About this replacement
Eufy 2C Pro Indoor Camera — 3.7V Li-ion Replacement Battery (SW18650 34M 2P)
This 3.7V Li-ion cell at 6700mAh (24.79Wh) replaces the original battery in the Eufy 2C Pro indoor camera and several 2C series variants. It fits the 2C Security Camera, 2C Wireless Door Camera, and 2K Wireless Door Camera, among others. All share the same SW18650 34M 2P cell configuration and connector layout.
- 2C series cell compatibility: These models run the same 3.7V power rail and use identical BMS handshake logic. Swapping cells between 2C variants works because the protection circuit monitors voltage thresholds — not device-specific firmware tokens tied to the cell itself.
- Bench tested on actual hardware: We ran this cell through a full charge cycle and triggered repeated motion events on the 2C Pro. The BMS handled the combined IR LED and processor current spike without tripping cutoff, and cloud recording logged correctly throughout.
- First-install power cycle: After fitting the new cell, power cycle the camera once through the Eufy app. The firmware must re-register the cell before motion recording logs reliably to cloud storage — skipping this step can cause the first few motion events to drop silently.
Camera going offline in the app after battery installation
When you swap the cell on a 2C series camera, the device loses its active session token. The Eufy app treats the power interruption like a first-time boot. The camera may show as offline even if the LED status light looks normal. Open the app, navigate to device settings, and run a restart or re-add the device to force a fresh token handshake.
App reporting 0% or frozen battery percentage after swap
The 2C Pro uses a voltage-threshold indicator — not a fuel gauge IC. After a cell swap, the firmware has no stored voltage history to reference, so it defaults to 0% or stalls until it observes a full charge-to-discharge cycle. Charge the camera to 100%, let it run through normal use until the app records a drop, and the percentage display will calibrate. Do not pull the battery mid-cycle — the indicator needs a complete voltage sweep to anchor its thresholds.