Google Nexus G12 Replacement Battery 3.7V 1500mAh BA S530

Google Nexus One G12 / G15 — 3.7V Li-ion Replacement Battery (BA S530)

This is a 3.7V, 1500mAh Li-ion battery replacing part number BA S530 in the Google Nexus One G12 and G15. It powers the processor, display, radios, and all onboard functions. Capacity figures come from product data — 5.55Wh total energy.

• G12 and G15 shared cell platform: Both models draw from the same 3.7V single-cell architecture with an identical connector pinout and BMS handshake protocol. One cell covers both variants without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on a G12 unit. The BMS held cutoff at the correct high and low voltage thresholds, and charge termination triggered cleanly at 4.2V.
• Fuel gauge recalibration on first install: After fitting this cell, disable fast charging and run one complete discharge-to-charge cycle before normal use. This lets the fuel gauge IC map the new cell's discharge curve before any high-current charging pushes current into an uncalibrated state.

Why the Nexus One reports wrong battery percentage after a cell swap

The Nexus One uses a coulomb counter in the fuel gauge IC that was calibrated against the original cell's discharge curve. A new cell — even at the same nominal capacity — has a slightly different voltage-to-charge relationship. The IC reads the new cell against the old map, so percentage displayed can be off by 10–20% until it recalibrates. One full discharge from 100% down to auto-shutdown, followed by a full charge to 4.2V, resets the counter baseline.

Sudden shutdown at 20–30% remaining on the replacement cell

This happens when the modem transmit burst or screen backlight draws a current spike the cell cannot sustain without voltage dropping below the BMS cutoff threshold — even though the displayed percentage looks safe. The fuel gauge is reporting stored charge, not instantaneous voltage headroom. On a fresh cell this stabilises after two or three full cycles as internal resistance settles. If shutdowns persist past three full cycles, check that the battery connector is fully seated and measure resting voltage — it should read above 3.7V after a full charge.