About this replacement
Motorola Moto Z Play / XT1635 — 3.8V Li-Polymer Replacement Battery (GL40 / SNN5974A)
This is a 3.8V, 3300mAh Li-Polymer cell replacing the original GL40 / SNN5974A battery in the Moto Z Play, Moto Z Play Droid, and XT1635 variants. It fits the same footprint — 100.60 x 50.50 x 4.20 mm — and connects to the same charge IC and fuel gauge on the board. Capacity matches the OEM spec at 12.54Wh.
- XT1635 series compatibility: The XT1635, XT1635-03, Moto Z Play, and Moto Z Play Droid all run the same battery connector, same BMS handshake, and the same 3.8V nominal rail — one cell covers the entire platform without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on XT1635 hardware and confirmed the BMS accepted the cell on first connection, charge termination triggered correctly at 4.35V, and no overcurrent fault codes were logged during a full cycle.
- 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 map the new cell's discharge curve before high-current charging pushes current into an uncalibrated cell — it prevents erratic percentage readings in the first few days.
Sudden shutdown at 20–30% on the Moto Z Play after a cell swap
The XT1635 uses a coulomb counter combined with a voltage-based fuel gauge. When the modem transmits or the screen brightness spikes, current draw briefly jumps and the cell voltage dips sharply. If the fuel gauge IC is still calibrated to the old degraded cell's curve, it reads 25% as safe — but the new cell's actual knee voltage under load triggers a low-voltage protection cutoff before the gauge catches up. One full discharge-charge cycle without fast charging resets the calibration. After that cycle, the gauge tracks the new cell's curve accurately and shutdowns at mid-percentage stop.
Phone not powering on after the GL40 sat in storage for months
Li-Polymer cells self-discharge in storage, and if the GL40 dropped below 2.5V per cell, the BMS enters lockout mode to prevent damage — the phone will show nothing when you press the power button, not even a low-battery screen. Connect the phone to a 5V charger and leave it for 15–20 minutes without pressing anything. The charge IC trickle-charges the cell from below 2.5V up to the threshold where the BMS releases lockout, typically around 3.0V, and the phone will then boot or show a charging indicator normally.