Dell Latitude 12 5000 Replacement Battery 11.1V 3400mAh

Dell Latitude 12 E5250 / E5270 Series — 11.1V Li-Polymer Replacement Battery (RYXXH)

This is an 11.1V, 3400mAh (37.74Wh) Li-Polymer battery for the Dell Latitude 12 5000, E5250, E5270, and E5550 series notebooks. It replaces OEM part RYXXH and its many cross-reference numbers including 451-BBUJ, 05TFCY, and NGGX5. Fit is confirmed by connector type, BMS handshake protocol, and Dell's EEPROM authentication routine.

• Latitude E5250 / E5270 / E5550 platform: These models share the same battery bay dimensions, 11.1V power rail, and Dell EC authentication sequence. A single cell variant covers the full range because the BMS reports capacity and cell chemistry identically across these chassis generations.
• Bench tested on actual hardware: We ran this cell on an E5250 chassis and confirmed the BMS completed full handshake, Dell's battery health status cleared from "Unknown" to active, and charge cycles initiated without BIOS intervention or authentication errors.
• Post-install recalibration on Dell EC firmware: After fitting this cell, run one full discharge to hibernate-cutoff, then charge uninterrupted to 100%. This resets Dell's BIOS battery learn cycle and clears the inaccurate health warning that appears on nearly every cell swap in this platform.

BIOS reporting battery health as "Poor" or "Unknown" after replacement

Dell's embedded controller reads EEPROM data from the installed cell and compares it against its stored charge history. When a new cell goes in, that history is blank or mismatched, so the EC flags the battery as degraded before it has run a single cycle. This is a firmware classification issue, not a physical fault. Run one full discharge-to-hibernate cycle followed by an uninterrupted charge to 100% — the EC rewrites its baseline and the health status clears.

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

The fuel gauge IC calibrates against the old cell's discharge curve stored in BIOS. When the new cell's voltage profile differs slightly, the IC predicts empty before the actual cell voltage drops to cutoff. Under combined CPU and display load, the voltage cliff arrives faster than the fuel gauge expects, triggering an emergency shutdown. Run two or three full discharge-to-recharge cycles — the fuel gauge IC recalibrates against the new cell's actual curve. After calibration, shutdowns below 15% indicated should stop entirely.