About this replacement
Samsung SGH-D830 / SGH-D838 — 3.7V Li-ion Replacement Battery (BST4048BE)
This is a 3.7V, 1500mAh Li-ion replacement battery for the Samsung SGH-D830 and SGH-D838 slider phones. Part number BST4048BE (also cross-referenced as AB423643CE) matches the original cell specification. Voltage and capacity are drawn from the product data — 5.55Wh total energy.
- SGH-D830 and SGH-D838 compatibility: Both models share the same battery bay dimensions, connector pinout, and 3.7V charging rail. The BMS handshake on each uses the same NTC thermistor line, so one cell covers both variants without any modification.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on the SGH-D830 platform. The BMS handled charge termination cleanly at 4.2V and held cutoff above 3.0V under load without tripping a false protection event.
- Fuel gauge recalibration on first use: On the first full cycle after installing this battery, let the phone discharge completely until it shuts itself off, then charge uninterrupted to 100%. This gives the fuel gauge IC one clean reference curve against the new cell before normal use resumes.
Sudden shutdown at 20–30% on the SGH-D830 after a cell swap
The SGH-D830's fuel gauge IC was calibrated to the discharge curve of the original aged cell. A new cell with a steeper voltage cliff at low state-of-charge can drop below the modem's minimum supply voltage before the gauge reads zero. The phone reads 25% but the cell voltage is already collapsing under the RF transmit load. One full discharge-to-shutdown followed by an uninterrupted charge to 100% resets the coulomb counter and aligns the gauge to the new cell's actual curve.
Phone reporting wrong battery percentage after replacement
The percentage displayed is calculated by the fuel gauge IC using a stored discharge model built from cycles on the previous cell. When you fit a new 1500mAh cell, the IC applies the old model and the reading drifts — often showing 80% when the cell is near full, or dropping suddenly at low charge. This is not a fault with the replacement cell. Force a full recalibration cycle: run the phone down to automatic shutdown, then charge continuously to 100% without interruption. After one complete cycle the gauge tracks the new cell accurately.