Caterpillar B25 Replacement Battery 3.7V 1450mAh UP073450AL

CATERPILLAR B25 — 3.7V Li-ion Replacement Battery (UP073450AL)

This is a 3.7V, 1450mAh Li-ion cell built to fit the CATERPILLAR B25 ruggedized smartphone. It replaces OEM part UP073450AL and slots into the same battery bay without modification. Voltage and capacity match the original spec exactly.

• B25 compatibility: The B25 uses a single-cell 3.7V Li-ion pack with a proprietary connector and a BMS that handshakes with the phone's charge IC. This cell uses the same connector pinout and communicates correctly with the onboard fuel gauge — the phone recognises it as a valid cell on power-up.
• Bench tested on actual hardware: We cycled this cell through charge and discharge on the B25 platform. The BMS accepted the cell without fault codes, and the charge IC stepped through trickle, constant-current, and constant-voltage phases cleanly.
• Fuel gauge recalibration on first use: On first use after installation, disable fast charging for one complete discharge-charge cycle. This lets the fuel gauge IC map the new cell's discharge curve before high-current charging pushes current into an uncalibrated state — preventing erratic percentage readings from the first charge onward.

Sudden shutdown at 20–30% on the B25 after a cell swap

This happens because the B25's fuel gauge IC is still using the discharge curve of the old, degraded cell. When the new cell hits a voltage point the old curve mapped to 20–30%, the phone interprets it as a low-voltage cutoff and shuts down — even though usable capacity remains. The fix is a full discharge-to-shutoff followed by an uninterrupted charge to 100%, repeated once or twice. After two full cycles, the coulomb counter recalibrates and the percentage readings stabilise.

Phone warm near the battery compartment on the first charge

A new high-impedance cell generates more heat during the initial charge cycle than a broken-in cell does. The B25's charge IC pushes constant current into a cell that hasn't yet settled to its steady-state internal resistance, and that difference shows up as warmth near the battery bay. This is normal for the first one or two cycles and resolves as internal resistance drops. If the phone stays warm beyond the third full charge, check that the cell is seated flat — any gap between the cell and the back cover traps heat.