About this replacement
LG Optimus P705 / P705g — 3.7V Li-ion Replacement Battery (BL-44JH)
This is a 3.7V Li-ion battery rated at 2900mAh (10.73Wh), replacing the OEM BL-44JH cell in the LG Optimus P705 and P705g smartphones. It fits the internal battery bay directly, using the same connector and contact layout as the original. Voltage and physical dimensions match the OEM spec: 65.00 × 43.90 × 10.40mm.
- P705 and P705g compatibility: Both variants use the same BL-44JH footprint, voltage rail, and contact pinout. The BMS on each device handshakes with the same charge profile, so one cell covers both models without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the P705 platform, confirmed the BMS accepted the charge handshake on the first cycle, and verified the protection circuit tripped correctly at low-voltage cutoff.
- Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one full discharge-to-charge cycle before resuming normal use. This lets the fuel gauge IC map the new cell's discharge curve before the system starts making load-based predictions.
Why the P705 reports wrong battery percentage after a cell swap
The P705 uses a fuel gauge IC that tracks charge state using a coulomb counter calibrated to the original cell's internal resistance and discharge curve. When you install a new cell, the IC still references the old curve, so percentage readings drift — often reading high, then dropping suddenly. One complete discharge cycle down to automatic shutdown, followed by a full uninterrupted charge, forces the IC to rebuild its reference map against the new cell. After that cycle, readings stabilise and the gauge tracks accurately.
Sudden shutdown at 20–30% on the replacement cell
This happens when the fuel gauge IC has not yet recalibrated and the phone hits a load spike — screen brightness, modem transmission, or GPS — that pulls the cell voltage below the BMS cutoff threshold faster than the gauge predicts. The cell voltage collapses under load even though the reported percentage still looks safe. It is not a defective battery. Run the phone down to forced shutdown, charge fully to 100% without interruption, and the gauge recalibrates its low-voltage prediction point. After one full cycle the shutdowns stop.