In short
- What matters is the charge at the start of each cut, not the average over the day.
- Know what the house draws during a cut, and keep heavy loads for when the grid is back.
- An alert one hour before a cut, if the battery is low, gives you time to react.
With a timetable you know when the power will go. That is an advantage: you can plan. The usual trouble is not the battery size but its charge at the wrong moment, for example a cut at seven in the evening after a cloudy afternoon.
Know your cut load
During a cut, only the circuits on the inverter’s backup output run. Look at one cut with Felicity Monitor and note the average power: lights, fridge, internet, a fan. Multiply by the length of the cut and add a margin. That is the energy the battery must hold when the grid goes.
Start each cut full enough
If your inverter allows charging from the grid, schedule it to finish before the next cut, so a grey day does not leave you short. If it charges from the sun only, keep heavy loads such as the iron or the water heater for the hours when the grid is on. The battery then spends its energy where you need it.
On the day
Felicity Monitor shows the battery’s charge, power and temperature live, and the free Cloud keeps the history of every cut. After a week you know exactly how many percent a four-hour evening cut takes, which tells you far more than the label on the battery.
Two alerts
- One hour before a long cut, if the charge is under the level you need, a message so you can switch heavy loads off.
- During a cut, if the charge falls under 20 %, a second message: time to cut down to the essentials.
The box only reads the battery. Deciding what to switch off stays with you, or with Home Assistant if your loads are on smart plugs.
Common questions
Does Felicity Monitor know the cut timetable?
No. You set the alert times yourself in Home Assistant, or simply check the charge before the cut.
Does the box keep working during a cut?
Yes, if it is powered from a socket on the inverter’s backup output. Remote viewing also needs the router to be on backup.
How do I know how long the battery will last?
Look at one real cut: the percentage used per hour, at your usual load, is your real figure.
