Doro Liberto 650 Replacement Battery DBI-800B 3.7V 700mAh

Doro Liberto 650 / Secure 580 — 3.7V Li-ion Replacement Battery (DBI-800B)

This is a 3.7V, 700mAh Li-ion cell for the Doro Liberto 650, Secure 580, and Secure 580IUP — three senior-focused phones that share the same battery bay and connector. It replaces OEM part numbers DBI-800B, DBI-800C, and DBI-800D. Capacity is 700mAh (2.59Wh), matching the original specification.

• Liberto 650, Secure 580, and Secure 580IUP compatibility: All three models use the same 3.7V cell footprint, connector pinout, and BMS handshake protocol. One replacement part covers the full range — no hardware differences between variants affect fitment.
• Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on the Liberto 650 platform. The BMS accepted the cell without fault flags, charge termination triggered correctly at 4.2V, and the fuel gauge IC tracked capacity without erratic jumps after the first full cycle.
• First-cycle fuel gauge reset: After fitting this battery, run one full discharge down to the auto-shutdown point, then charge uninterrupted to 100%. The phone's fuel gauge IC is still calibrated to the old cell's discharge curve — skipping this step causes the percentage readout to drift or shut down early at 20–30% remaining.

Why the Liberto 650 reports wrong battery percentage after a cell swap

The Liberto 650 uses a coulomb counter in the fuel gauge IC to track state of charge. That counter builds its model against the discharge curve of the original cell. When a new cell goes in, the stored curve no longer matches the actual voltage-to-capacity relationship of the replacement. The result is a percentage display that reads higher or lower than reality — sometimes by 15–20%. One complete discharge-charge cycle lets the IC relearn the new cell's curve and corrects the readout.

Sudden shutdown at 20–30% on the replacement cell

This is a voltage sag issue, not a capacity fault. At 20–30% state of charge, the cell's internal voltage drops sharply under the load of the modem or display backlight — a behaviour called a voltage cliff. If the fuel gauge IC hasn't recalibrated yet, it doesn't anticipate this cliff and doesn't warn the OS in time. The phone cuts power to protect the cell before the OS can trigger a graceful shutdown. Run one full discharge cycle to the auto-off point, then recharge fully to 4.2V — this recalibrates the gauge and eliminates premature shutdowns.