PowerSonic A6090-2 Emergency Light Replacement Battery 7.2V 2000mAh

PowerSonic A6090-2 — 7.2V Ni-MH Replacement Battery (OSA279)

This is a 7.2V, 2000mAh Ni-MH replacement battery for the PowerSonic A6090-2 emergency lighting unit. It slots into the fitting in place of the original cell pack and restores the unit's ability to illuminate during a mains failure. Correct voltage and chemistry match ensures the onboard charge controller accepts the new cell without faulting.

• A6090-2 cell compatibility: The A6090-2 uses a 7.2V Ni-MH pack because its charge controller is calibrated to the float and trickle voltage curves specific to that chemistry. Swapping to a different chemistry — even at the same voltage — trips the controller into a permanent fault state.
• Bench tested on actual hardware: We ran this cell through a full mains-failure simulation. The BMS accepted charge within the expected window, and the unit held load through a complete test cycle without voltage sag triggering an early cutoff.
• First test cycle after installation: Within 24 hours of fitting, hold the test button for the full rated duration. This lets the charge controller register the new cell's capacity and gives the cell one conditioning cycle before your next scheduled compliance inspection.

Charge indicator staying red after new battery installation

A freshly installed Ni-MH cell can sit at a resting voltage that falls outside the charge controller's float acceptance window after months in storage. The controller reads this as a fault condition rather than a low cell and holds the red LED. Leave the unit on mains power for a full 24-hour charge cycle without triggering a test. If the LED has not shifted to green after 24 hours, check the cell connector seating — a partially engaged connector causes the same symptom and is the most common installation error on this fitting.

Emergency light failing its duration test after battery replacement

A new Ni-MH cell does not reach rated capacity on its first activation. The electrochemical plates need one full charge-discharge cycle before they deliver the full 2000mAh the pack is rated for. If the unit cuts out early during a duration test run immediately after fitting, that is not a faulty cell — it is an unconditioned one. Run one complete manual test cycle, recharge for 24 hours, then retest. The second test result is the one that reflects true cell capacity.