Sky Vega 6 BAT-7400M Replacement Battery 3.7V 2700mAh

Sky Vega 6 / IM-A860K — 3.7V Li-ion Replacement Battery (BAT-7400M)

This is a 3.7V, 2700mAh Li-ion replacement battery for the Sky Vega 6 and Vega N6 smartphones, including IM-A860K and A860S 4G variants. It slots into the original battery bay and connects to the same four-pin flex contact. Capacity figure is sourced from product data, not estimated.

• Vega 6 / N6 platform compatibility: The IM-A860K and A860S 4G share the same 3.7V battery bay geometry and four-pin BMS contact layout. BAT-7400M covers the full range because the charge IC and protection circuit requirements are identical across these variants — same voltage rail, same connector pitch, same BMS handshake protocol.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Vega 6 platform. The BMS accepted the charge IC handshake on the first cycle, protection thresholds triggered correctly at the low-voltage cutoff, and the coulomb counter tracked state-of-charge without prompting a fault flag.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-charge cycle at standard current. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before any high-current charge session pushes current into an uncalibrated state.

Sudden shutdown at 20–30% on the Vega 6 after a cell swap

A new cell has a slightly different voltage-to-capacity curve than the aged cell the fuel gauge IC originally calibrated against. When the phone hits the modem transmission burst or screen-on peak draw, cell voltage can sag below the protection threshold even though the OS still shows 20–30% remaining. The BMS reads that voltage sag as a fault and shuts the phone down to protect the cell. One full discharge-charge cycle at standard rate allows the coulomb counter to resync against the new cell's actual curve, eliminating premature shutdowns.

Phone not powering on after the replacement battery sat in storage

Li-ion cells self-discharge during storage. If the BAT-7400M has dropped below approximately 2.5V per cell, the BMS enters lockout mode and will not pass current to the device — the phone appears completely dead. Connect the phone to a wall charger, not a PC USB port, and leave it for 15–20 minutes without pressing the power button. The charge IC delivers a low-current pre-charge trickle that brings the cell back above the BMS re-enable threshold, typically around 2.9V, at which point normal charging resumes.