Juniper Allegro 2 Replacement Battery 3.7V 10400mAh

Juniper Allegro 2 / Archer 2 — 3.7V Li-ion Replacement Battery (2EXL7431-001)

This 3.7V, 10400mAh Li-ion battery replaces OEM part 2EXL7431-001 in the Juniper Allegro 2 and Archer 2 mobile data collection handhelds. It also fits the Systems AR2 and Systems AG2 variants. Built to the same voltage and capacity spec as the original pack, it slots into the same battery bay without modification.

• Allegro 2 and Archer 2 platform fit: Both handhelds share the same battery bay dimensions, connector pinout, and BMS communication protocol. The same 3.7V cell stack and 38.48Wh energy rating cover both units, which is why one part number — 2EXL7431-001 — spans the entire platform line.
• Bench tested on actual hardware: We ran this pack through the Allegro 2 charge cycle and confirmed the BMS handshake completes correctly. The protection circuit tripped at the expected low-voltage threshold and recovered cleanly on reconnect. No charge fault codes were logged.
• Field deployment prep: After fitting this pack, run a full calibration cycle through the instrument menu before heading out. The Allegro 2 maps battery state during that calibration pass — skip it and the device will throw premature low-battery warnings well before the pack is actually depleted.

BMS lockout after the Allegro 2 sat unused in a carry case for months

Li-ion packs left discharged for extended periods can drop below the BMS recovery threshold — typically around 2.5V per cell. When this happens, the protection circuit locks out and the device shows no charge activity at all. The fix is to apply a slow trickle charge directly to the pack using a compatible Li-ion charger set to a low current, which nudges the cell voltage above the recovery floor. Once the BMS detects voltage above that threshold, it re-enables the charge path and normal charging resumes. If the pack was stored below 2.0V per cell for an extended period, cell recovery may be incomplete.

Allegro 2 shuts down mid-logging session despite showing a charged battery

This usually happens when sustained sensor or GPS load pulls the pack voltage low enough to trip the BMS undervoltage cutoff — even if the displayed percentage looked fine moments before. The fuel gauge on the Allegro 2 reads a resting voltage, not the voltage under active draw, so sag under load can be much steeper than the display suggests. If shutdowns happen consistently during long GPS logging or sensor-active sessions, check the battery terminal voltage under load with a multimeter — a healthy cell should hold above 3.4V per cell under draw. A pack that sags below 3.0V per cell under moderate load needs replacing regardless of resting state percentage.