TPI A007 HXG-2D Survey Instrument Replacement Battery 3.6V 2000mAh

TPI HXG-2D Series — 3.6V Ni-MH Replacement Battery (A007)

This is a 3.6V, 2000mAh Ni-MH battery pack for the TPI HXG-2D and related instruments including the 712 and 709R. It replaces OEM part numbers A007, 160AAH3BML, and A774. The pack fits the HXG-2D combustible gas leak detector and compatible survey and test instruments in the same family.

• HXG-2D family compatibility: These models share a common 3.6V three-cell NiMH voltage rail, the same physical connector footprint, and a passive BMS interface — no active handshake required, which means the pack slots in without firmware negotiation.
• Bench tested on actual hardware: We ran this pack through power-on sequencing and sensor initialisation cycles on the HXG-2D platform. The BMS held stable through the current spike at probe power-up without tripping into protection mode.
• Post-install calibration cycle: After fitting this pack, run a full calibration cycle through the instrument menu before taking it into the field. The HXG-2D maps battery state during calibration — skip this and the instrument will throw premature low-battery warnings on your first measurement session, even with a fully charged pack.

Why the HXG-2D shuts down at probe sensor initialisation

When the HXG-2D powers up its gas sensor, there is a short but sharp current draw as the probe heater element reaches operating temperature. An aged or partially discharged NiMH pack can sag below the instrument's cutoff threshold during this spike — not because the pack is empty, but because internal resistance has increased enough to cause a voltage dip. A fresh pack with low internal resistance handles the spike without dropping out. If the shutdown happens every time at the same point in the boot sequence, that is the cause.

Pack will not charge after months sitting unused in a carry case

NiMH cells self-discharge over time, and after an extended storage period the pack voltage can fall low enough that the charger circuit refuses to begin a charge cycle — it reads the pack as a fault condition rather than a depleted battery. This is a BMS sleep state, not a dead pack. To recover it, connect the instrument to its charger and leave it for 30–60 minutes without interruption — some chargers will trickle a small recovery current before switching to full charge. If the charge LED stays off after that window, check the pack voltage directly at the terminals; a reading below 2.4V means the cells need a forced low-current recovery charge before the standard cycle will take.