About this replacement
Honeywell Home Pro A7 Series — 3.7V Li-ion Replacement Battery (300-11186)
This 3.7V 7800mAh (28.86Wh) lithium-ion battery replaces the backup cell in the Honeywell Home Pro A7, Pro A7 Plus, Pro A7 Plus C, and Resideo PROA7C alarm control panels. It sits inside the panel enclosure and holds the system online during a mains power failure. Swap it when the panel logs a persistent low-battery fault or when the existing cell no longer holds charge.
- Pro A7 and Resideo PROA7C panel fit: All four compatible models share the same battery bay geometry, 3.7V rail, and JST-style connector. The panel's power management board handshakes with this cell's BMS the same way it does with the factory unit.
- Bench tested on actual hardware: We cycled this cell through the Pro A7 panel's charge circuit and confirmed the BMS accepted charge without triggering a fault code. Float charge settled correctly and the panel cleared its low-battery event log after the conditioning window.
- Post-installation charge window: Do not run a zone or siren test immediately after swapping this cell. The panel needs 24–48 hours on float charge before its firmware reports a healthy battery status. Testing before that window will likely surface a false low-battery alert on the keypad.
Alarm panel losing stored programming during a power outage after battery replacement
If the panel drops its zone configuration or user codes during a mains failure shortly after a battery swap, the new cell has not yet been accepted by the panel's backup circuit. The Pro A7 power board runs a brief acceptance handshake that typically completes within 48 hours of first connection. Until that handshake is confirmed, the panel may not draw from the backup cell when mains drops, causing the memory to lose power. Leave the panel on mains for a full 48-hour period after fitting the new battery before relying on it for outage protection.
Panel keypad still showing low battery fault 24 hours after cell swap
The Pro A7 panel samples the backup cell voltage at timed intervals and compares it against a threshold — typically around 3.5V at rest. A brand-new cell that has not completed its first float charge cycle may sit marginally below this threshold, keeping the fault active on the keypad. This is a firmware reporting delay, not a faulty battery. Leave the panel powered on mains for the full 48-hour conditioning period, then check that the cell voltage reads at or above 3.6V with a multimeter at the battery terminals before logging a fault.