About this replacement
Samsung SGH-F400 / GT-M7500 Series — 3.7V Li-ion Replacement Battery (AB463651BE)
This is a 3.7V, 650mAh Li-ion cell built to the AB463651BE specification. It fits the Samsung SGH-F400, SGH-F408, GT-M7500, GT-M7500 Emporio Armani, and over 80 additional Samsung handsets sharing the same battery bay and connector pinout. Dimensions are 54.34 × 35.49 × 4.35mm — verify your original cell before installing.
- SGH-F400 and GT-M7500 platform fitment: Both model lines share the same physical battery cavity, three-pin connector, and BMS handshake protocol, which is why a single OEM part number — AB463651BE — covers the full range. The charge IC on the mainboard reads the thermistor pin on the cell; a mismatched cell without that pin will refuse to charge.
- Bench tested on actual hardware: We cycled this cell in an SGH-F400 and monitored BMS cutoff at both ends. The protection circuit tripped at 4.2V on the charge side and held the low-voltage cutoff at 3.0V — both within Samsung's original specification for this handset.
- Fuel gauge recalibration on first use: After installing this cell, run one full discharge to near-empty before recharging to 100%. The SGH-F400's fuel gauge IC was calibrated against your original cell's discharge curve. Skipping this step causes the phone to report inaccurate percentages for the first several cycles.
Why the SGH-F400 reports wrong battery percentage after a cell swap
The fuel gauge IC in the SGH-F400 tracks charge state using a coulomb counter that was trained on the original cell's internal resistance and discharge curve. A new cell has different impedance characteristics, so the counter's reference points are immediately out of sync. The phone will often report 100% for longer than expected, then drop suddenly — not because the cell is failing, but because the IC hasn't mapped the new curve yet. One full discharge-charge cycle gives the IC enough data to recalibrate. After that cycle, percentage readings stabilise.
Sudden shutdown at 20–30% on a replacement cell
This is a voltage cliff failure, not a capacity problem. At around 20–30% state of charge, the cell voltage drops into a range where it cannot sustain the current draw from the RF modem firing during a call or data burst. The phone's protection circuit sees the instantaneous voltage sag fall below 3.0V and shuts the device down even though the fuel gauge still shows charge remaining. Confirm the cell is genuine by checking the resting voltage after shutdown — it should recover to at least 3.5V within a few minutes. If it does not recover above 3.4V, the cell has a high internal resistance fault and should be replaced.