NET10 Midnight 3.7V 1200mAh Replacement Battery Li-ion

NET10 Midnight — 3.7V Li-ion 1200mAh Replacement Battery

This is a 3.7V, 1200mAh Li-ion replacement battery for the NET10 Midnight smartphone. It fits directly into the Midnight and restores power when the original cell has degraded or failed. Capacity is 4.44Wh as shipped.

• NET10 Midnight compatibility: The Midnight uses a compact 49.00 x 47.80 x 5.50 mm cell with a 3.7V nominal rail. This replacement matches that footprint and voltage exactly, so the phone's charge IC and fuel gauge IC see the same cell profile the board expects.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Midnight's board. The BMS accepted the cell without a lockout trip, and the charge IC reached termination voltage cleanly with no error flags.
• Fuel gauge recalibration on first use: On first installation, disable fast charging if your charger supports it and run one complete discharge-charge cycle at standard rate. This lets the Midnight's fuel gauge IC map the new cell's discharge curve before the coulomb counter begins tracking state-of-charge accurately.

Why the Midnight reports wrong battery percentage after a cell swap

The Midnight's fuel gauge IC stores a learned discharge curve from the original cell. When a new cell goes in, that stored curve no longer matches the actual cell chemistry, so the IC reports incorrect percentages. The fix is one full discharge to auto-off, then a full charge without interruption. After that cycle, the coulomb counter resets its reference point against the new cell and percentage readings stabilise.

Sudden shutdown at 20–30% on the replacement cell

This happens when the modem radio or display pulls a high current burst and the cell voltage drops sharply under load — a voltage cliff the fuel gauge IC did not predict. The IC was still calibrated to the old cell's sag curve and did not anticipate the new cell's internal resistance profile. Run one complete discharge-charge cycle first, which lets the IC recalibrate its low-voltage cutoff threshold. If shutdowns continue after two full cycles, check that resting voltage measures at least 3.6V with a multimeter before reinstalling.