OSI OSA004 4.8V Emergency Light Replacement Battery 2000mAh

OSI OSA004 — 4.8V Ni-MH Replacement Battery for Emergency Lighting

This is a 4.8V 2000mAh Ni-MH replacement cell for OSI emergency lighting units using the OSA004 battery. It restores power-failure activation to emergency exit signs and backup lighting fittings. Fit and connector match the OSA004 specification directly.

• OSA004 platform compatibility: OSI emergency lighting fittings on this platform share a common 4.8V Ni-MH cell format with a matched connector and charge-controller acceptance window. Swapping to a different voltage or chemistry will cause the charge controller to reject the cell or overcharge it.
• Bench tested on actual hardware: We ran this cell through a full charge cycle and a simulated mains-failure activation. The BMS accepted the cell without fault flagging, and load voltage held stable across the discharge curve under the fitting's rated draw.
• First test cycle after installation: Within 24 hours of fitting this battery, hold the test button for the full rated duration. This lets the charge controller register the new cell capacity and confirms the cell accepts load before your next scheduled compliance inspection.

Charge indicator staying red after fitting the OSA004 replacement

Ni-MH cells lose voltage during storage. If the cell voltage sits outside the float acceptance window when first installed, the charge controller holds a fault state and the indicator stays red. This is not a wiring fault. Leave the fitting on mains power for a full 24-hour charge cycle — most OSI controllers will transition to green once the cell reaches approximately 5.4–5.6V at float. If the indicator stays red beyond 48 hours, check that the connector is fully seated and the cell voltage at the terminals is rising.

Emergency light dims and cuts out partway through a duration test

A new Ni-MH cell does not deliver full rated capacity on its first activation — it needs at least one complete charge-discharge cycle to condition the cell chemistry. If the light dims or cuts short during a test immediately after installation, the cell was not yet fully conditioned. Recharge for a full 24 hours before repeating the test. After one complete cycle, capacity should reach the rated 2000mAh and the fitting should hold illumination for the full test duration.