BoostMobile N9515 Replacement Battery 3.8V 2300mAh

BoostMobile N9515 / WARP SYNC — 3.8V Li-ion Replacement Battery

This 3.8V, 2300mAh Li-ion cell replaces the internal battery in the BoostMobile N9515 and WARP SYNC smartphones. It fits the internal battery compartment and connects via the original ribbon connector. Installation requires opening the rear housing to swap the cell.

• N9515 and WARP SYNC compatibility: Both devices share the same battery bay dimensions (72.90 × 53.60 × 4.70mm), voltage rail, and connector pinout. One cell fits both without modification or adapter.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on compatible hardware. The BMS accepted the charge handshake without tripping overcurrent protection, and voltage held stable under simultaneous screen and modem load.
• Fuel gauge recalibration on first use: After installation, disable fast charging and let the phone complete one full discharge down to automatic shutdown, then charge uninterrupted to 100%. This gives the fuel gauge IC one complete data set to map the new cell's discharge curve before fast-charge current is applied.

Sudden shutdown at 20–30% on the N9515 after a cell swap

The N9515's fuel gauge IC holds a discharge model built on the original cell. A new cell with different internal impedance hits a voltage cliff at a different state of charge than the old model expects. When the phone's modem or display pulls a current spike, the cell voltage briefly dips below the shutdown threshold — even though the coulomb counter still shows 20–30%. One full discharge-to-shutdown followed by an uninterrupted charge to 100% forces the IC to rewrite its model against the new cell. After that cycle, the shutdown threshold lines up correctly with actual remaining charge.

Battery percentage jumping erratically after replacement

Erratic percentage readings — jumping from 45% to 61% or dropping 10% in seconds — come from the fuel gauge IC trying to apply a stale calibration curve to a new cell. The coulomb counter loses sync when the cell's charge and discharge characteristics don't match the stored model. The fix is the same forced recalibration cycle: drain the phone to automatic shutdown, then charge straight to 100% without interruption. After two full cycles the percentage display stabilises to within a few percent of actual charge.