Use this free calculator to plan running and starting load for backup appliances. Change the load, starting surge, losses and battery limits to match your equipment.
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Every input includes a simple explanation.
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Motors and compressors can need extra power when they start.
Battery age, temperature and a high discharge rate can reduce delivered energy.
Use this as a planning range. Confirm continuous rating, peak rating and battery compatibility with the manufacturer and a qualified installer.
Running watts describe steady demand while peak watts and power factor shape the minimum planning VA for backup equipment.
List only appliances intended for backup and obtain starting-current information for motors, compressors and pumps.
Adding all nameplate watts without distinguishing simultaneous use and starting surge can size the system in the wrong direction.
Planning VA = max(running watts, peak watts) ÷ power factor × safety margin
List only appliances intended for backup and obtain starting-current information for motors, compressors and pumps.
Adding all nameplate watts without distinguishing simultaneous use and starting surge can size the system in the wrong direction.
Use this as a planning range. Confirm continuous rating, peak rating and battery compatibility with the manufacturer and a qualified installer.