curve accurately. After calibration, the reported percentage at shutdown should align with the actual cell voltage of approximately 10.5V.
Compatible Models
Replaces Part Numbers
Technical Specifications
Product Highlights
- Brand: Dell
- Manufacturer: CS
- Series: Standard
- Color: Silver Grey
- Product Type: Li-ion
- Battery Type: Li-ion
- Warranty: 12 Months
- Bulk Orders: sales@batteryweb.com
Frequently Asked Questions
Dell BIOS says "Consider replacing your battery" the moment I put in a new cell — is something wrong with it?
Nothing is wrong with the cell. Dell's BIOS carries over EEPROM health data from the previous battery, and when it finds no matching history on the new cell it flags a health warning immediately. Run one complete discharge to hibernate-cutoff, then charge uninterrupted to 100%. That resets the BIOS battery learn cycle and clears the warning within one or two cycles.
The battery gauge on my E5500 is jumping around wildly — it shows 60% one minute and 35% the next after I swapped the battery.
The fuel gauge IC on these Latitude models needs two or three full discharge-and-recharge cycles to map its calibration curve against the new cell's chemistry. Until that mapping is complete, the percentage readout is interpolating against the old cell's data and will behave erratically. Do not rely on the percentage for the first two cycles. After the second full charge to 100%, the gauge settles and tracks accurately.
System Information shows the wrong Wh rating for this battery — it says 56Wh but the spec is 73.26Wh. Is the cell underspec?
The Wh figure shown in Windows or Dell's diagnostics is pulled from the EEPROM on the cell itself, and some replacement cells carry the rated Wh of the base OEM configuration rather than the actual chemistry capacity of the installed unit. The physical cell capacity is 73.26Wh as specced. To verify actual capacity independently, run Dell's built-in battery report from an elevated command prompt: `powercfg /batteryreport` — the "Design Capacity" and "Full Charge Capacity" fields will reflect what the cell delivers under load after two calibration cycles.
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