Verizon VS920 Replacement Battery BL-49KH 3.7V 1300mAh

Verizon VS920 Spectrum — 3.7V Li-ion Replacement Battery (BL-49KH)

This 3.7V, 1300mAh Li-ion cell is a direct replacement for the Verizon VS920 Spectrum and Spectrum 4G. It slots into the same battery bay as the original BL-49KH and restores power to phones where the original cell has degraded or stopped holding charge. Capacity is 1300mAh (4.81Wh), matching the factory specification.

• VS920 / Spectrum 4G compatibility: The Spectrum and Spectrum 4G share the same battery bay dimensions, connector pinout, and 3.7V voltage rail — one cell fits both. The BMS handshake on this replacement matches the original LG/Verizon charge controller so the phone accepts the cell without a fault flag.
• Bench tested on actual hardware: We cycled this cell on the VS920 platform and confirmed the BMS communicates correctly with the charge IC. The cell charges to 4.2V at termination and the protection circuit trips as expected on over-discharge below 3.0V.
• Fuel gauge recalibration on first install: On first use after installation, disable fast charging and run one full discharge-to-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before it locks in percentage readings — skipping this step causes erratic percentage jumps for the first several cycles.

Why the VS920 Spectrum shuts down suddenly at 20–30% after a cell swap

The Spectrum's fuel gauge IC retains the discharge curve from the old, degraded cell. When a fresh cell is installed, the IC still expects voltage to drop steeply at a point that corresponds to the old cell's worn-out floor. At around 3.55–3.60V under modem or screen load, the phone triggers a low-voltage shutdown even though the new cell has usable capacity remaining. One full calibration cycle — draining to auto-off and charging uninterrupted to 100% — rewrites the coulomb counter reference and eliminates the premature cutoff.

Phone reports wrong battery percentage after replacement

This is a fuel gauge IC calibration issue, not a defective cell. The coulomb counter was trained on the previous battery's internal resistance and capacity curve, so percentage readings on the new cell are off — sometimes by 15–25 points. Charge the phone to 100% without interruption, let it drain fully until it powers off on its own, then charge again to 100%. After that single complete cycle, the fuel gauge recalibrates to the new cell and percentage readings stabilise.