Sanyo SCP-35LBPS Replacement Battery 3.7V 1100mAh Li-ion

Sanyo SCP-3810 — 3.7V Li-ion Replacement Battery (SCP-35LBPS)

This is a 3.7V, 1100mAh Li-ion replacement cell for the Sanyo SCP-3810 and Mirro SCP-3810 candybar-style mobile phones. It matches the OEM part number SCP-35LBPS and fits the original battery compartment at 54.20 × 33.10 × 5.20mm. Swap it when the original cell no longer holds enough charge to get through a day of calls.

• SCP-3810 and Mirro SCP-3810 fit: Both models share the same battery bay dimensions, connector pinout, and 3.7V nominal voltage rail — one cell covers both. The BMS communicates over the same two-pin thermistor line used across this Sanyo handset family.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the SCP-3810 platform. The BMS held charge termination at 4.2V and engaged undervoltage lockout cleanly at 3.0V with no false cutoffs mid-cycle.
• Fuel gauge recalibration on first cycle: After fitting this cell, run one complete discharge to auto-off before recharging. The SCP-3810's fuel gauge IC carries the old cell's discharge curve in memory — one full cycle overwrites it against the new cell's actual characteristics and stops erratic percentage readings.

Sudden shutdown at 20–30% on the SCP-3810 after a cell swap

Aged Li-ion cells develop a steep voltage cliff — voltage drops sharply under modem transmit or backlight load before the fuel gauge registers low. The phone's protection circuit reads that voltage drop as a hard undervoltage event and cuts power instantly, even though the displayed percentage still shows charge remaining. A new cell has a flatter discharge curve, but the fuel gauge IC is still calibrated to the old cell's steep cliff. Run one full discharge-to-shutdown cycle and then a full charge — the coulomb counter resets its endpoint map and the shutdowns stop.

SCP-3810 not powering on after sitting in storage

Li-ion cells in storage self-discharge over months. If the cell drops below 2.5V per cell, the BMS enters deep-discharge lockout and blocks all charge current to prevent cell damage. Plugging into a standard charger does nothing — the phone shows no charge indicator and will not boot. Connect the phone to a USB charger and leave it completely undisturbed for 20–30 minutes; the charge IC on some Sanyo handsets trickle-charges at a low pre-qualification current to bring the cell back above the 2.7V recovery threshold before resuming normal CC/CV charging.