Honeywell PROA7BAT2 Alarm System Compatible Battery 3.7V 6700mAh

Honeywell Home PROA7 Series — 3.7V Li-ion Replacement Battery (PROA7BAT2)

This is a 3.7V, 6700mAh lithium-ion battery for the Honeywell Home PROA7 alarm system control panel. It fits the PROA7, PROA7PLUS, Resideo PROA7C, and Resideo PROA7PLUSC panels. It provides backup power to the panel when mains power is interrupted, keeping the alarm system live during an outage.

• PROA7 and PROA7PLUS platform fit: The PROA7, PROA7C, PROA7PLUS, and PROA7PLUSC share the same battery bay, connector pinout, and BMS handshake protocol. One cell fits all four variants without modification.
• Bench tested on actual hardware: We ran this cell on a PROA7 panel under simulated mains-loss conditions. The BMS accepted the cell without fault codes, held float charge correctly, and the panel reported battery status as normal after the 48-hour conditioning window.
• Float charge conditioning on the PROA7: After fitting this cell, leave the panel on mains power for 48 hours before running any zone or siren test. The PROA7 charges the backup cell at a low float rate — running diagnostics before the cell reaches full charge will trigger a false low-battery alert on the panel keypad.

Alarm panel showing low battery hours after installing new cell

The PROA7 does not fast-charge its backup battery. It trickle-charges at a controlled float rate, so a freshly installed cell will sit below the panel's acceptance threshold for up to 48 hours. During that window, the panel reads the cell voltage as insufficient and throws a low-battery fault — even when the new cell is healthy. This is a panel behaviour, not a cell fault. Leave the panel connected to mains for a full 48 hours and the fault will clear once the cell reaches the required float voltage of approximately 4.1V.

Alarm losing programming during a power outage after battery swap

If the panel drops its zone programming or user codes during a mains outage shortly after a battery replacement, the new cell had not yet been accepted by the BMS. The PROA7 will not draw load from the backup cell until it has completed its conditioning cycle — if mains fails mid-cycle, the panel loses its power source and resets to factory defaults. The fix is to allow the full 48-hour float charge on mains before the panel is considered protected. After conditioning, trigger a deliberate mains-loss test to confirm the panel holds programming and maintains communication on battery alone.