Mobistel Cynus E1 BTY26185 Compatible Battery 3.7V 1000mAh

Mobistel Cynus E1 — 3.7V Li-ion Replacement Battery (BTY26185)

This is a 3.7V, 1000mAh Li-ion cell built to replace the original battery in the Mobistel Cynus E1 and MT-350b smartphones. It matches the OEM voltage, capacity, and physical dimensions (48.23 × 49.06 × 5.30mm) of the factory-installed unit. Swap it in when the original cell can no longer hold a charge or shuts the phone down unexpectedly.

• Cynus E1 and MT-350b compatibility: Both models share the same battery bay dimensions, connector pinout, and 3.7V nominal voltage rail. The BTY26185 fits both without modification to the housing or flex cable routing.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the Cynus E1 platform. The BMS accepted charge current correctly, balanced cell voltage at 4.2V, and triggered low-voltage cutoff at the expected threshold without false trips.
• Fuel gauge recalibration after installation: After fitting this cell, run one complete discharge down to automatic shutdown, then charge uninterrupted to 100% before normal use. This lets the phone's fuel gauge IC map the new cell's actual discharge curve and prevents erratic percentage readings from the first session onward.

Sudden shutdown at 20–30% on the Cynus E1 after a cell swap

The Cynus E1's fuel gauge IC retains the discharge curve of the old, degraded cell in its coulomb counter registers. When the modem transmits or the screen brightness spikes, current draw briefly exceeds what the IC expects at that state of charge. The phone reads the resulting voltage dip as critically low and cuts power — even though the replacement cell has capacity remaining. One full discharge-to-shutdown and uninterrupted recharge cycle forces the IC to relearn the new cell's curve and eliminates most of these mid-use cutoffs.

Phone shows 100% immediately after charging starts on new cell

A freshly installed cell with no charge history confuses the fuel gauge IC — it has no reference point for the cell's actual open-circuit voltage curve, so it can report a full charge within minutes of plugging in. This is a calibration artefact, not a fault with the cell itself. Let the phone charge uninterrupted until the charging indicator clears naturally, then discharge it fully in one session. After that single cycle, the IC anchors its readings to the actual 3.7V nominal and 4.2V full-charge endpoints of this cell.