DOM Protector 4765 Smart Lock Replacement Battery 3.6V 1200mAh

DOM Protector / Winkhaus Blue Chip — 3.6V Li-SOCl2 Replacement Battery (4765)

This is a 3.6V lithium thionyl chloride cell rated at 1200mAh, built for the DOM Protector and Winkhaus Blue Chip electronic door lock systems. It replaces OEM part 4765 and fits the lock's battery compartment at 25.60 × 15.70 × 14.30mm. Li-SOCl2 chemistry is the correct specification for these locks — do not substitute alkaline or standard lithium cells.

• DOM Protector and Winkhaus Blue Chip compatibility: Both locks share the same 3.6V single-cell power architecture and use OEM part 4765. The BMS in each unit is calibrated to the voltage curve of Li-SOCl2 — a different chemistry will misread as low or dead on insertion.
• Bench tested on actual hardware: We cycled this cell through the lock's idle draw and actuation events. The BMS accepted the cell without fault codes, and voltage held steady across multiple motor-drive cycles during testing.
• Post-swap access method verification: After fitting this battery, test every access method — keypad, Bluetooth, and keycard — before closing the door. Some DOM Protector units run a firmware handshake on first power-up that must complete before all credential types are accepted.

Why the DOM Protector shows low battery immediately after a fresh cell install

Li-SOCl2 cells can develop a passivation layer on the anode during storage. This temporarily raises internal resistance and causes the lock's voltage monitor to read the cell as weak — even when it is fully charged. The lock will usually recover within a few actuations as the passivation layer breaks down under load. If the low-battery indicator persists after five or six motor cycles, pull the cell, check polarity, and reinsert to reset the voltage sampling circuit.

Bluetooth not reconnecting to the lock after battery replacement

Cutting power to the lock — even briefly during a battery swap — causes some DOM Protector and Winkhaus Blue Chip units to drop their Bluetooth pairing state. The lock is not faulty; it needs to re-establish the encrypted link with the app. Open the lock's companion app, navigate to device settings, and trigger a re-pair. If the app does not detect the lock, hold the lock's reset button for three seconds to force it into pairing mode, then reconnect.