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How long will your Felicity Solar battery last?
Enter your system and your average consumption: the calculator gives the usable energy, the hours of autonomy and the time the batteries reach your cut-off.
A Felicity 48 V 100 Ah battery holds about 5.12 kWh, a 200 Ah model about twice that. For a home that relies on the battery during outages, a 20 % reserve is a sensible cut-off: it leaves something for the next cut.
Felicity Monitor does this calculation live, with your real consumption: the dashboard shows when the batteries will be full or reach your cut-off. See it in the demo →
The formula
autonomy = capacity × health × (charge − cut-off) × efficiency ÷ (consumption + inverter’s own consumption)
Example with two Felicity 48 V 100 Ah batteries: 10.24 kWh, from 90 % to a 20 % reserve, behind an inverter at 92 % that uses 40 W for itself, with the house drawing 450 W on average: 10.24 × 0.7 × 0.92 ÷ 0.49 ≈ 13.5 hours.
Why real runtime is often shorter
- One weak cell ends the discharge. The BMS stops the battery when its lowest cell reaches its limit, even if the others still hold energy. A growing cell spread shortens the night.
- The displayed charge drifts. The state of charge is counted, not measured: without a full charge from time to time, it can be several points off.
- Cold reduces what you can take out. Below about 10 °C a lithium battery delivers less, and many BMS limit the current.
- Peaks cost more than the average. A kettle or a pump at 2 kW for a few minutes weighs more than its share, because of losses and current limits.
Typical night consumption in a home is 100 to 250 W; in the evening, 400 to 1,000 W. Your own figure is on the dashboard of your box after a few days.
Keep reading
A clear view of your Felicity battery
Pre-order now. The box is tested on Felicity batteries before it ships on 10 November 2026.