Qiku QK-393 360 N4 Replacement Battery 3.85V 3000mAh

Qiku 360 N4 Series — 3.85V Li-Polymer Replacement Battery (QK-393)

The QK-393 is a 3.85V, 3000mAh lithium-polymer cell for the Qiku 360 N4 and 360 N4 LTE Dual SIM (model codes 1503-A01 and 1503-A02). It slots in when the original cell has degraded to the point of sudden shutdowns, erratic percentage readings, or inability to hold charge. Capacity is rated at 11.55Wh, matching the original specification.

• 360 N4 and N4 LTE Dual SIM compatibility: Both variants share the same battery bay dimensions, connector pinout, and BMS handshake protocol. The 1503-A01 and 1503-A02 board revisions pull from the same voltage rail, so one cell covers all four listed models without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the N4 platform. The BMS accepted full charge termination correctly, voltage held stable under simultaneous LTE and display load, and the protection circuit tripped at the expected low-voltage threshold without requiring a manual reset.
• Fuel gauge recalibration after installation: On first use after fitting this cell, disable fast charging and run one complete discharge down to automatic shutdown, then charge uninterrupted to 100%. This gives the fuel gauge IC one full cycle to map the new cell's discharge curve before fast-charge current is applied to an uncalibrated cell.

Sudden shutdown at 20–30% on the 360 N4 after a cell swap

The 360 N4's fuel gauge IC retains the discharge curve from the old, degraded cell after a swap. The new cell has a steeper voltage-versus-capacity curve at lower states of charge. When the modem fires up for an LTE handshake or the screen brightness spikes, current draw pulls cell voltage below the BMS cutoff threshold — even though the gauge still shows 20–30% remaining. The fix is one full discharge-charge cycle with fast charging off, which forces the coulomb counter to resync against the actual cell curve. After that cycle, shutdowns at false-low percentages stop.

Phone feels warm near the battery during the first few charges

A fresh lithium-polymer cell has slightly higher internal impedance than a broken-in cell. On the first few charge cycles, the charge IC pushes current into a cell that hasn't yet settled its internal resistance, and that difference converts to heat. This is normal and typically resolves by the third full charge cycle. If warmth continues beyond that point, check that the charger output does not exceed 5V/2A — the N4's charge controller is not rated for higher-voltage fast-charge adapters from other Qiku models.