Cairn Iris 6V Thermal Camera Replacement Battery 4200mAh

Cairn Iris / Vipar 5 / CPI2 — 6V Ni-MH Replacement Battery

This is a 6V 4200mAh Ni-MH replacement battery for the Cairn Iris, Vipar 5, and CPI2 thermal imaging cameras. These handheld thermal scanners are used in building diagnostics, electrical inspections, and preventive maintenance work. When the original pack degrades, thermal accuracy and camera stability go with it — this replacement restores full function.

• Iris, Vipar 5, and CPI2 compatibility: All three models share the same 6V battery rail, physical form factor, and connector pinout. The BMS on each unit expects the same charge profile, so one pack covers all three without modification.
• Bench tested on actual hardware: We ran this pack through charge and discharge cycles while monitoring BMS handshake and cutoff thresholds. The protection circuit responded correctly to both load spikes from the detector heating element and sustained draw from the display backlight.
• Ni-MH conditioning for thermal cameras: Cairn's thermal cameras combine a continuously powered detector element with an active display — this combined draw means the pack cycles more deeply than most handheld devices. Run the battery to the camera's low-battery warning before recharging rather than topping it up after short sessions. Partial cycling accelerates voltage depression in Ni-MH cells faster here than in lower-draw equipment.

Why the Iris shuts down mid-inspection on a charged battery

The Iris draws current simultaneously from the thermal detector heating element and the display backlight. On an aged or cold pack, this combined load causes a brief voltage sag that trips the BMS under-voltage cutoff — even when the battery reads partially charged. Ni-MH cells that have developed voltage depression show a stable resting voltage but collapse under load faster than the BMS anticipates. A fresh 6V 4200mAh pack with lower internal resistance holds voltage above the cutoff threshold through these combined load events.

Thermal image accuracy dropping before the low-battery indicator appears

The thermal detector in the Iris is voltage-sensitive — its calibration baseline drifts when supply voltage falls below the stable operating band. This happens before the battery gauge shows low because the gauge reads resting voltage, not voltage under the detector's active load. The result is thermal readings that look plausible but carry an offset error that worsens as the session continues. If measurements start running inconsistent mid-inspection, check the pack voltage under load with a multimeter — a reading below 5.4V under active camera draw confirms the pack needs replacement.