About this replacement
SAG Schlagbaum / Safe-O-Tronic / Safe-O-Pin / Megalock — 6V Alkaline Replacement Battery (3850000.020.000)
This is a 6V 2600mAh alkaline replacement battery for SAG-compatible electronic door lock systems. It fits Schlagbaum, Safe-O-Tronic, Safe-O-Pin, and Megalock lock platforms that reference OEM part numbers 3850000.020.000, DL-51, 198226, or 4LR06. The lock's motorised bolt and access control electronics both draw from this single cell pack.
- Shared platform — four lock lines, one battery: Schlagbaum, Safe-O-Tronic, Safe-O-Pin, and Megalock use the same 6V battery bay and connector layout. The voltage rail and physical footprint (56.85 × 52.60 × 14.30mm) are identical across all four, which is why one SKU covers all of them.
- Bench tested on actual hardware: We ran this battery through repeated lock-cycle sequences and monitored voltage under motor-start draw. The cell pack held above the BMS threshold through full lock and unlock cycles without triggering a low-voltage cutoff.
- Post-swap access method verification: After fitting the new battery, test every access method — keypad, Bluetooth, keycard — before closing the door. Some Schlagbaum-platform locks execute a firmware handshake on power restoration that must complete fully before all access credentials are accepted.
Low battery warning persisting immediately after a fresh battery install
Some Schlagbaum-platform locks read voltage during the first motor cycle after power-on, not at rest. If the battery sat in storage, its open-circuit voltage may read correctly, but the first motor-start draw causes a voltage sag that the lock interprets as a depleted cell. This is more likely with batteries stored below 50% state-of-charge. Confirm the replacement battery is genuinely fresh stock and check that the cell contacts inside the bay are clean — oxidised contacts add resistance and amplify voltage sag under load.
Bluetooth not reconnecting to the lock app after battery replacement
Cutting power to the lock clears the active Bluetooth session, and some lock firmware versions do not automatically re-advertise after a cold-start. Open the lock's companion app and force a manual scan rather than waiting for auto-discovery. If the lock still doesn't appear, remove the battery for 10 seconds, reinsert it, then scan again within 30 seconds while the firmware completes its initialisation sequence. The lock should appear at approximately 6.0V open-circuit on a fresh alkaline pack.