About this replacement
Fullham FHSBATT3-F7L — 3.6V Ni-CD Replacement Battery (FHSBATT3-F7L)
This is a 3.6V, 8000mAh (28.8Wh) Ni-CD replacement cell for Fullham emergency lighting units using the FHSBATT3-F7L battery. It fits directly into the Fullham fitting and connects to the onboard charge controller. Capacity and voltage match the original specification exactly.
- Fullham FHSBATT3-F7L compatibility: Fullham emergency lighting fittings using the FHSBATT3-F7L cell share a common charge controller calibrated to a 3.6V Ni-CD float voltage. Swapping chemistry or voltage will cause the charge controller to either undercharge or overcharge the cell, both of which cause early failure and compliance issues.
- Bench tested on actual hardware: We ran this cell through a full charge cycle and a load discharge test matching the rated duration draw. The BMS accepted the cell without fault, and the charge controller moved from red to green within the expected conditioning window.
- Post-installation test cycle: Within 24 hours of installation, hold the test button for the full rated duration. This lets the charge controller register the new cell and confirms the cell accepts load before your next scheduled compliance inspection. Skipping this step is the most common reason a new battery still fails a duration test.
Emergency light failing its duration test after battery replacement
A fresh Ni-CD cell coming out of storage will not deliver full rated capacity on its first discharge. Ni-CD chemistry requires at least one complete charge-discharge cycle before the cell reaches rated capacity — this is a known electrochemical behaviour, not a defect. If a compliance test runs before this conditioning cycle is complete, the light will cut out early and log a fail. Run one manual full-duration test cycle immediately after installation to condition the cell before any scheduled inspection.
Charge indicator staying red after new battery installation
The charge controller on Fullham fittings uses cell voltage to determine whether to accept a new battery into float charge. A cell stored for several months will sit below the float acceptance window — typically under 3.3V — causing the controller to hold the fault state and keep the indicator red. Leave the fitting connected to mains for a full 24-hour charge cycle without triggering a test. If the indicator has not moved to green after 24 hours, measure the cell voltage directly: a healthy Ni-CD at full charge should read approximately 4.2V across a 3-cell pack.