Honeywell 300-11186 Home Pro A7 Replacement Battery 3.7V 10000mAh

Honeywell Home Pro A7 Series — 3.7V Li-ion Replacement Battery (300-11186)

This 3.7V, 10,000mAh lithium-ion cell replaces the backup battery in the Honeywell Home Pro A7, Pro A7 Plus, Pro A7 Plus C, and Resideo PROA7C alarm control panels. When mains power drops, this battery keeps alarm monitoring and cellular communication active. OEM part number 300-11186 confirms direct fitment across all four panel variants.

• Pro A7 panel family compatibility: The Pro A7, Pro A7 Plus, Pro A7 Plus C, and PROA7C all share the same battery bay dimensions, connector pinout, and BMS handshake protocol — one cell covers every variant in the series without modification.
• Bench tested on actual hardware: We cycled this cell through simulated mains-loss events on a Pro A7 Plus panel. The BMS accepted the new cell within the expected initialisation window, and the panel held zone programming and communicator status throughout discharge and recovery.
• Post-install float charge window: Do not run a zone diagnostic or test the siren immediately after swapping this cell. Allow 24 to 48 hours on float charge first — the panel's BMS needs that window to fully accept the new cell before it will report accurate charge status.

Alarm panel showing low battery hours after installing new cell

This is a BMS initialisation issue, not a fault with the cell. The Pro A7 panel measures battery state by monitoring float charge acceptance over time — a freshly installed cell has not yet gone through that process. The panel will continue to flag low battery until the cell reaches full float, which typically takes 24 to 48 hours on mains power. Once the BMS clears the condition, the low battery alert will drop without any manual reset.

Panel loses zone programming during a power outage after battery replacement

If the new cell has not completed its 48-hour conditioning period, the panel may not draw enough backup current to hold volatile memory during a mains failure. The control board needs a stable, accepted battery — not just a connected one — to sustain programming during outages. Restore mains power, allow the full conditioning window to complete, then confirm the panel shows a healthy battery status before the next outage. After that, programming retention across power cuts should be normal.