About this replacement
Ezviz DL20VS / DL30VS — 3.7V Li-ion Replacement Battery (BL-DL-01B)
This is a 3.7V 5700mAh Li-ion replacement battery for the Ezviz DL20VS and DL30VS smart door locks. It replaces OEM part number BL-DL-01B. The battery powers the motorised bolt, keypad, Bluetooth radio, and NFC or keycard reader in both lock models.
- DL20VS and DL30VS compatibility: Both locks run on the same 3.7V single-cell architecture and use the same BL-DL-01B form factor. The BMS connector and physical dimensions — 75.30 × 44.00 × 21.20mm — are identical across the series, so one battery covers both.
- Bench tested on actual hardware: We ran this battery through lock cycling on a DL20VS unit. The BMS held stable across motor-start current spikes during bolt engagement and maintained communication with the lock's low-battery detection circuit without false alerts.
- Post-swap access check: After fitting this battery, test every access method — keypad code, Bluetooth app, and keycard or fingerprint if fitted — before closing the door. The DL20VS and DL30VS run a firmware handshake on first power-up after a battery interruption, and some access methods stay locked out until that handshake completes.
Why the DL20VS shows low battery immediately after a fresh install
The DL20VS samples battery voltage within seconds of power-up to set its low-battery threshold. If the replacement battery has been sitting in storage at reduced voltage, the lock can flag it as low before any real discharge has occurred. This is a voltage-at-rest reading, not a capacity reading. Leaving the lock powered for 15–20 minutes after install lets the BMS recalibrate its state-of-charge estimate against actual loaded voltage, and the warning clears.
Bluetooth not connecting to the Ezviz app after battery replacement
Cutting power to the DL20VS or DL30VS resets the Bluetooth stack, and some firmware versions drop the existing app pairing rather than restoring it automatically. Open the Ezviz app, navigate to the lock's device settings, and trigger a re-pair from there — the lock does not need a full factory reset. If the app shows the lock as offline after re-pairing, check that the lock firmware is up to date, as earlier builds had a known reconnection bug that required a firmware push to resolve. Confirm the battery is seated fully and reading above 3.6V before troubleshooting the app side.