I-Mate PDAG Replacement Battery 3.7V 1500mAh US454261A8T

I-Mate PDAG / GC588 / X800D — 3.7V Li-Polymer Replacement Battery (US454261A8T)

This 3.7V, 1500mAh lithium-polymer cell replaces the original battery in the I-Mate PDAG, PDA-G, GC588, and X800D Windows Mobile PDA phones. It matches the OEM part number US454261A8T and fits the same battery bay without modification. Voltage and capacity are spec-matched to the original to keep the device's charge IC operating within its programmed thresholds.

• PDAG, PDA-G, GC588, and X800D compatibility: These four models share the same battery bay dimensions, 3.7V nominal voltage rail, and connector pinout, so a single cell covers the full group. The BMS handshake expectations are identical across all four variants.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the PDAG platform and confirmed the charge IC accepted the new cell without triggering an overcurrent fault. The BMS held the cutoff at the expected low-voltage threshold with no premature trip.
• Fuel gauge recalibration on first use: After installing this cell, run one complete discharge down to automatic shutdown, then charge uninterrupted to 100% before resuming normal use. The PDAG's fuel gauge IC is calibrated to the old cell's discharge curve — skipping this cycle causes the OS to report inaccurate percentages for days.

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

The PDAG's fuel gauge IC stores a discharge curve from the previous cell. When a new cell with a different internal impedance is installed, the IC's voltage-to-percentage mapping goes off. The phone reads 25% remaining but the actual cell voltage under GSM radio load drops below 3.4V, triggering a hard shutdown. Running one full discharge-charge cycle lets the coulomb counter reset its endpoint registers against the new cell's actual curve, and the shutdowns stop.

Device will not power on after sitting in storage with a depleted battery

Lithium-polymer cells that self-discharge below roughly 2.5V trigger the BMS protection circuit, which locks out all output to prevent cell damage. The PDAG will show nothing on screen and will not respond to the power button. Connect the device to a charger and leave it for 15–20 minutes without pressing anything — the charge IC trickle-charges the cell back above the BMS re-enable threshold, typically around 2.8V, at which point the BMS releases and the device will power on normally.