T-Mobile MDA Vario Replacement Battery WIZA16 3.7V 2350mAh

T-Mobile MDA Vario — 3.7V Li-ion Replacement Battery (WIZA16)

This is a 3.7V, 2350mAh Li-ion cell built to fit the T-Mobile MDA Vario, MDA Usm, and MDA IV 4. These Windows Mobile devices use the WIZA16 battery format — the same connector, footprint, and voltage rail across the three models. If your MDA Vario no longer holds a charge or dies unexpectedly, this cell is the direct swap.

• MDA Vario / MDA Usm / MDA IV 4 fitment: All three models share the WIZA16 footprint and 3.7V nominal rail. The BMS handshake and connector orientation are identical across the lineup, so one cell covers all three without modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the MDA platform. The BMS accepted charging at standard rates and hit the expected 4.2V cutoff without tripping protection. Capacity delivery matched the 2350mAh rating at room temperature.
• Fuel gauge recalibration on first use: After installing a new cell, run one complete discharge to auto-shutoff before recharging fully. The MDA's fuel gauge IC carries the old cell's discharge curve in memory — skipping this step causes the percentage counter to read inaccurately from the first hour of use.

Why the MDA Vario reports wrong battery percentage after a cell swap

The MDA Vario uses a coulomb-counting fuel gauge IC that maps percentage against a learned discharge curve from the previous cell. Drop in a fresh 2350mAh cell and that stored curve no longer matches the new cell's voltage-versus-charge profile. The gauge will show full charge sooner than the cell actually reaches 4.2V, or it will read 50% while the cell is nearly depleted. One full discharge-to-shutoff followed by an uninterrupted charge to 4.2V lets the IC rebuild its internal model against the new cell. After that single cycle, percentage readings stabilise.

Sudden shutdown at 20–30% on the MDA Vario

This happens when the cell voltage drops below the BMS protection threshold under load — typically when the radio stack or backlight draws peak current. An aged cell loses its ability to sustain voltage under that draw, so the BMS cuts output even though the fuel gauge still shows charge remaining. On a fresh replacement cell, this symptom disappears because the new cell holds voltage above the 3.0V cutoff through high-draw events. If it persists on a new cell, check that the battery contacts are clean and fully seated — poor contact adds resistance that amplifies voltage sag under load.