About this replacement
Custom Battery Packs 1/2AA6004S1P — 4.8V Ni-MH Replacement Battery
This is a 4.8V 600mAh Ni-MH replacement pack built to the same form factor as the original 1/2AA6004S1P. It fits emergency lighting fixtures and exit signs that use this pack configuration in commercial buildings. Voltage and capacity match the OEM spec exactly — 4.8V at 600mAh (2.88Wh).
- Emergency lighting compatibility: Exit signs and emergency backup fixtures in this class share a trickle-charge circuit tuned for 4.8V Ni-MH cell stacks. Swapping to a different voltage or chemistry trips the charge controller and the unit fails the next self-test cycle.
- Bench tested on actual hardware: We cycled this pack through charge and discharge on a Ni-MH compatible tester. The BMS held cutoff voltage correctly at both ends, and the pack reached rated capacity within the first two full cycles.
- First cycle after install: Emergency lighting charge circuits apply a low constant current. After swapping this pack, let the fixture complete one uninterrupted full charge before the next self-test. Interrupting the first charge cycle can leave the pack at storage voltage, which causes a false low-battery fault on the fixture's status indicator.
Pack running below 4.8V on first use after install
Replacement Ni-MH packs ship at storage voltage — typically 3.8V to 4.2V across a 4-cell stack. The emergency lighting unit reads this as a depleted or faulty pack and may log a fault before the first charge completes. This is not a defective pack. Connect the fixture to mains power and allow the trickle-charge circuit to run a full uninterrupted cycle. Voltage should stabilise at or above 4.8V once the cells are fully conditioned.
Fixture status LED stays red after pack swap
Most commercial emergency lighting units latch a fault code when they detect a pack change or a voltage drop below threshold. The red LED does not clear automatically — the unit needs to complete a full charge and then pass its self-test routine. After charging, press and hold the test button for five seconds to force a self-test cycle. If the LED clears and the fixture illuminates during the test, the pack is seated and charging correctly.