About this replacement
Ring 5UM5E5 / Video Doorbell 2nd Generation — 3.8V Li-Polymer Replacement Battery (S2)
This 3.8V, 5200mAh Li-Polymer battery replaces the OEM S2 cell in Ring model 5UM5E5 and Video Doorbell 2nd Generation wireless security cameras. The original cell degrades after repeated charge cycles, causing the camera to drop offline or stop recording motion events. This replacement restores the voltage rail the device needs to stay connected and active.
- 5UM5E5 and Video Doorbell 2nd Generation fit: Both devices share the same S2 cell format, 3.8V nominal rail, and physical connector. The BMS handshake and charge profile are identical across the two units, so the same replacement cell works in either.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the 5UM5E5 platform. The BMS accepted the new cell without fault codes, and the voltage held stable through simulated motion-trigger current spikes from the IR LED and processor combined draw.
- First-install power cycle: After fitting the new cell, power cycle the camera once through the Ring app. The firmware must register the new cell before motion recording logs correctly to cloud storage — skipping this step can cause missed event clips even when the camera appears online.
Camera going offline in the Ring app after battery swap
Swapping the cell clears the active firmware session between the camera and the Ring cloud. The device loses its session token during the power interruption and does not always re-register automatically on first boot. This shows up as the camera appearing offline or unresponsive in the app even though the LED indicates normal status. Open the Ring app, navigate to Device Health, and run a reconnect — the camera will re-authenticate and come back online within 60 seconds.
App showing 0% or incorrect battery percentage after installing a new cell
Ring cameras use a voltage-threshold indicator, not a fuel gauge IC. When a new cell is installed, the firmware has no prior voltage history to calibrate against, so it defaults to 0% or displays an inaccurate figure. One full charge-to-discharge cycle lets the firmware map the cell's actual voltage curve and display the correct percentage. Charge the camera to 100% via the Ring app charge indicator, then let it run normally — the percentage will read accurately from the next charge cycle onward, stabilising around 4.2V at full charge.