About this replacement
Sonel KT-670 / KT-640 / KT-560 — 10.8V Li-ion Replacement Battery (WAAKU18)
This is a 10.8V 3400mAh Li-ion replacement for the Sonel WAAKU18 battery pack. It fits the KT-670, KT-640, and KT-560 thermal imaging cameras. Swap it in when the original pack no longer holds charge through a full inspection job.
- KT-670 / KT-640 / KT-560 compatibility: All three cameras run the same 10.8V bus and use the same WAAKU18 form factor with an identical connector and BMS communication protocol — one battery covers the whole platform.
- Bench tested on actual hardware: We ran this pack under combined display and thermal detector load. The BMS held voltage above the cutoff threshold through continuous imaging cycles and did not trip on the detector heating element draw that typically spikes at startup.
- Detector warm-up protocol: After powering on, let the camera stabilise for 60 seconds before starting measurements. The uncooled thermal detector needs the internal electronics to reach a steady temperature — readings taken too early will drift and will not reflect the battery's actual charge state accurately.
Why the KT-670 shuts down mid-inspection on a new battery
The KT-670 draws current from two separate loads simultaneously: the display backlight and the detector's internal heating element. At startup, that combined draw creates a brief current spike that can trip the BMS protection circuit if the pack's internal resistance is too high. A genuine WAAKU18-spec cell handles this surge without dropping below the BMS cutoff threshold. If the camera is shutting down immediately after boot or during the first scan, check that the battery contacts are clean and making solid contact — oxidised terminals add resistance and push the voltage drop past the protection threshold.
Thermal accuracy degrading before the low-battery indicator appears
The thermal detector in the KT-670 is voltage-sensitive. As cell voltage sags under continuous load, the detector's temperature reference can shift before the camera's fuel gauge registers a low-battery warning. This means measurements can drift by several degrees while the battery indicator still shows adequate charge. If readings become inconsistent or calibration warnings appear more frequently, check actual pack voltage with a multimeter — anything below 10.0V under load signals the pack needs replacement, regardless of the on-screen indicator.