Dell Latitude 3340 Replacement Battery 11.1V 4400mAh YFDF9

Dell Latitude 3340 / 3350 — 11.1V Li-ion Replacement Battery (YFDF9)

This is an 11.1V Li-ion replacement battery rated at 4400mAh (48.84Wh) for the Dell Latitude 3340 and Latitude 3350 series ultraportable business notebooks. It replaces OEM part numbers YFDF9, VDYR8, HGJW8, and related variants. It fits directly into the original bay and connects to the existing power management circuitry.

• Latitude 3340, 3350, and 13 Education compatibility: These models share the same 11.1V battery rail, physical connector pinout, and BMS handshake protocol — the same cell works across the entire platform without modification.
• Bench tested on actual hardware: We ran this cell on a Latitude 3340 and confirmed the BMS handshake initialised correctly, charge cycles completed without fault codes, and the SMBus communication reported accurate state-of-charge data to the OS.
• First-cycle discharge protocol for Latitude systems: After installing, run the laptop on battery until it hibernates at low charge, then charge uninterrupted to 100%. This resets the BIOS battery learn cycle and clears the inaccurate health warning that appears after a cell swap.

Why the Latitude 3340 reports poor battery health after a new cell is installed

The Latitude 3340 stores battery health data in EEPROM on the original cell. When a replacement cell arrives, that EEPROM data is either absent or mismatched against the new chemistry. The BIOS reads this stale data and flags the battery as degraded before it has run a single cycle. This is a firmware-level read issue, not a fault with the replacement cell. Running the full discharge-to-hibernate then uninterrupted charge sequence forces the BIOS to rewrite its battery learn table against the actual new cell.

Latitude 3340 shutting down at 20–30% charge remaining after battery swap

This happens because the fuel gauge IC is still calibrated to the old cell's discharge curve. The new cell hits a voltage cliff under combined CPU and display load at a point the gauge still maps to 20–30% remaining. The laptop interprets the voltage drop as an imminent cutoff and shuts down. Run two full discharge-to-hibernate cycles followed by uninterrupted charges to 100% — this gives the fuel gauge IC enough data to remap its curve to the new cell. After two cycles, shutdowns at partial charge should stop.