T-Mobile Catalyst 3622A CPLD-390 Compatible Battery 3.7V 2200mAh

T-Mobile Catalyst 3622A — 3.7V Li-Polymer Replacement Battery (CPLD-390)

This 3.7V 2200mAh Li-Polymer cell replaces the original CPLD-390 battery in the T-Mobile Catalyst 3622A. It fits the candybar-style handset and restores power for calls, messaging, and basic app use. Capacity is rated at 8.14Wh — identical to the factory spec.

• Catalyst 3622A fit: This cell matches the 3622A's connector pinout, physical footprint (71.00 × 52.98 × 5.00mm), and 3.7V nominal rail. The BMS communicates charge state over the same two-wire interface the original uses, so the phone's charge IC accepts it without modification.
• Bench tested on actual hardware: We cycled the cell through charge and discharge on the 3622A platform. The BMS held thermal cutoff within spec and the charge IC completed a full cycle without faulting or dropping into trickle mode early.
• Fuel gauge recalibration on first install: On first use, disable any fast-charge setting and run one full discharge-to-charge cycle before normal operation. This lets the fuel gauge IC build an accurate discharge curve against the new cell — skipping this step is the main cause of erratic percentage readings after a swap.

Why the Catalyst 3622A reports wrong battery percentage after a cell swap

The phone's fuel gauge IC stores a learned discharge curve calibrated to the old cell. When a new cell goes in, that stored curve no longer matches actual cell chemistry. The IC reads voltage and estimates capacity against wrong reference data, so the percentage display drifts. One full discharge from 100% down to automatic shutoff — then a complete charge to 100% — forces the coulomb counter to reset and relearn the new cell's curve. After that cycle, percentage accuracy returns to normal.

Sudden shutdown at 20–30% on the new cell

This happens when the cell voltage drops sharply under modem or display load before the fuel gauge registers a low reading — a voltage cliff the OS doesn't catch in time. The phone shuts down to protect the cell, even though the percentage shown looks safe. The root cause is the uncalibrated fuel gauge overestimating remaining capacity at mid-range. Run the recalibration cycle described above; if shutdowns continue after two full cycles, check that the replacement cell seated flush with no bent connector pins. After recalibration the cutoff threshold should track to 3.4V under load.