I-Mate UF553450U PDA-L Compatible Battery 3.7V 1100mAh

I-Mate PDA-L — 3.7V Li-ion Replacement Battery (UF553450U)

This is a 3.7V, 1100mAh Li-ion battery for the I-Mate PDA-L and PDAL. It replaces OEM parts UF553450U, UF553450Z, XWD051087, and XWD033454. The PDA-L is a Windows Mobile smartphone-PDA hybrid from the mid-2000s — voice calls, email, and basic computing in one unit.

• PDA-L and PDAL fit: Both model designations share the same battery bay geometry, connector pinout, and BMS handshake protocol — the cell and protection circuit are identical across both variants.
• Bench tested on actual hardware: We ran the cell through charge and discharge cycles on the PDA-L platform. The BMS accepted the full charge cycle without tripping overcurrent protection, and the fuel gauge IC engaged correctly after the first full discharge.
• Fuel gauge recalibration on first use: After installing this cell, disable any sync or active data connections and run one full discharge before recharging. The PDA-L fuel gauge IC is calibrated against the old cell's discharge curve — one complete cycle lets it recalibrate against the new cell's actual capacity before reporting accurate percentages.

Why the PDA-L shuts down suddenly at 20–30% remaining

The PDA-L draws a sharp current spike when the modem transmits or the backlight fires at full brightness. An aged or freshly installed cell with an uncalibrated fuel gauge can hit a voltage cliff — internal resistance causes the cell voltage to sag below the BMS cutoff threshold faster than the reported percentage suggests. The device interprets this as a fault and shuts down even though the fuel gauge still shows charge remaining. After one full discharge-charge cycle, the fuel gauge IC maps the new cell's actual voltage-to-capacity curve, and the cutoff point aligns with the real remaining charge.

Device warm near the battery compartment during first charge

A new Li-ion cell has slightly higher impedance than a broken-in cell. During the first charge, the charge IC pushes current into higher resistance, which generates more heat than you'd see from a well-cycled battery. This is normal and should taper off after the first two full cycles as the cell's internal impedance drops. If the device stays warm beyond two full charge cycles, check that the battery contacts are fully seated — a partially connected cell forces the charge IC to work harder to maintain current flow.