LG VX9400 LGLP-AGHM Replacement Battery 3.7V 850mAh

LG VX9400 — 3.7V Li-ion Replacement Battery (LGLP-AGHM)

This is a 3.7V 850mAh Li-ion battery for the LG VX9400 slider phone. It fits the VX9400, VX-9400, and LG9400 variants. Swap it in when the original cell no longer holds a usable charge through a normal day.

• VX9400 platform fit: The VX9400, VX-9400, and LG9400 all share the same battery bay dimensions, connector pinout, and BMS handshake. This cell matches those specs at 70.83 × 48.18 × 5.97mm, so it seats without modification.
• Bench tested on actual hardware: We cycled this battery through charge and discharge on the VX9400 platform. The BMS accepted the cell without a protection trip, and the charge IC brought the cell to full capacity without thermal interruption.
• Fuel gauge recalibration on first cycle: After fitting this replacement, run one complete discharge to roughly 10% and then charge to 100% without interruption. The VX9400's fuel gauge IC was calibrated to the original cell's discharge curve — one full cycle resets that reference against the new cell so percentage readings stay accurate.

Sudden shutdown at 20–30% on the VX9400 after a cell swap

The VX9400's modem transmit bursts draw a short, sharp current spike. A new cell with a slightly different internal resistance curve can sag below the BMS cutoff threshold during that spike, even when the fuel gauge still shows charge remaining. This shows up as a hard power-off at 20–30% — not a gradual drain. One full discharge-charge cycle lets the fuel gauge IC map the actual voltage-capacity curve of the new cell, tightening the cutoff prediction. If shutdowns persist after two full cycles, check that the battery connector contacts are clean and fully seated.

VX9400 not powering on after the replacement battery sat in storage

Li-ion cells self-discharge in storage. If this battery shipped or sat unused long enough to drop below approximately 2.5V, the BMS enters a lockout state and blocks normal charging to prevent damage to a deeply discharged cell. The VX9400 will show no boot, no charge indicator, and no response. Connect the phone to a low-current USB charger — ideally 500mA — and leave it for 20–30 minutes without pressing any buttons. This allows the charge IC to trickle current past the BMS lockout threshold; once the cell climbs above 2.9V, the BMS releases and normal charging resumes.