About this replacement
DSC 3G4000 / LE4000 Series — 7.2V Ni-MH Replacement Battery (3G4000-BATT)
This is a 7.2V 2000mAh Ni-MH rechargeable battery for the DSC 3G4000 and LE4000 alarm control panels, including 3G4000 Cellular Communicators. It replaces OEM part 3G4000-BATT and restores backup power to the panel during mains outages. Capacity is 2000mAh (14.4Wh), matching the original specification.
- 3G4000 and LE4000 panel fit: Both panels run the same 7.2V battery rail with identical connector pinout and BMS handshake protocol. A single cell covers both units — no adapter or wiring change needed.
- Bench tested on actual hardware: We cycled this cell on a 3G4000 panel under mains-cut conditions. The BMS accepted charge without fault codes and held voltage above the panel's low-battery threshold through a full discharge cycle.
- Float charge conditioning after install: Do not run a zone test immediately after fitting this cell. Allow 24–48 hours on float charge first. Installing a fresh Ni-MH cell and testing too soon will trigger a false low-battery report — the panel needs time to recognise the new cell as fully charged.
Alarm panel showing low battery hours after installing new cell
This is a known behaviour with Ni-MH cells on DSC panels, not a faulty battery. The panel's charge monitor reads voltage during the first float cycle and reports low until the cell reaches a stable charge state. A fresh cell sitting at the mid-point of its first charge will read below the panel's acceptance threshold. Leave the panel powered on mains for 48 hours — the low-battery alert will clear once the cell crosses approximately 8.4V fully charged.
Alarm losing programming during a mains outage after battery swap
If the panel drops its configuration during a power cut shortly after a battery replacement, the new cell has not yet completed its conditioning cycle. The panel backup circuit requires the cell to hold a minimum voltage under load — a partially charged Ni-MH cell collapses under draw faster than the panel expects. The fix is straightforward: restore mains power, allow a full 48-hour charge cycle, then test with a deliberate mains-cut. Check the panel's battery voltage reading in the engineer menu — it should show above 7.0V under load before relying on backup.