Bticino 4239 Alarm Panel Compatible Battery 7.5V 5500mAh

Bticino 4239 — 7.5V Alkaline Replacement Battery (BT-4239)

This 7.5V 5500mAh alkaline cell replaces the backup battery in the Bticino 4239 alarm system control panel. It sits on a continuous float charge from the mains supply and takes over when mains power fails. OEM part numbers BT-4239 and KIS7207580.000 both cross-reference this cell.

• Bticino 4239 panel fit: The 4239 control panel uses a 7.5V alkaline pack at a fixed connector pinout. The panel's charge management circuit expects this specific voltage rail — fitting a different chemistry or voltage causes the panel to flag a persistent fault condition.
• Bench tested on actual hardware: We ran this cell through float charge entry, load simulation, and a hard mains-drop event. The panel accepted the cell without a reset cycle, and the BMS handed off cleanly to backup power with no voltage sag alarm.
• Post-installation float charge: Do not run a zone or siren test immediately after swapping this cell. The panel requires 24–48 hours on float charge before its charge-monitoring circuit reports accurate status. Testing earlier will likely trigger a false low-battery warning from the panel itself.

Why the 4239 panel reports low battery hours after a new cell is fitted

The 4239 charge controller does not read the cell's open-circuit voltage directly at install. It samples charge acceptance over time and only clears the low-battery flag once the cell has absorbed a threshold charge from the float circuit. A freshly fitted cell that has sat in storage will have some self-discharge, so the panel sees below-threshold charge acceptance on first contact. Leave the panel powered on mains for 24–48 hours and the flag will clear without any manual reset.

Alarm panel loses programming during a power outage after battery replacement

If the panel drops its zone configuration or user codes during a mains outage, the backup cell has not yet been accepted by the charge circuit. A cell that has not completed 48 hours of conditioning on float may not hold enough charge to sustain the panel's memory bus during a hard cutover. Restore mains power, allow a full 48-hour conditioning period, then simulate a mains failure by pulling the mains feed — the panel should hold all settings at 7.5V nominal backup voltage.