About this replacement
Motorola Moto G Stylus 5G 2021 — 3.85V Li-Polymer Replacement Battery (MD50)
This 3.85V, 4700mAh lithium-polymer cell replaces the original MD50 battery in the Motorola Moto G Stylus 5G 2021. It fits the XT2131, XT2131-1, and XT2131-3 variants. Capacity figure is taken directly from the product data — 18.1Wh total energy.
- XT2131 variant compatibility: The XT2131, XT2131-1, and XT2131-3 all share the same battery bay dimensions, connector pinout, and BMS handshake protocol — that is why one cell covers the full production run of this model.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on an XT2131 unit. The BMS accepted charge current without tripping, and the fuel gauge IC tracked state-of-charge correctly by the second full cycle.
- First-cycle fast-charge tip: On first use after installation, disable fast charging for one complete discharge-charge cycle. This gives the fuel gauge IC time to recalibrate against the new cell's discharge curve before high-current charging pushes energy into an uncalibrated cell.
Why the Moto G Stylus 5G 2021 reports wrong battery percentage after a cell swap
The phone's fuel gauge IC stores a learned discharge curve from the original cell. After you swap in a new cell, that stored curve no longer matches the new cell's actual voltage-to-capacity relationship. The result is percentage readings that jump, stick, or don't match real remaining capacity. One full slow discharge down to automatic shutdown, followed by a full charge to 100%, forces the coulomb counter to relearn the curve against the new cell.
Sudden shutdown at 20–30% on the replacement cell
This happens when the 5G modem or the display draws a current spike the cell cannot sustain at low state-of-charge. Voltage drops sharply below the BMS cutoff threshold — typically around 3.2V under load — and the phone shuts off even though the gauge still shows charge remaining. It is most common before the fuel gauge IC has completed its first recalibration cycle. Run one full slow discharge-to-shutdown cycle, then charge fully to 100%, and the gauge will better predict the voltage cliff before the BMS trips.