Bea-fon SL880 Touch Replacement Battery 3.7V 1450mAh

Bea-fon SL880 Touch / SL800 4G — 3.7V Li-Polymer Replacement Battery (SL880)

This 3.7V, 1450mAh lithium-polymer cell replaces the original battery in the Bea-fon SL880 Touch and SL800 4G candybar feature phones. It matches the OEM dimensions at 58.90 × 44.00 × 5.20mm, so it seats correctly in the battery bay without modification. Capacity figure is taken directly from product data at 5.37Wh.

• SL880 Touch and SL800 4G compatibility: Both models share the same battery bay dimensions, connector pinout, and 3.7V nominal voltage rail, so a single cell covers either device without any wiring changes.
• Bench tested on actual hardware: We cycled this cell through full charge and load discharge on the bench. The BMS held the charge cutoff at 4.2V and triggered low-voltage protection cleanly at the bottom of the discharge curve without false tripping under simulated call-load current draw.
• Fuel gauge recalibration on first cycle: After fitting this cell, run one complete discharge down to automatic shutdown, then charge uninterrupted to 100% before normal use. The SL880's fuel gauge IC was calibrated against the old cell's discharge curve — skipping this step causes the percentage counter to read incorrectly for the first several days of use.

Sudden shutdown at 20–30% on the SL880 Touch after a cell swap

The SL880 Touch uses a fuel gauge IC that tracks charge state against a stored discharge curve from the original cell. A new cell has a slightly different internal resistance profile, so the IC underestimates how close the voltage is to the cutoff threshold. Under modem load — an active call or a 4G data burst — the cell voltage sags sharply below what the gauge expects, and the phone shuts off even though the display shows 20–30% remaining. One full discharge-charge cycle lets the IC re-map the curve against the new cell. After that cycle, the reported percentage and the actual cutoff point realign.

Phone won't power on after the replacement cell sat in storage

Lithium-polymer cells self-discharge during storage. If this battery sat long enough to drop below approximately 2.5V per cell, the BMS enters lockout mode to prevent damage and the phone shows no response on the power button. Connect the phone to a charger and leave it for 15–20 minutes without pressing anything — the charge IC trickle-charges the cell back above the BMS recovery threshold. Once voltage recovers past that point, the BMS re-initialises and the phone boots normally. If the screen shows no charging indicator after 30 minutes on the charger, try a different USB cable before assuming the cell is faulty.