Extech i5 Infrared Camera Compatible Battery 3.7V 2200mAh

Extech i5 Infrared Camera — 3.7V Li-ion Replacement Battery (1950986)

This is a 3.7V, 2200mAh Li-ion replacement battery for the Extech i5 and Flir i7 infrared cameras. It fits directly into the camera body and restores full function to the thermal imaging system. Capacity matches the original at 2200mAh (8.14Wh).

• Extech i5 and Flir i7 compatibility: Both cameras share the same 3.7V single-cell architecture, connector pinout, and BMS handshake protocol — the same pack powers either unit without modification.
• Bench tested on actual hardware: We ran this pack on an i5 body under continuous detector and display load. The BMS held the output rail steady above 3.5V through discharge and tripped the protection circuit cleanly at the low-voltage threshold without causing a hard lock.
• Detector stabilisation after swap: After fitting a fresh battery, power the camera on and wait a full 60 seconds before taking any measurements. The microbolometer detector needs that window to reach thermal equilibrium with the internal electronics — readings taken before stabilisation will drift and cannot be trusted.

Thermal accuracy affected at low battery on the Extech i5

The i5's microbolometer runs a continuous internal calibration loop that depends on a stable voltage supply. When the cell drops below roughly 3.5V under load, the calibration circuit starts seeing supply noise and the detector baseline shifts. Temperature readings can skew by several degrees before the low-battery icon even appears on screen. Swapping the battery — not just recharging — is the fix once this pattern starts repeating on an aged cell.

Camera warm to the touch during extended inspections

The i5 runs two significant heat sources simultaneously: the display backlight and the detector's own heating element, which keeps the microbolometer at a controlled operating temperature. That combined draw generates real internal heat, particularly during inspections longer than 30 minutes. The battery housing sits adjacent to both components, so warmth in that area is expected — it is not a fault. If the housing becomes hot rather than warm, check that the ventilation slots on the rear panel are not blocked by a case or pouch.