Pentax PA-A867-NG 9.6V Replacement Battery 4500mAh Ni-MH

PM PA-A867-NG — 9.6V Ni-MH Replacement Battery

This is a 9.6V, 4500mAh Ni-MH replacement battery for the PM PA-A867-NG surveying and data collection instrument. It slots into the same bay as the original pack and runs at the same voltage rail. Capacity is sourced from product data at 43.2Wh — not interpolated from a third-party source.

• PA-A867-NG platform fit: The PA-A867-NG uses a fixed 9.6V Ni-MH format with a specific connector orientation and cell count — eight 1.2V cells in series. Any deviation in cell count changes the terminal voltage and causes the instrument's voltage comparator to flag a low-battery condition even on a full charge.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on a Ni-MH compatible analyser, confirmed BMS handshake, and verified the cell block held voltage under a sustained 1A draw. No mid-discharge dropout was observed across three consecutive cycles.
• First-cycle calibration on the PA-A867-NG: After installing this pack, run a full calibration cycle through the instrument menu before heading into the field. The PA-A867-NG maps battery state during that routine — skip it and the low-battery warning will trigger early on the first measurement session, even though the pack is not depleted.

BMS lockout after the PA-A867-NG pack sat unused for months

Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. A pack stored in a carry case for several months can drop below the BMS recovery threshold — typically around 7V for a 9.6V eight-cell pack. When the instrument sees that voltage on insertion, it may refuse to charge or power on at all. The fix is to apply a controlled trickle charge at 0.1C using a standalone Ni-MH charger until the pack reaches approximately 8.5V, then transfer to the instrument's onboard charger to complete the cycle.

Readings drifting or resetting mid-session during active logging

When the PA-A867-NG sustains a sensor or probe load over an extended logging session, the combined draw can cause a momentary voltage dropout across the cell block. That dropout — even if brief — is enough for the instrument's processor to register a power anomaly and reset the active session. This is distinct from a dead battery; the pack may still show adequate charge on the indicator. Check that cell voltage under load stays above 1.0V per cell (8.0V total) — if it drops below that threshold during logging, the cells have degraded past serviceable capacity and the pack needs replacement.