DSC LIB2A6 GSM Communicator Replacement Battery 3.7V 2700mAh

DSC GS4005 / 3G4005 GSM Communicator — 3.7V Li-Polymer Replacement Battery (LIB2A6)

This 3.7V, 2700mAh Li-Polymer battery replaces the OEM LIB2A6 cell in the DSC GS4005 and 3G4005 GSM alarm communicators. These units transmit alarm signals to monitoring centres over cellular networks and rely on this battery as backup power when mains supply drops. Capacity is 2700mAh (9.99Wh), matching the original specification exactly.

• GS4005 and 3G4005 compatibility: Both models share the same LIB2A6 cell format, voltage rail, and connector pinout. The BMS in each communicator uses the same charge profile, so one cell covers both units without modification.
• Bench tested on actual hardware: We cycled this cell through the GS4005 charge circuit and confirmed the BMS accepted the cell, completed float charge, and cleared the low-battery flag within the expected window. No false fault codes were triggered after the conditioning period.
• GSM communicator installation tip: Do not run a zone or transmission test immediately after fitting this cell. The panel charge circuit needs 24 to 48 hours at float charge before the BMS reports a full-cell state. Testing before that window will produce a low-battery fault on the panel even though the cell is functional.

Why the GS4005 reports low battery for up to 48 hours after a new cell is fitted

The GS4005 charge circuit does not switch its battery-status flag the moment a new cell is connected. It reads accumulated charge over time and only clears the low-battery event log once the cell has reached float voltage — typically 4.1 to 4.2V at the cell terminals. A freshly installed Li-Polymer cell arrives at partial state of charge from storage, so the panel sees a voltage below its threshold and continues reporting low battery. This is normal behaviour and resolves on its own after the 24 to 48-hour conditioning window on mains power.

GS4005 loses all programming during a mains outage after battery replacement

If the new cell has not completed its conditioning cycle, its available capacity under load is lower than the panel expects. When mains power drops, the communicator draws current for cellular transmission and the cell voltage sags below the panel's cutoff threshold, causing a full reset and loss of stored configuration. The fix is to allow a full 48-hour float charge on mains before testing the backup function or triggering any power interruption. Once the cell is fully conditioned, confirm cell voltage reads at or above 4.1V before disconnecting mains.