Motorola JG40 Moto G7 Plus Replacement Battery 3.85V 2850mAh

Motorola Moto G7 Plus (JG40) — 3.85V Li-Polymer Replacement Battery

This is a 3.85V, 2850mAh Li-Polymer cell built to replace the original JG40 battery in the Motorola Moto G7 Plus. It fits the standard G7 Plus, the Dual SIM variant, the Dual SIM TD-LTE model, and the XT1965-6, among other G7 Plus configurations. When the original cell degrades and can no longer hold a stable charge, this swap restores normal device operation.

• G7 Plus model family fit: All G7 Plus variants — including Dual SIM and TD-LTE builds — share the same JG40 connector pinout, cell dimensions (92.20 × 46.26 × 4.10mm), and 3.85V nominal voltage rail. The BMS handshake requirements across these models are identical, so one cell covers the full lineup.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a G7 Plus unit. The BMS accepted the charge profile without interruption, voltage held steady under display and modem load, and the protection circuit tripped correctly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC recalibrate against the new cell's discharge curve before high-current fast charging pushes current into an uncalibrated cell.

Why the G7 Plus reports wrong battery percentage after a cell swap

The G7 Plus uses a coulomb counter inside the fuel gauge IC that builds its percentage model against the original cell's charge curve over hundreds of cycles. When a new cell goes in, that learned curve no longer matches the fresh cell's actual voltage-to-capacity relationship. The IC keeps referencing the old data, so percentage readings drift — often showing full charge too early or dropping suddenly near 20%. One full discharge down to automatic shutdown, followed by an uninterrupted charge to 100%, forces the coulomb counter to remap against the new cell and corrects the readout.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage cliff issue, not a capacity fault. Under peak load — 5G/LTE modem bursts, screen at full brightness, or GPS active — the cell's internal resistance briefly causes voltage to sag below the BMS cutoff threshold even while the fuel gauge still reads 20–30%. The phone shuts down to protect the cell, not because it's empty. Completing two or three full discharge-charge cycles stabilises the cell's internal resistance and narrows the gap between the fuel gauge reading and actual deliverable voltage. If shutdowns persist past the third cycle, verify the cell resting voltage sits at or above 3.85V with a multimeter before reinstalling.