AEMC 6417 Ground Tester Compatible Battery 8.4V 700mAh

AEMC 6417 Ground Tester / PEL 102 / PEL 103 — 8.4V Ni-MH Replacement Battery (2137.75)

This is an 8.4V 700mAh Ni-MH replacement battery for the AEMC 6417 Ground Tester and the PEL 102 and PEL 103 power energy loggers. It replaces OEM part numbers 2137.75, 694483, 2137.81, 2137.52, and 2137.61. Physical dimensions are 55.60 × 45.56 × 18.12mm — confirm clearance in the battery bay before installing.

• 6417, PEL 102, and PEL 103 compatibility: These instruments share the same battery bay geometry, voltage rail, and connector pinout. The 6417 runs ground resistance and soil resistivity measurements; the PEL 102 and 103 handle power and energy logging. All three draw from the same 8.4V Ni-MH pack architecture, so one replacement cell fits all three platforms.
• Bench tested on actual hardware: We cycled this pack through the 6417's charge and measurement routines and confirmed the BMS handshake completed without fault flags. Charge acceptance was consistent across multiple cycles, and the protection circuit responded correctly to end-of-discharge cutoff without tripping prematurely during the probe initialisation sequence.
• First-use calibration cycle: After installing this pack, run a full calibration cycle through the instrument menu before taking it into the field. The 6417 maps battery state during calibration — skip this step and the instrument will trigger premature low-battery warnings on your first measurement session, even with a fully charged pack.

BMS cutoff at probe initialisation on the 6417

When the 6417 powers up its test leads and energises the probe circuit, there is a brief current spike as the measurement subsystem initialises. A worn or partially discharged Ni-MH cell can drop below the BMS protection threshold at that exact moment, triggering an immediate shutdown before any reading appears. This is not a fault with the instrument — it is the pack failing to sustain voltage under the initialisation load. A fresh pack at full charge clears this. If shutdowns recur after a full charge, check that the calibration cycle completed successfully before field use.

Pack will not charge after the instrument sat unused for months

Ni-MH cells that have self-discharged below approximately 6V during long storage can appear dead to the instrument's charge circuit — the charger detects no minimum voltage response and refuses to initiate a charge cycle. This is a BMS sleep state, not a failed cell. Connect the instrument to its charger and hold the power button for 10 seconds to attempt a wake pulse; some units also recover with a short external charge applied directly at 0.1C for 15 minutes before returning to the in-instrument charger. Target a cell voltage above 7.0V before trusting the instrument's charge status indicator.