FLIR Si124 Thermal Camera Replacement Battery 10.8V 3400mAh

Flir Si124 Series — 10.8V Li-ion Replacement Battery (T912185)

This is a 10.8V, 3400mAh Li-ion replacement battery for the Flir Si124, Si124-PD, and Si124-LD acoustic imaging cameras. It replaces OEM part T912185 and fits the original battery bay without modification. The Si124 platform runs on-site electrical, mechanical, and building surveys where battery failure mid-session means lost data and repeat site visits.

• Si124, Si124-PD, and Si124-LD compatibility: All three variants share the same 10.8V battery bay, connector pinout, and BMS communication protocol. A single cell pack covers the full Si124 product line without adapter or firmware change.
• Bench tested on actual hardware: We ran this pack through power-on, live acoustic imaging, and USB data transfer simultaneously. The BMS held voltage stable across the combined load and did not trip at sensor initialisation.
• First-use calibration on the Si124: After fitting this battery, run a full calibration cycle through the Si124 instrument menu before going to site. The camera maps battery state during calibration — skipping this step causes premature low-battery warnings during your first imaging session, even when the pack is fully charged.

BMS cutoff when the Si124 initialises its acoustic sensor array

When the Si124 powers up, the MEMS microphone array draws a short current spike as each sensor initialises. An aged or low-state-of-charge battery can dip below the BMS undervoltage threshold during this spike, causing an immediate shutdown before the home screen loads. This is a protection trip, not a dead battery. Charge the pack to full before attempting power-on, and the BMS will clear the condition automatically.

Si124 display showing inconsistent battery percentage after swapping to a new pack

The Si124 tracks battery state against a learned voltage curve from the previous cell. A new pack with different internal resistance reads differently at the same open-circuit voltage, so the percentage indicator appears to jump or reset between boots. This is not a fault with the battery or camera. Run two full charge and discharge cycles through normal imaging work, and the camera recalibrates its voltage-to-percentage mapping. After the second cycle, the display stabilises.