About this replacement
Flir One Pro / One Pro LT — 3.7V Li-Polymer Replacement Battery (SDL702035)
This 3.7V, 450mAh Li-Polymer cell replaces the SDL702035 and LF602035-02 batteries in the Flir One Pro, One Pro LT, and 435-0012 thermal imaging cameras. It powers the thermal detector, display, and internal electronics that make handheld thermal inspection work possible. Swap it when the original cell no longer holds a usable charge through a full inspection job.
- One Pro and One Pro LT compatibility: Both models share the same connector pinout, BMS handshake protocol, and 3.7V voltage rail, which is why one cell covers the full range. The SDL702035 footprint — 37 × 20 × 7mm — fits the battery bay without modification.
- Bench tested on actual hardware: We ran this cell through charge and discharge cycles on a One Pro unit. The BMS accepted the cell without fault flags, thermal throttling events cleared correctly, and the camera exited standby cleanly at each test cycle.
- Thermal detector warm-up on first power-on: After fitting a new cell, allow the camera to run for at least 60 seconds before taking any measurements. The uncooled thermal detector needs the internal electronics to reach a stable temperature before the baseline calibration is accurate — readings taken immediately after power-on can be off by several degrees.
Thermal camera shutting down mid-inspection on a new battery
The One Pro pulls current from two sources simultaneously — the display backlight and the resistive heating element that keeps the thermal detector at operating temperature. Under combined load, especially in cold ambient conditions where the heater works harder, instantaneous current draw can spike above the BMS protection threshold. A cell with any internal resistance above spec — including a worn original or a poor-quality replacement — trips the overcurrent cutoff before the fuel gauge reads empty. This replacement cell is rated to handle the combined draw without tripping the cutoff under normal operating conditions.
Thermal accuracy degrading before the battery indicator shows low
The uncooled microbolometer in the One Pro is voltage-sensitive. As cell voltage sags under load — typically below 3.5V — the detector's readout electronics lose enough precision that temperature delta accuracy drops before the battery gauge triggers a low-battery warning. This means the camera can appear to have charge remaining while thermal readings are already drifting. If spot temperatures look inconsistent or hot spots seem to shift between frames, check cell voltage directly rather than relying on the indicator. A fully charged cell should read 4.2V at rest; below 3.6V under load, replace or recharge before continuing measurements.