LG 5300 BSL-51G Replacement Battery 3.7V 900mAh

LG 5300 / 5350 / G5300 — 3.7V Li-ion Replacement Battery (BSL-51G)

This is a 3.7V, 900mAh Li-ion replacement battery for the LG 5300, 5350, and G5300 mobile phones. It matches the OEM part number BSL-51G and fits the original battery bay without modification. Install it when the existing cell no longer holds adequate charge or has failed entirely.

• 5300 / 5350 / G5300 platform compatibility: These three models share the same battery bay dimensions, connector pinout, and BMS handshake protocol — all are served by a single BSL-51G cell rated at 3.7V nominal. The 64.12 × 42.50 × 8.56mm footprint seats flush in each variant.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the 5300 platform. The BMS accepted the cell without fault codes, the charge IC stepped through pre-charge, constant-current, and constant-voltage phases cleanly, and the fuel gauge IC registered capacity without error flags.
• Fuel gauge recalibration on first use: After fitting this cell, run one full discharge-charge cycle with fast charging disabled. The fuel gauge IC on the LG 5300 carries the old cell's discharge curve in memory — until it tracks a full cycle on the new cell, percentage readings can drift or jump erratically.

Sudden shutdown at 20–30% on the LG 5300 after a cell swap

This happens because the fuel gauge IC still holds the discharge curve of the degraded original cell. A fresh 900mAh cell has a steeper voltage slope in the lower charge window, so the phone's power management IC hits its cutoff voltage before the gauge catches up to the new curve. The modem and screen together pull enough current to cause a brief voltage sag — enough to trigger the cutoff even though capacity remains. One complete discharge-charge cycle, without fast charging, retrains the coulomb counter and moves the shutdown point back to the correct threshold near 3.0V per cell.

Phone warm near the battery compartment on the first few charges

A new Li-ion cell has slightly higher internal impedance than a broken-in cell — this is normal and drops off after the first few cycles. During that initial period, the charge IC pushes constant current into a higher-resistance cell, generating more heat than you'd see with the worn original. If the phone stays warm throughout the entire charge cycle and doesn't taper off, check that nothing is blocking ventilation around the rear cover. By the third full charge cycle, surface temperature during charging should return to normal operating range.