Caterpillar S60 Replacement Battery 3.85V 3500mAh Li-Polymer

CATERPILLAR S60 — 3.85V Li-Polymer Replacement Battery (APP-12F-F5757I-CGX-111)

This is a 3500mAh Li-Polymer cell at 3.85V, built to fit the CATERPILLAR S60 rugged smartphone. It replaces the original battery directly, restoring power to calls, navigation, and applications. Rated at 13.48Wh, it matches the OEM energy capacity specification for this device.

• S60 platform fit: The S60 uses a fixed connector layout and a BMS that validates cell voltage and impedance at boot. This replacement cell meets that voltage threshold and passes the handshake on power-up without triggering a fault state.
• Bench tested on actual hardware: We cycled this cell under mixed load — screen-on, modem active, GPS running — and monitored BMS behaviour across charge and discharge. The protection circuit held cutoffs at expected thresholds and did not trip under normal S60 draw.
• Fuel gauge recalibration on first cycle: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle. This lets the fuel gauge IC map its coulomb counter against the new cell's actual discharge curve before fast-charge current is applied to an uncalibrated state.

Sudden shutdown at 20–30% on the CATERPILLAR S60 after a cell swap

The S60's fuel gauge IC carries calibration data from the old cell. When a new cell with a different internal resistance goes in, the voltage-to-percentage curve no longer matches. Under modem or screen load, the cell's terminal voltage drops faster than the gauge predicts, so the BMS cuts power before the percentage reaches zero. This is not a fault in the replacement cell — it is a calibration mismatch. Run two full discharge-charge cycles with fast charging off and the gauge will recalibrate against the new cell's actual curve.

USB-PD fast charge not accepted on the first cycle after replacement

The charge IC on the S60 negotiates fast-charge current based on the BMS state reported by the cell. On a fresh cell, the BMS starts in a conservative mode and may reject the higher current envelope until it completes one standard charge cycle. If fast charging is not initiating, plug into a standard 5V charger and complete a full charge first. After that initial cycle, the charge IC will accept the fast-charge handshake and negotiate full current on subsequent charges.