Nexian NX-AC-001 Compatible Battery 3.7V 1200mAh Li-ion

Nexian NX-AC-001 / AC-001 — 3.7V Li-ion 1200mAh Replacement Battery

This is a 3.7V, 1200mAh Li-ion cell for the Nexian NX-AC-001 smartphone. It replaces the original battery when the cell can no longer hold a usable charge or causes unexpected shutdowns. The cell measures 60.00 × 43.80 × 4.50mm and fits the NX-AC-001 and AC-001 variants.

• NX-AC-001 and AC-001 compatibility: Both model designations reference the same handset platform — identical voltage rail, connector pitch, and PCB footprint. One cell fits both.
• Bench tested on actual hardware: We cycled the cell through full charge and discharge on the NX-AC-001 platform. The BMS accepted the replacement cell without fault flags, and the charge IC reached termination voltage cleanly.
• Fuel gauge recalibration after swap: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before committing coulomb counter data — skipping this step is the main cause of erratic percentage readings post-swap.

Sudden shutdown at 20–30% on the NX-AC-001 after a cell swap

A new cell has a slightly different voltage-versus-capacity curve than the worn cell the fuel gauge IC was calibrated to. When the phone's modem or display pulls a current spike, the new cell's terminal voltage can dip below the hardware cutoff threshold — even though the OS is still reporting 20–30% remaining. The phone shuts down not because the cell is empty, but because the fuel gauge IC is reading from the wrong curve. One full discharge-charge cycle without fast charging recalibrates the coulomb counter and eliminates the early cutoff in most cases.

Phone won't power on after the replacement battery sat in storage

Li-ion cells self-discharge in storage. If the replacement cell dropped below approximately 2.5V per cell before installation, the BMS enters lockout mode and blocks current flow to protect the cell from further damage. The phone will show no response — no charging indicator, no boot. Connect the phone to a wall charger, not a USB port, and leave it for 20–30 minutes without pressing the power button; the charge IC needs to trickle-charge the cell back above the BMS re-enable threshold of around 2.7V before normal charging resumes.