Medion MD41900 Compatible Battery 3.7V 750mAh Li-ion

Medion MD41900 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 750mAh Li-ion cell for the Medion MD41900 smartphone. It replaces the original battery when the phone can no longer hold charge, shuts down unexpectedly, or will not power on. Dimensions are 54.67 × 42.00 × 7.00mm — confirm these against the original cell before fitting.

• MD41900 fit: The MD41900 runs a single-cell 3.7V Li-ion architecture with a direct PCM connection to the phone's charge IC. This cell matches the voltage rail, physical footprint, and connector orientation that the board expects.
• Bench tested on actual hardware: We ran charge and discharge cycles through the BMS on this cell class. The protection circuit responded correctly to cutoff at low voltage and did not trip on normal charge current from the stock charge IC.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging if available and run one full discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before it starts reporting accurate percentages.

Sudden shutdown at 20–30% on the MD41900 after a cell swap

This happens because the fuel gauge IC is still using the discharge curve from the old, degraded cell. The new cell has a steeper voltage drop under modem and screen load than the IC expects, so it reads 25% right up until the voltage collapses below the cutoff threshold. The phone interprets that collapse as a dead battery and shuts down immediately. One full discharge-to-shutdown followed by a full charge resets the coulomb counter and corrects the reporting. After that cycle, percentage readings track the actual cell state within a few percent.

MD41900 not powering on after the replacement cell sat in storage

Li-ion cells self-discharge during storage. If the cell voltage drops below approximately 2.5V, the BMS enters lockout mode and blocks current flow to protect the cell from damage. The phone will show nothing — no charging animation, no response — when you plug in the cable. To recover, connect the original charger and leave it for 15–30 minutes without pressing the power button. The charge IC trickle-charges the cell back above the BMS re-enable threshold, typically around 2.9V, at which point normal charging resumes.