CAT S48C Replacement Battery 3.8V 3800mAh Li-Polymer

CAT S48C — 3.8V Li-Polymer Replacement Battery (L6880)

This is a 3800mAh, 3.8V Li-Polymer battery that replaces the original L6880 cell in the CAT S48C rugged smartphone. It fits the S48C directly — same connector, same physical footprint at 98.16 × 57.80 × 4.30mm. Capacity is rated at 14.44Wh, matching the original specification.

• CAT S48C platform fit: The S48C uses a fixed voltage rail of 3.8V with a connector and BMS handshake tied specifically to the L6880 cell profile. This replacement matches that voltage and connector configuration so the charge IC accepts the cell without throwing a fault.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the S48C platform and monitored BMS communication throughout. The protection circuit responded correctly to both charge cutoff and low-voltage discharge limits, and the charge IC completed a full cycle without interruption.
• Fuel gauge recalibration after swap: On first use after installing this cell, disable fast charging and run one complete discharge-to-charge cycle at standard current. This lets the fuel gauge IC build an accurate discharge curve against the new cell before the coulomb counter locks in its reference points.

Sudden shutdown at 20–30% on the CAT S48C after a cell swap

The S48C's modem and display together draw sharp current spikes that can drag cell voltage below the BMS cutoff threshold even when the fuel gauge still reads 20–30%. A new Li-Polymer cell has higher internal impedance on its first few cycles, which amplifies that voltage sag under load. The BMS reads the instantaneous voltage drop as a critical low-cell event and cuts power. After two or three full discharge-charge cycles, impedance drops and the shutdowns stop.

USB fast charge not activating on the first cycle after replacement

After a cell swap, the charge IC on the S48C may negotiate a lower charge current on the first cycle while the BMS validates the new cell's parameters. This is not a fault — it is the IC confirming cell impedance and temperature response before stepping up current. Plug in with the original CAT cable, let the first full charge complete at standard current, and fast charging typically re-enables on the next session. If it does not, check that the cable supports the required current rating — the S48C's USB-PD handshake is cable-sensitive.