SK G588 Replacement Battery 3.7V 1500mAh Li-Polymer

SK G588 / GC588 — 3.7V Li-Polymer Replacement Battery

This is a 3.7V 1500mAh Li-Polymer replacement battery for the SK G588 and GC588 smartphones. It replaces the original cell when the phone no longer holds a charge, shuts down unexpectedly, or fails to power on. Capacity is 1500mAh (5.55Wh), matching the original specification.

• G588 and GC588 compatibility: Both models share the same battery form factor, voltage rail, and connector pinout. The BMS handshake protocol is identical across these two variants, so one cell fits both without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on compatible hardware. The BMS accepted the cell without fault flags, and charge termination triggered correctly at 4.2V with no thermal events during the test cycle.
• Fuel gauge recalibration after installation: On first use, disable fast charging and run one complete discharge down to automatic shutdown, then charge fully to 100%. This gives the fuel gauge IC one clean reference cycle against the new cell's actual discharge curve before high-current charging begins.

Why the G588 reports wrong battery percentage after a cell swap

The fuel gauge IC on the G588 uses a coulomb counter calibrated to the original cell's charge curve. When a new cell goes in, that stored curve no longer matches the actual cell behaviour. The phone reads state-of-charge against the old model, so percentages appear too high or too low until the IC relearns. One full discharge-to-shutdown followed by an uninterrupted charge to 100% resets the calibration.

Sudden shutdown at 20–30% on the replacement cell

This happens when the cell voltage drops sharply under high load — screen-on with mobile data active is the usual trigger. The protection circuit cuts output before the percentage display catches up, so the phone dies while showing charge remaining. The root cause is a voltage cliff: the cell cannot sustain the voltage threshold the system requires under peak current draw. Confirm the cell has completed at least one full recalibration cycle and check that the resting open-circuit voltage reads above 3.7V after a full charge.