About this replacement
SAFE-O-KIEFER Safe-O-Pin / Coin Operate Lock — 6V Alkaline Replacement Battery (3850.000.020.000)
This is a 6V 2600mAh alkaline replacement battery for the SAFE-O-KIEFER 3850.000.020.000 electronic door lock system. It fits the Safe-O-Pin Pincode lock and the Coin Operate Lock variant. When the original battery depletes, the lock loses power to its control board and motor — this battery restores full operation.
- Safe-O-Pin and Coin Operate Lock compatibility: Both models share the 3850.000.020.000 battery housing and draw from the same 6V rail to power the keypad logic board, motor drive circuit, and access control firmware. The connector and physical format are identical across both variants.
- Bench tested on actual hardware: We cycled this battery through the lock's motor engagement sequence and keypad polling. The BMS held stable voltage under repeated lock-unlock cycles without triggering a low-battery cutoff prematurely.
- Post-swap access method check: After fitting the new battery, test keypad entry and any secondary access method before closing the door. Some SAFE-O-KIEFER locks run a firmware handshake on first power-up after a battery swap — until that handshake completes, not all access modes will respond.
Lock beeping low-battery warning immediately after new battery install
The 3850.000.020.000 lock samples battery voltage the moment it powers up. If the battery has been in storage for an extended period, its open-circuit voltage may sit just below the lock's detection threshold — triggering an immediate low-battery alert even though the battery is unused. This is a surface-charge issue, not a capacity failure. Remove the battery, wait 10 seconds, reinsert it, and let the lock complete its startup cycle. The reading should stabilise above 5.8V once the lock draws a brief load during initialisation.
Lock motor turns slowly or fails to fully retract the bolt after battery swap
A sluggish bolt retraction usually means the battery voltage is sagging under the motor-start current draw. The lock motor pulls a short high-current spike on each cycle — if internal resistance in the battery is too high, voltage dips enough to cause weak or incomplete bolt movement. Verify the battery is the correct 6V alkaline specification and that polarity is correct in the housing. If the issue persists, check that the battery contacts inside the compartment are clean and making firm contact — oxidised or bent contacts add resistance and compound the voltage drop.