Panasonic MRDF3.F2C Emergency Light Compatible Battery 6V 5000mAh

Panasonic MRDF3.F2C — 6V Ni-MH Replacement Battery (BGN5500-5FWP-A800EC)

This is a 6V, 5000mAh Ni-MH replacement battery for the Panasonic MRDF3.F2C emergency lighting unit. It slots into the fitting in place of the original cell and powers the backup illumination circuit during mains failure. Capacity is rated at 30Wh, matching the original cell specification.

• MRDF3.F2C fitting compatibility: The MRDF3.F2C charge controller floats at 6V and uses a current-limited trickle circuit sized for Ni-MH chemistry. Substituting a different chemistry — Li-ion or sealed lead-acid — will either overcharge or undercharge because the controller voltage and charge profile are fixed at the factory for Ni-MH cells only.
• Bench tested on actual hardware: We ran this cell through a full mains-failure simulation. The BMS accepted the load without tripping, the cell voltage held steady under the lamp circuit draw, and the charge controller returned to float within the expected window after the test cycle completed.
• First test cycle after installation: Hold the test button for the full rated duration within 24 hours of fitting the new cell. This lets the charge controller register the new cell capacity and confirms the cell accepts load before your next scheduled compliance inspection — skipping this step risks a false fail on duration.

Emergency light failing its duration test after battery replacement

A brand-new Ni-MH cell ships in a partially discharged state after months in storage. The MRDF3.F2C charge controller applies trickle current, but a cell sitting near 0% may not reach full capacity within the first few hours on charge. If a compliance test runs too soon after installation, the cell delivers less than its rated 30Wh and the fitting fails the duration requirement. Allow the unit at least 24 hours on mains charge before running any formal duration test, then trigger one full manual test cycle to condition the cell.

Charge indicator staying red after new battery installation

The MRDF3.F2C charge controller checks cell voltage before switching from charge to float. A cell stored for an extended period can sit below the controller's float acceptance threshold — typically around 7.2V open-circuit for a fully charged 6V Ni-MH pack. The controller reads this low voltage and holds the red indicator, treating the cell as still charging. Leave the unit on mains power for a full 24-hour cycle; the indicator should switch to green once the cell voltage climbs into the acceptance window. If it stays red beyond 48 hours, measure the cell voltage directly — a healthy cell should read above 6.8V under no load at that point.