About this replacement
LG VX8000 — 3.7V Li-ion Replacement Battery (SBPP0008701)
This is a 3.7V, 1400mAh Li-ion replacement battery for the LG VX8000 and VX-8000 feature phone. It slots into the same battery bay as the original SBPP0008701 / SBPL0074001 cells. Use it when the original battery can no longer hold a charge through a normal day of calls and standby.
- VX8000 and VX-8000 fit: Both model designations use the same battery bay geometry, connector pinout, and 3.7V nominal rail. One cell fits both. The BMS handshake is identical across the two variants.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on the VX8000 platform. The onboard charge IC accepted the cell without error, and the BMS held voltage within spec throughout the discharge curve.
- Fuel gauge recalibration on first use: After installing this battery, run one complete discharge down to automatic shutoff, then charge uninterrupted to 100% before resuming normal use. The VX8000's fuel gauge IC was calibrated to the old cell's discharge curve — one full cycle resets it against the new cell so percentage readings stay accurate.
Why the VX8000 reports wrong battery percentage after a cell swap
The VX8000 uses a fuel gauge IC that tracks charge state by measuring cumulative current flow — a coulomb counter approach. When you swap in a new cell, the IC still holds the discharge curve profile it built up from the old, degraded battery. The new cell has a steeper, healthier voltage curve, so the IC misreads state-of-charge and shows inflated or deflated percentages. One full discharge-to-shutoff followed by an uninterrupted charge to 4.2V forces the IC to rebuild its curve against the new cell.
Sudden shutdown at 20–30% on the replacement cell
This happens when the cell voltage drops below the modem's minimum operating threshold under transmit load, even though the fuel gauge still reads 20–30%. It's a voltage cliff — the cell can hold a resting voltage that looks healthy, but collapses under the current spike of an active call or data burst. The fix is completing the fuel gauge recalibration cycle described above so the IC learns where the real voltage cliff sits on this cell. After one full cycle, the phone will shut down at a lower, more accurate percentage rather than cutting out mid-use.