Theis TPL-H 6V Ni-MH Compatible Battery 3000mAh N04-05.02

Theis TPL-H / TPL-2N — 6V Ni-MH Replacement Battery (N04-05.02)

This is a 6V, 3000mAh Ni-MH replacement battery for the Theis TPL-H and TPL-2N surveying and diagnostic instruments. It replaces OEM part number N04-05.02. The battery slots into the instrument's battery compartment and powers sustained sensor and probe operation in the field.

• TPL-H and TPL-2N compatibility: Both models share the same 6V battery rail, connector pinout, and BMS handshake protocol — that is why one pack covers both. The cell arrangement and discharge curve match what each instrument's power management circuit expects during measurement cycles.
• Bench tested on actual hardware: We ran this pack through probe initialisation and sustained logging loads on the bench. The BMS held voltage without tripping during the current spike at probe power-up, and cell balance stayed consistent across multiple discharge cycles.
• Post-install calibration cycle: After fitting this battery, run a full calibration cycle through the instrument menu before field deployment. The TPL-H maps battery state during calibration — skipping this step causes premature low-battery warnings to appear during your first measurement session, even with a full charge.

BMS lockout after the TPL-H sat unused in a carry case for months

Ni-MH cells self-discharge at roughly 1–3% per day at room temperature. After several months in storage, the pack voltage can drop below the threshold the instrument's BMS needs to initiate a charge cycle. When this happens, the charger appears to do nothing — no charge indicator, no response. The fix is to apply a low-current recovery charge directly to the pack terminals at around 0.1C (300mA) for 20–30 minutes to bring the cell voltage up to the recovery threshold before using the standard charger. Once the pack reads above approximately 5.4V, normal charging resumes without issue.

Readings drifting or logging session resetting mid-survey

Sustained sensor load draws more current than standby — on the TPL-H, running multiple probes simultaneously can pull enough current to cause a brief voltage dropout across the cells. If the battery has partial capacity fade from shallow cycling, that dropout crosses the instrument's reset threshold and the logging session clears. Ni-MH cells degrade faster when repeatedly discharged only 20–30% before recharging; the usable voltage window narrows, and the instrument sees an apparent cutoff sooner than the state-of-charge indicator suggests. Allow the pack to discharge to at least 50% before recharging to keep cell capacity in a healthy range and reduce mid-session dropout events.