Motorola Droid Turbo EQ40 Replacement Battery 3.8V 3900mAh

Motorola Droid Turbo XT1254 — 3.8V Li-Polymer Replacement Battery (EQ40 / SNN5949A)

This is a 3.8V, 3900mAh lithium-polymer cell built to replace the original EQ40 battery in the Motorola Droid Turbo, Droid Turbo LTE, and XT1254. It fits the same physical pocket and uses the same connector as the factory cell. Capacity matches the OEM specification at 14.82Wh.

• Droid Turbo / XT1254 platform fit: The Droid Turbo, Droid Turbo LTE, and Quark variants all share the same battery bay geometry, flex connector, and BMS handshake. One cell covers the full XT1254 hardware range without modification.
• Bench tested on actual hardware: We ran this cell through a full charge cycle on an XT1254 unit. The BMS accepted the charge handshake without fault codes, and cell voltage held flat across the mid-range discharge curve at load.
• Fuel gauge recalibration on first use: After installation, disable Motorola Turbo Charging for the first complete discharge-to-charge cycle. This gives the fuel gauge IC time to map the new cell's discharge curve before high-current charging pushes current into an uncalibrated coulomb counter.

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

The Droid Turbo's modem and display draw sharp current spikes that expose a voltage cliff in aged or freshly installed cells. When the cell voltage drops below roughly 3.5V under that spike load, the BMS trips the cutoff before the OS registers low battery. The phone reads 25% and shuts off because the fuel gauge IC is still calibrated to the old cell's discharge curve. One full uninterrupted discharge cycle — letting the phone run to automatic shutdown, then charging to 100% without interruption — resets the coulomb counter against the new cell and eliminates the false cliff.

USB-PD or Turbo Charge not activating on first cycle after replacement

On the first charge cycle after installation, the Droid Turbo's charge IC may default to standard 5V/1A input and refuse to negotiate the Turbo Charging protocol. This happens because the charge controller treats a new BMS as unverified and applies a conservative handshake until it completes one full cycle. Plug into the original Motorola Turbo Charger, complete one full 0–100% charge without unplugging, and the charge IC will negotiate the higher current rate normally from the second cycle onward.