Dell Latitude D420 Compatible Battery 11.1V 3600mAh

Dell Latitude D420 / D430 — 11.1V Li-ion Replacement Battery (312-0444)

This is an 11.1V, 3600mAh (39.96Wh) Li-ion battery for the Dell Latitude D420 and D430 ultraportable laptops. It replaces OEM part numbers 312-0444, 451-10366, GG428, JG172, and 312-0445. Fits the standard battery bay on both models with no physical modification.

• D420 and D430 compatibility: Both models share the same battery bay dimensions, connector pinout, and BMS handshake protocol. One cell works across both platforms because Dell kept the same power rail and SMBus communication spec between generations.
• Bench tested on actual hardware: We ran this cell on a D420 and confirmed the SMBus communication initialised correctly, the BIOS accepted the battery as a valid source, and the charge controller reached full charge without throttling or fault codes.
• Post-install discharge cycle on the D420/D430: After installing, run one full discharge to the 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 these models.

Why the D420 BIOS reports poor battery health immediately after a cell swap

The D420 stores battery health data in the EEPROM of the original cell. When you swap in a new battery, that EEPROM data is gone and the BIOS treats the new cell as degraded until it gathers fresh cycle data. This is a firmware behaviour, not a fault with the replacement cell. Running a full discharge-to-hibernate followed by an uninterrupted charge gives the BIOS enough data to update its health estimate. After one or two cycles the warning clears and the health indicator reads accurately.

Laptop shuts down at 20–30% remaining on the D420

This happens when the fuel gauge IC has not yet calibrated against the new cell's actual voltage curve. The OS reads a percentage, but the underlying voltage under full CPU and display load drops below the cutoff threshold before the gauge reaches zero. The fix is a calibration cycle: let the laptop discharge fully under normal use until it hibernates, then charge to 100% without interruption. After two full cycles the gauge IC aligns with the cell and shutdowns at false percentages stop. If it persists past three cycles, check that the hibernate trigger voltage in power settings is not set below 10.8V.