Size Your Battery Backup
Adjust your backup load and hours the recommended capacity updates live.
How battery sizing works
Multiply your backup load (watts running together) by the hours you need, then divide by the usable depth of discharge about 90% for lithium (LiFePO4), only ~50% for tubular. Size to your essential circuits fans, lights, fridge, Wi-Fi and maybe one inverter AC not the whole house. Oversizing wastes capital; undersizing trips the BMS mid-outage.
Battery Sizing Calculator FAQs
An inverter AC averages ~1.2kW, so roughly 5kWh of usable lithium per 3-4 hours of AC runtime, on top of your other essentials.
Lithium gives 80-90% usable capacity and thousands of cycles; tubular only ~50% and far fewer cycles. Per usable unit over ten years, lithium is cheaper.
Only for backup during load-shedding. A pure on-grid system saves money without one; add storage if outages disrupt your home.
Yes place it in a shaded, ventilated indoor spot. Sustained heat above 25°C shortens any battery’s life.
Get a hybrid sized to your outages.
A free survey sizes the battery to your essential loads and outage pattern no over- or under-spend.