Power needs worksheet

Arithmetic only — it can't certify anything.

This does not confirm medical-equipment runtime, generator suitability or wiring safety. Medical equipment needs an individual plan with your clinical team and supplier. Never connect a generator to a household socket, and only run one outdoors, away from openings.

Device	Watts (from its label)	Hours per day	Wh per day
			20
			40

Battery capacity (watt-hours)Usable share (%) — an assumption

Usable energy: 500 Wh × 80% = 400 Wh

Daily use: 60 Wh · Everything on at once: 18 W

Estimate with everything on: 400 Wh ÷ 18 W ≈ 22.2 hours

Estimate at your daily pattern: 400 ÷ 60 ≈ 6.7 days

Start-up surges, temperature, battery age and efficiency can all reduce real runtime.

Our approved backup arrangementse.g. "Supplier-approved battery for the oxygen concentrator — care team contact on fridge"

Read the full guide: Using backup power safely.