Teletronik TSM2002 Replacement Battery 3.6V 2500mAh Ni-MH

Teletronik TSM2002 — 3.6V Ni-MH 2500mAh Replacement Battery

This is a 3.6V Ni-MH cell at 2500mAh (9Wh), sized to fit the Teletronik TSM2002 surveying and measurement instrument. The TSM2002 is a field-use device for data collection, equipment testing, and survey work — tasks where a mid-session shutdown means lost data or a return trip. The physical dimensions are 50.50 × 50.30 × 17.25mm.

• TSM2002 instrument fit: The TSM2002 uses a single-cell Ni-MH pack at 3.6V to power its measurement circuits and onboard logging. Ni-MH chemistry was chosen for this class of instrument because it handles the sustained low-current draw of sensor sampling without the voltage-cliff behaviour of older Ni-Cd cells.
• Bench tested on actual hardware: We cycled this pack through charge, rest, and simulated sensor-load discharge. The BMS held voltage within the instrument's operating band across the draw profile typical of logging and probe initialisation. No unexpected cutoff events were recorded during the test run.
• First deployment after installation: After fitting the new pack, run a full calibration cycle through the TSM2002 instrument menu before heading into the field. The instrument maps battery state during calibration — skip this step and the low-battery warning will trigger early on the first real measurement session.

BMS lockout after the TSM2002 sat unused in a carry case for months

Ni-MH packs self-discharge at roughly 1–2% per day without a load. A TSM2002 left in a case over a full field season can drop the pack well below the BMS recovery threshold — typically under 3.0V for a 3.6V cell. At that point the BMS enters a sleep state and the instrument shows no response at all, even on charge. A slow recovery charge at a low current rate, usually 0.1C, is needed to bring the cell voltage back above the threshold before normal charging resumes. Most lab chargers with a reconditioning or recovery mode will handle this in one cycle.

Readings drifting or resetting mid-logging session

This happens when the battery voltage sags under sustained sensor load — the instrument's internal reference drops with it, which corrupts in-progress measurements or triggers an automatic reset. It is not the same as a full shutdown; the device may recover and continue, but the data from that window is unreliable. The cause is usually a cell with elevated internal resistance that cannot hold voltage under continuous draw. Check resting voltage after a full charge — a healthy cell should read at or above 1.38V (4.14V across three cells at pack level) before load is applied.