About this replacement
Motorola E1000 / Ming / A1200 Series — 3.7V Li-ion Replacement Battery (BQ50 / SNN5766A)
This 3.7V 800mAh Li-ion cell replaces the original BQ50, BT50, SNN5766A, SNN5771A, SNN5804A, and related OEM part numbers. It fits the Motorola E1000, Ming, A1200, V361, and over 100 compatible models in the same battery family. Voltage and connector geometry match OEM spec — the fuel gauge IC can read this cell without modification.
- E1000 / Ming / A1200 platform fit: These models share a common 3.7V single-cell architecture, the same contact pin layout, and the same BMS handshake protocol — which is why one cell part number covers all of them. The BQ50 family was Motorola's standardised mid-2000s battery platform across multiple GSM handsets.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on a Motorola E1000 unit. The BMS accepted the cell without fault flags, charge current tapered correctly at full capacity, and the protection circuit tripped as expected on a hard short test.
- Fuel gauge recalibration on first use: Disable fast charging for the first complete discharge-charge cycle after fitting this cell. The fuel gauge IC was calibrated to your old cell's discharge curve — one full cycle at standard charge current lets it remap against the new cell before higher charge rates are applied.
Sudden shutdown at 20–30% on the Motorola E1000 after a cell replacement
This happens because the fuel gauge IC still holds the discharge curve of the old, degraded cell. When the new cell hits a load spike — GSM radio transmission or backlight at full brightness — voltage drops briefly below the threshold the IC mapped to 20–30%, triggering an emergency shutdown. The phone interprets the voltage sag as a near-empty cell even though capacity remains. One full discharge to 3.4V followed by a complete standard-rate charge resets the coulomb counter and resolves the false cutoff.
Phone not powering on after the replacement cell sat in storage
Li-ion cells self-discharge in storage, and if this cell dropped below approximately 2.5V per cell before installation, the BMS will have entered lockout mode to prevent damage. The phone will show nothing — no charge indicator, no boot screen. Connect the phone to a wall adapter rated at 5V and leave it for 15–20 minutes without pressing anything; the charge IC needs sustained input voltage to trickle-charge the cell back above the BMS re-enable threshold of around 2.7V before normal charging resumes.