About this replacement
Socketmobile Sonim XP3-S — 3.7V Li-ion Replacement Battery (XP3-0001100-2)
This is a 3.7V, 1200mAh Li-ion cell replacing OEM part XP3-0001100-2 in the Sonim XP3-S and XP3 Enduro rugged smartphones. Both models share the same battery bay dimensions and connector, so one cell fits the full pair. Capacity is 1200mAh (4.44Wh), matching the original spec.
- XP3-S and XP3 Enduro compatibility: Both devices run the same 3.7V voltage rail, identical physical footprint at 56.02 × 35.56 × 6.08mm, and use the same BMS handshake. The connector seats and locks the same way on either unit — no adapter needed.
- Bench tested on actual hardware: We cycled this cell through full charge and discharge on the XP3-S. The BMS accepted the cell without fault codes, protection circuits tripped correctly at low-voltage threshold, and charge current tapered as expected in the CV phase.
- Fuel gauge recalibration on first install: After fitting a new cell, disable fast charging and run one complete discharge-to-charge cycle. The XP3-S fuel gauge IC is calibrated to the old cell's discharge curve. One full cycle lets it recalibrate against the new cell before high-current charging begins.
Sudden shutdown at 20–30% on the Sonim XP3-S after a cell swap
The XP3-S uses a coulomb counter that was mapped to the original cell's internal resistance and voltage-discharge curve. A new cell has different impedance characteristics, so the fuel gauge misjudges the remaining capacity. Under modem transmit or screen load, voltage sags below the shutdown threshold before the gauge reaches 0%. One full discharge-charge cycle corrects the mapping and stops premature shutdowns.
XP3-S reads wrong battery percentage after replacement
The fuel gauge IC stores charge-state data tied to the previous cell's behaviour — after a swap, that stored data is stale. The phone may show 80% on a nearly empty cell or drop from 50% to 10% without warning. Power the device fully off, charge uninterrupted to 100%, then drain it completely to near shutdown. After one full cycle the gauge recalibrates and percentage readings stabilise.