About this replacement
Dual-Lite DYN6I — 12.8V LiFePO4 Replacement Battery (784H70)
This is a 12.8V, 1800mAh LiFePO4 replacement battery for the Dual-Lite DYN6I emergency lighting unit. It matches OEM part number 784H70 and slots directly into the DYN6I fitting. Capacity is 1800mAh (23.04Wh) — use the product data figure, not third-party listings.
- DYN6I compatibility: The DYN6I charge controller runs a float voltage matched to 12.8V LiFePO4 chemistry. Swapping to a different chemistry — NiCd or sealed lead acid — shifts the float voltage outside the cell's acceptance range, triggering a fault condition or overcharge damage over time.
- Bench tested on actual hardware: We ran this cell through a full charge-discharge cycle on the DYN6I charge board. The BMS accepted the charge without tripping, and the cell held load voltage above the controller's low-voltage cutoff threshold throughout the discharge phase.
- First-cycle test requirement: Within 24 hours of installation, hold the DYN6I test button for the full rated duration. This allows the charge controller to register the new cell's capacity before your next scheduled compliance test — cells shipped from storage often sit below float voltage and need one full cycle to condition.
Charge indicator staying red after new battery installation
The DYN6I charge controller uses cell voltage to confirm a healthy battery is present before switching the LED from red to green. A LiFePO4 cell stored for several months can drop to 12.0V or below — outside the float acceptance window the controller expects on startup. The controller reads this as a fault rather than a low-charge condition. Leave the fitting powered for a full 24-hour charge cycle; once the cell climbs above approximately 13.2V the controller typically clears the fault and switches to green.
Emergency light dims partway through a duration test
Dimming mid-test is not a capacity defect — it is the BMS responding to a cell that has not completed a full conditioning cycle after installation. On first activation, a partially charged cell sags under load faster than a fully conditioned one, and the BMS reduces output to protect the cell. The fix is a complete 24-hour charge before running any duration test. If dimming continues after a full charge cycle, check the cell terminals are seated flush — a high-resistance contact will cause the same voltage sag symptom under load.