Visonic PowerMaster 360 Replacement Battery 3.7V 900mAh

Visonic PowerMaster 360 Series — 3.7V Li-Polymer Replacement Battery (103-305328)

This 3.7V, 900mAh lithium-polymer battery replaces part number 103-305328 in the Visonic PowerMaster 360 and PowerMaster 360-pg2 security control panels. These panels run on a single flat Li-Polymer cell to maintain wireless communication, alarm logic, and zone monitoring. When the original cell degrades, the panel loses the ability to sustain operations during mains power interruptions.

• PowerMaster 360 and 360-pg2 compatibility: Both panel variants share the same battery bay dimensions, connector pinout, and BMS handshake protocol — 64.90 × 45.00 × 3.10mm with a matched 3.7V nominal voltage rail. Swapping between variants requires no modification.
• Bench tested on actual hardware: We ran this cell through charge and discharge cycles on the PowerMaster 360 platform. The BMS accepted the cell without fault codes, and the panel held its zone configuration throughout the power transition.
• Post-swap network re-join timing: After installing this battery, wait a full 60 seconds before expecting the panel to fully resume communication. The PowerMaster 360 runs a mesh network re-join sequence after any power interruption — cutting that window short can cause a false offline status on your monitoring app.

Why the PowerMaster 360 drains its battery faster after a network change

If the panel polls more frequently — triggered by a hub firmware update, a network topology change, or a new device added to the mesh — current draw from the battery increases. The 103-305328 cell is sized for standard polling intervals. A congested or high-traffic network can cut cell life significantly without any fault showing on the panel itself. Check your hub's polling interval settings and reduce them if the panel is checking in more than once every few minutes.

Low battery alert showing immediately after fitting a new cell

A fresh Li-Polymer cell that has been in storage may sit below 3.5V — enough to trigger the PowerMaster 360's low-voltage alert threshold before the panel has had time to charge it. This is a storage voltage issue, not a faulty cell. Leave the panel connected to mains power for at least two hours after installation. The alert should clear once the cell charges above the panel's 3.6V alert cutoff.