Fluke VT04 Replacement Battery 3.7V 2800mAh Li-ion

Fluke VT04 / VT04A Visual IR Thermometer — 3.7V Li-ion Replacement Battery (FLK-VT04)

This 3.7V, 2800mAh Li-ion battery fits the Fluke VT04 and VT04A Visual IR Thermometers. These are handheld thermal imaging cameras used for electrical inspections and building diagnostics in the field. It replaces OEM part numbers FLK-VT04 and 4375741 directly.

• VT04 and VT04A compatibility: Both models share the same battery bay, connector pinout, and BMS handshake protocol. The same 3.7V cell architecture powers the thermal detector array, display, and onboard processing across the entire VT04 platform.
• Bench tested on actual hardware: We ran this cell in a VT04 body under combined detector-heating and display load. The BMS held stable across the full discharge curve without triggering premature cutoff, and charge acceptance matched the OEM charger cycle correctly.
• Field storage between inspection jobs: If the camera will sit unused for more than two weeks, power it down completely rather than leaving it in standby. The thermal detector's heating element draws a small but continuous standby current that accelerates self-discharge faster than most Li-ion devices.

Why the VT04 shuts down mid-inspection on a new or recently charged battery

The VT04 runs three simultaneous power draws: the thermal detector heating element, the visual camera, and the LCD display. When all three activate together — common during a full inspection sweep — peak current demand spikes above what an aged or partially discharged cell can deliver cleanly. The BMS reads the resulting voltage sag as a low-battery condition and trips the protection circuit before the cell is actually empty. A fresh 2800mAh cell with a lower internal resistance handles the combined load without triggering that cutoff.

Thermal readings drifting or losing accuracy before the battery indicator shows low

The VT04's uncooled microbolometer detector is voltage-sensitive. As cell voltage drops below roughly 3.5V under load, the detector's reference calibration circuit starts receiving slightly less stable power, which introduces drift into temperature readings before the device signals a low-battery warning. This is especially noticeable during back-to-back measurements in warm environments where the detector is already working harder. Replacing a battery that's losing capacity — even if it still appears to charge fully — is the correct fix. Check the cell under load: a healthy cell holds above 3.6V during active scanning.