About the Battery Backup Calculator
When the grid goes down, runtime is what matters.
This tool estimates how long your battery can keep essentials running.
How this calculator works
We divide usable battery capacity by your essential load to estimate backup hours.
Why it matters
- Plan for outages confidently
- Prioritise essential circuits
- Right-size backup capacity
- Avoid nasty surprises
Frequently asked questions
It depends on capacity and load — a 13.5 kWh battery may run essentials for a day or more.
Yes, if paired with solar the battery can recharge each day.