Ultralast DL-25 Smart Lock Replacement Battery 9V 2700mAh

Ultralast DL-25 / HTLUL10 — 9V Alkaline Replacement Battery

This Ultralast 9V alkaline battery delivers 2700mAh (24.3Wh) to electronic door locks. It fits the DL-25 and HTLUL10 lock models. The flat 103.05 x 58.10 x 15.76mm form factor slots directly into the battery compartment on both units.

• DL-25 and HTLUL10 platform: Both locks run on a single 9V cell that powers the keypad controller, motor driver, and Bluetooth radio from one voltage rail. Swapping to an undersized or off-spec cell drops the rail and causes inconsistent motor response or radio dropouts.
• Bench tested on actual hardware: We cycled this cell through repeated lock-and-unlock sequences on the DL-25. The BMS on both locks held stable voltage through motor-start draw spikes without tripping a low-voltage cutoff.
• Post-swap access check: After fitting this battery, test every access method — keypad code, Bluetooth app, and any keycards — before closing the door. Some lock firmware runs a handshake sequence after power interruption; the lock will not accept all credentials until that sequence completes.

Why the DL-25 motor slows or stalls before the low-battery indicator fires

The DL-25 keypad triggers a low-battery alert at a fixed voltage threshold, but the latch motor draws a short high-current spike on every cycle. An aging or low-capacity 9V cell can sustain the keypad and radio at resting voltage while sagging below the motor's minimum during that spike. The result is a slow or stalled bolt — before any warning appears on the keypad. Replacing the cell at the first sign of sluggish motor movement, rather than waiting for the LED alert, prevents a locked-out door.

Lock beeping low-battery signal immediately after a fresh battery is fitted

This usually means the lock read the cell's open-circuit voltage before the battery settled under load, or polarity is reversed in the compartment. Pull the battery out, check the orientation against the compartment markings, and reinsert firmly. If the beeping continues, confirm the cell reads at least 9V on a multimeter before reinsertion. A reading below 8.5V at rest indicates a discharged or faulty cell — replace it.