The formula
Run time (h) = Capacity (Wh) × Output efficiency ÷ Load (W)
Recharge time (h) ≈ Capacity (Wh) ÷ (Charging watts × 0.9)
Worked example
A 1,000 Wh power station running a 100 W device from the AC socket: 1,000 × 0.85 ÷ 100 = 8.5 hours. From the 12 V or USB outputs, which skip the inverter, the same device would run about 9 hours.
Tips
- Switch the AC inverter off when you don't need it; it draws power even with nothing plugged in.
- Solar input is rarely the panel's full rating. A 200 W panel might average 120–150 W in good sun.
- Cold weather reduces capacity and most units won't charge below freezing.
Frequently asked questions
How long will a 1000Wh power station run a fridge?
A compressor fridge averaging 40–50 W would run for roughly 17–21 hours from the AC socket, or longer on 12 V.
How long will a 500Wh power station run a CPAP?
A CPAP using 30–60 W without a humidifier would run about 7–14 hours from the DC output. With heated humidification, much less.