About this replacement
SimpliSafe SSDB3 / Video Doorbell Pro — 3.7V Li-Polymer Replacement Battery (PL502535)
This is a 3.7V 500mAh Li-Polymer cell that replaces part number PL502535 in the SimpliSafe SSDB3 Indoor Camera, Video Doorbell Pro, and U9K-DB3000. At 37.50 × 24.50 × 5.80mm, it matches the original cell's footprint exactly. Capacity is 500mAh (1.85Wh), drawn directly from product specifications.
- SSDB3, Video Doorbell Pro, U9K-DB3000 fit: All three models share the same PL502535 cell format, voltage rail, and connector pinout. The BMS handshake threshold is identical across the platform, so one cell covers all three without modification.
- Bench tested on actual hardware: We cycled this cell through charge and discharge on the SSDB3 platform. The BMS accepted the cell on first connection, held voltage within spec across the charge curve, and protection circuitry tripped correctly at the low-voltage cutoff point.
- Post-install power cycle requirement: After fitting this cell, power cycle the camera once through the SimpliSafe app. The camera's firmware must re-register the new cell before motion events log correctly to cloud storage — skipping this step can cause missed clips even when the battery shows charged.
Camera going offline in the SimpliSafe app after battery swap
Swapping the cell breaks the camera's active session with the SimpliSafe cloud. When power is interrupted and restored, the firmware loses its authentication token and the device drops off the network. The app will show the camera as offline even though the battery is fully charged and the LED is lit. Open the SimpliSafe app, navigate to the device settings for the affected camera, and trigger a reconnect or re-registration — this forces a fresh token handshake and brings the camera back online.
App reporting 0% or frozen percentage after installing a new cell
The SSDB3 uses a voltage-threshold indicator, not a fuel gauge IC — it reads charge state by measuring cell voltage at set intervals rather than tracking coulombs. A fresh cell installed at partial charge can land between thresholds and report 0% or hold a stale percentage from the previous cell. Run one complete charge cycle from the camera's charging port until the indicator confirms full charge, then discharge through normal use. After that full cycle, the voltage thresholds recalibrate and the app reports an accurate percentage.