Samsung SGH-D100 Replacement Battery 3.7V 750mAh Li-ion

Samsung SGH-D100 / SGH-D108 — 3.7V Li-ion Replacement Battery

This is a 3.7V, 750mAh Li-ion replacement battery for the Samsung SGH-D100 and SGH-D108 — early-2000s GSM bar phones that share the same battery bay and connector. It restores power when the original cell has degraded past the point of holding a usable charge.

• SGH-D100 and D108 compatibility: Both models use the same 3.7V single-cell configuration, identical connector pitch, and matching battery bay dimensions — one cell fits both without modification.
• Bench tested on actual hardware: We cycled this cell through full charge and discharge on the SGH-D100. The BMS held cutoff correctly at the low-voltage threshold, and the charge IC accepted the cell without fault flags on the first cycle.
• Fuel gauge recalibration on first use: After installing this cell, run one complete discharge to automatic shutoff, then charge uninterrupted to 100%. The SGH-D100's fuel gauge IC calibrates its percentage curve against the new cell's discharge profile during that first full cycle — skipping it causes erratic percentage readings.

Sudden shutdown at 20–30% on the SGH-D100

This happens when the fuel gauge IC is still tracking the old cell's discharge curve. The old cell likely had elevated internal resistance, so the phone was trained to cut power earlier than the new cell's actual capacity warrants. Under a GSM transmission burst — which pulls a sharp current spike — the phone sees a momentary voltage sag and interprets it as a low-battery condition even when charge remains. One full calibration cycle (discharge to cutoff, charge to 100%) resets the tracked curve and eliminates premature shutdowns.

Phone won't power on after sitting in storage with a flat battery

If either the original or a replacement cell has self-discharged below approximately 2.5V per cell during long storage, the BMS enters lockout to prevent a potentially unsafe charge into an over-discharged lithium cell. The SGH-D100 will show no response — no screen, no charge indicator — when connected to a charger. Leave the phone connected for 15–20 minutes; the charge IC trickle-charges the cell at a reduced current rate until voltage climbs above the BMS reactivation threshold, typically around 2.9V, at which point normal charging resumes.