Battery Backup Calculator
Choose the appliances you want to run during a power cut and how long you need backup. We will suggest the inverter size and the right Truenergy battery.
1Your appliances
-
watts each
2Backup needed
hrs
Your result
- Total load
- W
- Inverter size
- VA
- Batteries
- × 12V
- Capacity needed
- Ah
Each battery should be about for hours at W.
Add at least one appliance to see your result.
Recommended batteries
Your load is high for a single battery set. Our team can suggest a bigger system.
Estimates assume 80% overall efficiency. Actual backup depends on battery age, temperature, inverter efficiency and usage. Disclaimer.
How the backup calculator works
We add up the power used by the appliances you selected (the load in watts), then work out the inverter size and the battery capacity needed for your backup time:
- Inverter size (VA) ≈ load ÷ 0.8 power factor, rounded up to the next standard size with a 10% margin.
- Battery capacity (Ah) ≈ (load × backup hours) ÷ (battery voltage × 0.8 efficiency).
- Inverters above 1100 VA usually run on 2 batteries (24V); bigger systems use 4.
Need help with a larger home, shop or office? Talk to our team.