About this replacement
Sagem MC932 / MC928 Series — 3.7V Li-ion Replacement Battery (238127153)
This is a 3.7V 1000mAh Li-ion cell for the Sagem MC932, MC928, MC959, MC918, and over 20 additional Sagem handsets. It replaces OEM part numbers 238127153, 238191851, 238191851 N4, and 238191851 N5. Capacity figures come from the product data — 1000mAh / 3.7Wh.
- MC900 series compatibility: The MC918, MC928, MC932, and MC959 share the same battery bay dimensions (81.40 × 48.30 × 9.70mm), connector pinout, and 3.7V voltage rail — one cell format covers the whole platform.
- Bench tested on actual hardware: We cycled this cell through full charge and load discharge on compatible hardware. The BMS held charge termination correctly and showed no false-positive cutoff during moderate screen-and-call load.
- Fuel gauge recalibration on first use: After fitting, disable any fast-charge mode and run one complete discharge-to-charge cycle. This lets the fuel gauge IC map the new cell's actual discharge curve before high-current charging is applied to an uncalibrated cell.
Sudden shutdown at 20–30% on the MC932 after a cell swap
The MC932's fuel gauge IC retains the discharge curve from the old, degraded cell. When the new cell hits its voltage cliff — typically around 3.5V under modem or display load — the gauge still thinks reserve capacity remains. The phone cuts out because the cell voltage drops below the BMS floor, not because the gauge says zero. One full discharge to automatic shutdown followed by a complete charge resets the coulomb counter and realigns the curve. After that cycle, shutdowns at 20–30% stop.
Phone won't power on after the replacement battery sat in storage
Li-ion cells stored uncharged self-discharge over time. If the cell drops below approximately 2.5V, the BMS locks out to prevent damage — the phone shows nothing when you press power. Connect the handset to a low-current charger (a standard 5V USB wall adapter, not a fast charger) and leave it for 20–30 minutes without pressing anything. The BMS requires a trickle input to exit lockout before normal charging resumes. Once the screen shows a charge indicator, the cell has recovered above the BMS floor.