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Relays & Automation
Shelly
PA Systems

Alarm Battery Standby Calculator

Add up panel and device quiescent currents to size a backup battery for your required standby time, plus alarm load — with an ageing allowance built in.

Inputs

Standby (quiescent) loads

DevicemA eachQty

Standby & alarm

Results

Required battery capacity
Total standby current
Standby consumption
Alarm consumption
Smallest standard battery

Capacity = (standby current × standby hours + alarm current × alarm time) × ageing factor. Check your grade and monitoring type against AS/NZS 2201.1 for the standby time required on the job, confirm the panel's charger can recharge the chosen battery in the required time, and derate further for high ambient temperatures. Device standby currents here are typical — always use datasheet figures.