Caterpillar S50 Replacement Battery 3.8V 2600mAh

CATERPILLAR S50 — 3.8V Li-Polymer Replacement Battery (CUBA-BL-00-S50-000)

This is a 3.8V, 2600mAh Li-Polymer cell for the CATERPILLAR S50 smartphone. It replaces the original battery when charge no longer holds or the phone shuts down unexpectedly under load. Dimensions are 57.70 × 56.00 × 6.30mm — confirm these against your existing cell before ordering.

• S50 platform fit: The S50 uses a single-cell Li-Polymer pack with a dedicated fuel gauge IC that tracks cell state via coulomb counting. Any replacement cell must match the original voltage curve closely — mismatched cells cause the fuel gauge to report inaccurate percentages until a full recalibration cycle is complete.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the S50 platform. The BMS accepted the cell without flagging an unrecognised pack, and charge termination triggered cleanly at full capacity with no erratic current behaviour from the charge IC.
• First cycle after installation: On first use, disable fast charging and complete one full discharge-to-charge cycle at standard rate. This gives the fuel gauge IC one clean pass to map the new cell's discharge curve before high-current charging pushes current into an uncalibrated state.

Why the S50 reports wrong battery percentage after a cell swap

The S50 uses a coulomb counter to track charge state, and that counter is calibrated against the original cell's specific discharge curve. When a new cell goes in, the stored calibration data no longer matches the actual cell behaviour. The phone may show 30% and still keep running, or jump from 50% to 10% without warning. One complete discharge cycle — from 100% down to automatic shutdown, then a full charge — forces the fuel gauge IC to rebuild its calibration table against the new cell.

Sudden shutdown at 15–25% on the replacement cell

This happens when the cell voltage drops sharply under a high-current load — typically the modem during a call or the screen at full brightness — before the displayed percentage suggests it should. A new Li-Polymer cell with a slightly different internal resistance curve can hit the BMS undervoltage cutoff at 3.0V per cell while the fuel gauge still reads well above zero. The fix is the same recalibration cycle: run the phone to automatic shutdown, charge fully to 100%, and repeat once more. After two full cycles the fuel gauge IC aligns its cutoff prediction to the actual voltage behaviour of the new cell.