24V Besam 505186-BB Automatic Door Lock Replacement Battery

Besam automatische Turoffnung EMC Series — 24V Ni-MH Replacement Battery (505186-BB)

This is a 24V 300mAh Ni-MH replacement battery for Besam automatic door opening systems. It fits the automatische Turoffnung EMC, EMCM, EU-EUD, and related EMC-series operators. The battery backs up the electronic door lock mechanism so the door operator can function during a power interruption.

• EMC and EMCM series compatibility: These models share the same 24V battery bay, connector pinout, and BMS handshake protocol. The 505186-BB also cross-references as OEM part numbers 654699, 41A017CA00001, and 06000142 — all drawing from the same 24V Ni-MH cell stack.
• Bench tested on actual hardware: We cycled this battery through charge, standby, and simulated power-fail events on an EMC-series operator. The BMS accepted the cell stack without fault codes, held float charge correctly, and released cleanly on simulated mains dropout.
• Post-swap access method verification: After fitting this battery, cycle power to the door operator completely before closing the door. Some EMC-series units require a full controller reboot to re-establish the BMS handshake — skipping this step can leave the lock unresponsive to access credentials until the reboot completes.

Why the EMC operator shows a fault LED immediately after battery replacement

Ni-MH cells ship in a partial state of charge, typically between 40–60% of rated capacity. The EMC controller measures open-circuit voltage on startup and flags a fault if the reading falls below its internal threshold, even with a brand-new battery installed. This is a controller-side check, not a battery defect. Run a full charge cycle via the operator's onboard charger before placing the door back into service — the fault LED will clear once the pack reaches approximately 26–27V under charge.

Door operator not responding to access credentials after battery swap

Removing the battery cuts power to the controller board, which clears its working state. On EMC-series units, the firmware must complete an initialisation sequence before the access control logic goes live again. If credentials are tested before that sequence finishes, the lock will not respond — this is not a wiring fault or a battery issue. Remove the battery, wait 10 seconds, refit it, allow the operator 30 seconds to boot fully, then test access at 24V steady-state on the battery terminals.