About this replacement
Dual-Lite PGP-HTR / PGW-HTR / PGZ-HTR — 8.4V Ni-Cd Replacement Battery (784H68)
This is an 8.4V, 2000mAh Ni-Cd replacement battery for the Dual-Lite PGP-HTR, PGW-HTR, and PGZ-HTR self-contained emergency lighting units. These fixtures activate automatically on mains failure to maintain illuminated exit routes in commercial buildings. It crosses to OEM part numbers 784H68 and D-SC 1800BT.
- PGP / PGW / PGZ-HTR platform fit: All three variants share the same 8.4V seven-cell Ni-Cd pack format, connector pinout, and charge controller float voltage. A single replacement cell covers the full platform without wiring modification.
- Bench tested on actual hardware: We ran this cell through a full charge cycle and load test on the PGP-HTR charge controller. The BMS accepted the cell within the float acceptance window and the charge indicator advanced to green without manual reset.
- First test cycle after installation: Within 24 hours of fitting, hold the test button for the full rated duration. This confirms the new cell accepts load and lets the charge controller register cell capacity before your next scheduled compliance inspection.
Emergency light failing its duration test after battery replacement
A freshly installed Ni-Cd cell often carries less than full charge after months in storage. The charge controller in the PGP-HTR applies a constant trickle current — it does not fast-condition a new cell automatically. During a duration test run too soon after installation, the cell hits the low-voltage cutoff early and the fitting shuts off before the rated period ends. Allow a minimum 24-hour charge on mains before conducting any compliance test, and confirm the charge LED has reached green before starting the clock.
Fitting still showing a fault LED after confirmed good installation
Some PGP-HTR and PGW-HTR units latch a fault condition in the charge controller logic when the old cell drops below approximately 6V on removal. Fitting the new cell does not clear that latch automatically. Disconnect mains power to the fitting for 30 seconds, then restore it — this forces the controller to re-initialise and re-read cell voltage. If the fault LED persists after a full 24-hour charge, measure the cell terminal voltage directly; a healthy, charged 8.4V Ni-Cd pack should read between 8.4V and 9.0V under no load.