AMOI Momo Design MD2 Compatible Battery 3.7V 900mAh

AMOI Momo Design MD2 — 3.7V Li-ion Replacement Battery (MD-2)

This 3.7V, 900mAh Li-ion cell replaces the original battery in the AMOI Momo Design MD2 and MD02 smartphones. The pack matches the OEM MD-2 part number and the 44.70 × 37.70 × 5.60mm footprint of the original. It restores power to a phone that no longer holds a charge or won't turn on.

• MD2 and MD02 compatibility: Both model designations use the same battery bay dimensions, connector orientation, and charge voltage ceiling. One cell covers both variants — no hardware modification needed.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the MD2 platform. The BMS accepted charge current without fault flags, and the protection circuit tripped correctly at the low-voltage cutoff threshold.
• Fuel gauge recalibration on first use: After fitting this cell, run one full discharge down to automatic shutdown, then charge uninterrupted to 100% before normal use. The MD2's fuel gauge IC reads coulomb data calibrated to the old cell curve — one full cycle resets it against the new cell so percentage readings are accurate.

Sudden shutdown at 20–30% on the Momo Design MD2

This is a voltage-cliff failure, not a capacity problem. When the MD2 fires the modem or lights the display at high brightness, current draw spikes sharply. A degraded or fresh-but-uncalibrated cell can't hold voltage under that load, and the protection circuit cuts output before the reported percentage reaches zero. The phone reads 25% but the cell voltage has already dropped below the BMS floor under load. One complete recalibration cycle — full discharge, full charge — tightens the fuel gauge's voltage-to-percentage mapping and typically eliminates false cutoffs.

MD2 not powering on after the battery sat in storage

Li-ion cells self-discharge in storage. If this battery shipped or sat unused long enough to drop below approximately 2.5V per cell, the BMS enters lockout and blocks charge current as a safety measure. The phone will show nothing — no charging indicator, no boot screen. Connect the phone to a low-current USB charger (500mA wall adapter, not a fast charger) and leave it for 20–30 minutes without pressing the power button. Once the cell climbs back above the BMS recovery threshold, typically around 2.9V, normal charging resumes and the phone will power on.