About this replacement
Samsung SGH-W999 / GT-S7530 — 3.7V Li-ion Replacement Battery (EB445163VU)
This is a 3.7V, 1500mAh Li-ion replacement cell for the Samsung SGH-W999, SCH-W999, GT-S7530, and GT-S7530L flip phones. It uses OEM part number EB445163VU and matches the original cell's physical footprint at 62.50 × 50.50 × 4.20mm. Fit the battery and the phone slots back together without modification.
- SGH-W999 and GT-S7530 platform compatibility: Both the SGH-W999 and GT-S7530 series run the same 3.7V single-cell architecture with identical connector pinouts and BMS handshake requirements. One cell covers the full model range listed above.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the SGH-W999 platform. The BMS accepted the charge IC handshake without fault codes, and cell voltage held steady across screen-on and modem-active load phases.
- Fuel gauge recalibration on first use: On first installation, disable fast charging if your network supports it, then run one complete discharge down to automatic cutoff followed by a full charge. This gives the phone's fuel gauge IC one clean cycle to map the new cell's discharge curve before trusting its percentage readings.
Why the SGH-W999 reports wrong battery percentage after a cell swap
The W999's fuel gauge IC stores a discharge curve learned from the original cell over hundreds of cycles. When a new cell goes in, that stored curve no longer matches the actual cell chemistry, so the percentage display drifts — often reading high then dropping sharply. The fix is one full discharge-to-cutoff and uninterrupted charge cycle with the phone powered on throughout. After that cycle, the coulomb counter resets its baseline and percentage tracking stabilises to within a few percent of actual remaining capacity.
Sudden shutdown at 20–30% on the replacement cell
This is a voltage cliff failure, not a capacity problem. When the modem transmits or the screen backlight peaks, current draw spikes and pulls cell voltage below the BMS cutoff threshold — even though the reported percentage looked safe. On a fresh cell that hasn't been calibrated, the fuel gauge IC underestimates how close the cell is to its floor voltage of 3.0V. Run one full discharge cycle to let the gauge IC learn the new cell's sag curve. After calibration, the phone will call the shutdown earlier and more accurately, and the premature cutoffs will stop.