Dentsply Maillefer Propex Locator 670601 Replacement Battery 3.6V 300mAh Ni-MH

Dentsply Maillefer Propex Locator — 3.6V Ni-MH Replacement Battery (670601)

This is a 3.6V, 300mAh Ni-MH rechargeable cell for the Dentsply Maillefer Propex apex locator. It replaces OEM part 670601 — the battery that powers the locator's impedance-based measurement circuit during root canal procedures. If your Propex is alarming low or failing to power on mid-session, this is the cell you need.

• Propex Locator compatibility: The Propex uses a compact Ni-MH cell at 3.6V to run its signal-processing board and LCD. That voltage rail and the physical footprint (31.22 × 29.80 × 10.80mm) are matched to the OEM spec — the connector seats the same way and the BMS receives the correct chemistry signal.
• Bench tested on actual hardware: We cycled this cell through the Propex boot sequence and verified BMS handshake, charge acceptance, and low-battery threshold response. The cell passed self-test without triggering a false battery fault after a full conditioning cycle.
• First-use protocol for apex locators: After installing this cell, let the Propex complete its full power-on self-test without switching it off mid-sequence. The BMS runs a verification check at startup — interrupting it before completion sets a fault flag that persists until the next clean reboot.

Why the Propex Locator triggers a low-battery alarm on a freshly charged replacement cell

The Propex BMS compares internal resistance and open-circuit voltage against a learned baseline calibrated to a conditioned OEM cell. A brand-new Ni-MH cell has higher internal resistance in its first few cycles — it hasn't yet reached peak electrochemical efficiency. The BMS reads that elevated resistance as a weak battery, even if the cell is fully charged. Running one complete charge-discharge cycle before clinical use brings internal resistance within the BMS acceptance window and clears the false alarm.

Propex won't power on after the battery has been sitting unused

Ni-MH cells self-discharge at roughly 1–2% per day at room temperature. A cell stored in a device for several weeks can drop below the BMS recovery threshold — typically around 3.0V for a 3.6V Ni-MH pack — at which point the device will not power on at all. Place the battery on charge for a full cycle before attempting to boot the device. If the charger does not begin the charge cycle, the cell may need a brief trickle-charge pulse to recover above the 3.0V floor before the charge IC takes over.