BTY26182 Mobistel Cynus T5 Replacement Battery 3.7V 2000mAh

Mobistel Cynus T5 — 3.7V Li-ion Replacement Battery (BTY26182)

This is a 3.7V, 2000mAh Li-ion replacement battery for the Mobistel Cynus T5 smartphone. It fits the MT-9201w, MT-9201b, and MT-9201S variants — all share the same battery bay and connector. Swap this in when the original cell can no longer hold a working charge through a full day.

• Cynus T5 and MT-9201 variants: The MT-9201w, MT-9201b, and MT-9201S use the same PCB layout, connector pitch, and BMS handshake protocol as the standard Cynus T5. One cell covers all four model codes.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the Cynus T5 platform. The BMS accepted the cell without triggering overcurrent or thermal cutoff flags on the first cycle.
• First-cycle fuel gauge reset: After installation, disable fast charging and run one complete discharge-charge cycle from 100% down to automatic shutdown and back to full. This lets the fuel gauge IC map the new cell's discharge curve before the OS begins drawing on its percentage estimates.

Why the Cynus T5 reports wrong battery percentage after a cell swap

The Cynus T5 uses a fuel gauge IC that builds its percentage model from the coulomb counter data of the original cell. When you fit a new cell, that calibration is stale — the IC is still reading against the old discharge curve. The phone may show 40% and shut down moments later, or sit at 1% for an extended period. One full uninterrupted discharge-charge cycle resets the coulomb counter and lets the IC relearn the new cell's actual capacity. After that cycle, percentage reporting stabilises.

Sudden shutdown at 20–30% on the new cell

This happens when the modem radio or display backlight draws a current spike the cell cannot sustain at that state of charge. Voltage drops below the BMS cutoff threshold — around 3.0V — and the phone cuts power before the percentage reaches zero. It is not a faulty cell; it is the fuel gauge reporting a percentage that does not match actual usable voltage under load. Run two full discharge-charge cycles so the IC recalibrates, then recheck. If shutdowns persist below 3.2V under load, check that the battery connector is fully seated and making clean contact.