CAT B35 Compatible Battery TYS13G02Q 3.8V 2300mAh

CAT B35 — 3.8V Li-Polymer Replacement Battery (TYS13G02Q)

This 3.8V, 2300mAh Li-Polymer cell is a direct swap for the original TYS13G02Q battery in the CAT B35 rugged smartphone. The B35 is a compact, hardened handset built for field use — calls, messaging, and lightweight apps in tough conditions. Install this cell when the original no longer powers the phone through a working day or fails to charge past a low threshold.

• CAT B35 fit: The B35 uses a single-cell Li-Polymer pack at 3.8V nominal with a three-contact connector carrying charge, ground, and a data line to the fuel gauge IC. This replacement matches that connector pinout and communicates correctly with the phone's onboard battery management system.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on B35 hardware. The BMS accepted the cell without error flags, charge termination triggered correctly at 4.2V, and the protection circuit tripped as expected at the undervoltage threshold.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging and run one complete discharge-to-charge cycle at standard rate. This lets the fuel gauge IC map the new cell's discharge curve before committing learned capacity data — skipping this step causes erratic percentage readings in the first few days.

Sudden shutdown at 20–30% on the CAT B35 after a cell swap

The CAT B35 fuel gauge IC stores a discharge curve learned from the original cell. When a new cell goes in, the old curve stays in memory. The new cell's actual voltage under modem or screen load drops faster than the IC predicts — so the phone cuts power before the percentage reaches zero. This is a calibration mismatch, not a fault with the replacement cell. Run two full discharge-charge cycles at standard rate and the IC will relearn the curve against the new cell's actual voltage behaviour.

CAT B35 not powering on after storage with a flat battery

Li-Polymer cells discharged below approximately 2.5V trigger a BMS lockout — the protection circuit opens and the phone will not respond to the power button or a charger. The B35 shows no screen, no vibration, nothing. Connect the phone to a wall charger using the original cable and leave it for 20–30 minutes without pressing anything. Most BMS circuits on these cells include a trickle-recovery path that slowly raises cell voltage back above the lockout threshold — once the cell reaches around 3.0V, the phone will begin a normal charge sequence and the screen will respond.