Keysight U5752A Thermal Camera Replacement Battery 7.4V 2600mAh

Keysight U5752A / U5855A Series — 7.4V Li-ion Replacement Battery (UR-123 / 5190-3540)

This is a 7.4V 2600mAh lithium-ion battery for the Keysight U5752A, U5855, and U5855A thermal imaging cameras. It slots into the same bay as the original and carries the same OEM part numbers: UR-123 and 5190-3540. Capacity figures come from product data, not estimates.

• U5752A, U5855, and U5855A compatibility: These three models share the same 7.4V battery bay, connector pinout, and BMS handshake protocol. The camera's power management circuit reads cell state-of-charge through the same communication line across all three, so one battery pack covers the whole group.
• Bench tested on actual hardware: We ran this pack under combined display and thermal detector load — the draw profile thermal cameras produce during active scanning. The BMS held cutoff thresholds in range and did not trip under the startup surge the detector heating element pulls on cold power-on.
• Detector stabilisation after swap: After fitting a fresh battery, allow the camera to run for at least 60 seconds before taking measurements. The thermal detector requires the internal electronics to reach a stable temperature for accurate baseline calibration — readings taken immediately after power-on will drift.

Thermal camera shutting down mid-inspection on a new battery

The U5752A and U5855A draw current from two simultaneous loads: the LCD display and the microbolometer detector heating element. During an active scan in a hot environment, the combined draw can spike above what the BMS expects from normal operation. If the pack voltage sags below the BMS protection threshold under that spike — even briefly — the camera cuts power to protect the cells. This is not a faulty battery; it is the protection circuit doing its job. Let the camera cool for two minutes, reinsert the battery, and power on in a cooler area to confirm the pack is healthy before returning to the inspection site.

Thermal image accuracy degrading before the battery indicator shows low

The microbolometer in these cameras is voltage-sensitive. As cell voltage drops toward the lower half of its discharge curve — typically below 7.0V under load — detector bias voltage becomes less stable, and small thermal differences in the scene become harder to resolve accurately. The camera's fuel gauge reads state-of-charge from a stored model, not live cell voltage under load, so it can still show two bars while accuracy has already dropped. If readings look soft or noise increases before the low-battery warning appears, swap the battery and compare — a fresh pack at full voltage will show the difference immediately.