DSC WTK5504 Wireless Keypad Replacement Battery 4.8V 2000mAh

DSC WTK5504 Wireless Keypad — 4.8V Ni-MH Replacement Battery (4PH-H-AA2100-S-D22)

This 4.8V 2000mAh Ni-MH battery replaces the internal pack in the DSC WTK5504 wireless keypad and the WS4920HE wireless repeater. Both devices run on the same four-cell Ni-MH pack at 4.8V nominal, sharing the same connector and BMS handshake with the DSC alarm panel. Capacity is 2000mAh (9.6Wh), matching the original specification.

• WTK5504 and WS4920HE compatibility: Both devices draw from the same 4.8V rail and use identical connector housings and cell counts. The DSC panel communicates with these devices over a shared RF link that checks supply voltage — a mismatched pack voltage trips a low-battery flag at the panel even when the physical connection is solid.
• Bench tested on actual hardware: We cycled this pack through charge and discharge on a DSC-compatible test rig. The BMS accepted the cell chemistry without fault codes, and the pack held voltage within the panel's acceptance window across a full conditioning cycle.
• Float charge before first zone test: Do not run a diagnostic zone test immediately after swapping this pack. Allow 24 to 48 hours on float charge first. The panel samples battery voltage during a test, and an under-conditioned Ni-MH cell will read low even when physically healthy, triggering a false low-battery fault on the control panel.

Why the WTK5504 reports low battery hours after a fresh pack is installed

Ni-MH cells leave storage at partial charge — typically 40 to 60% of rated capacity. The DSC panel polls the keypad's supply voltage on a fixed schedule, and a partially charged pack sits below the panel's acceptance threshold of approximately 4.6V under load. The panel logs a low-battery event even though the new cell is functioning correctly. Running the pack on float charge for 24 to 48 hours brings cell voltage up to the 4.8V nominal level the panel expects.

Alarm panel losing saved zones after a mains outage with a recently replaced battery

The WTK5504 relies on its internal pack to retain programming when mains power drops. A freshly installed Ni-MH cell that has not completed a full conditioning cycle cannot sustain the standby current draw long enough to keep SRAM-backed memory alive during an extended outage. This is a charge-state issue, not a cell fault. Condition the new pack for 48 hours on the panel before the next planned mains interruption — at full float the pack should hold above 4.5V under the panel's standby load.