Samsung SGH-S200 Replacement Battery 3.7V 750mAh Li-ion

Samsung SGH-S200 Series — 3.7V Li-ion Replacement Battery

This is a 3.7V Li-ion cell rated at 750mAh (2.78Wh), built to fit the Samsung SGH-S200, SGH-S208, SGH-Q200, and SGH-Q208 flip phones. These are early-2000s compact handsets that use a slim Li-ion pack with a low-current charge profile. If the original cell no longer holds voltage under call load, this is the direct swap.

• SGH-S200, S208, Q200, Q208 compatibility: All four models share the same battery bay geometry, connector pinout, and 3.7V nominal charge rail. The BMS on each handset communicates the same cutoff thresholds, so one cell fits all four without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the SGH-S200 platform. The BMS accepted the cell without fault codes, charge termination triggered correctly at 4.2V, and low-voltage cutoff engaged cleanly near 3.0V per cell.
• Fuel gauge recalibration on first use: After installing this cell, run one complete discharge down to automatic shutoff before recharging. The SGH-S200 fuel gauge IC was calibrated to the original cell's discharge curve — a full cycle lets it remap against the new cell and report accurate percentages from cycle two onward.

Sudden shutdown at 20–30% on the SGH-S200 after a cell swap

The SGH-S200 fuel gauge IC stores a discharge curve from the previous cell in non-volatile memory. When a new cell is installed, the IC applies the old curve to the new cell's actual voltage output. At around 20–30% reported charge, the new cell's real voltage drops below what the old curve predicts, and the handset triggers a low-voltage shutdown even though capacity remains. One full discharge-to-cutoff cycle forces the IC to relearn the new curve. After that cycle, shutdowns at falsely reported percentages stop.

Phone not powering on after the replacement cell sat in storage

Li-ion cells self-discharge during storage. If this battery sat below 2.5V before installation, the BMS may have entered lockout mode to prevent cell damage — the handset will show no response when the power button is pressed. Connect the phone to a charger and leave it for 15–20 minutes without attempting to power on. The charge IC trickle-charges the cell back above the BMS recovery threshold, typically around 2.9V, at which point the BMS releases lockout and the phone will power on normally.