Portable Power Station Sizer

A CPAP without its heated humidifier draws about 40 W, so one night of 8 hours is 320 Wh at the mask and about 375 Wh from the battery after inverter losses. A 300 Wh unit gets most people through one night on a DC cable, a 500 to 700 Wh unit covers one night with room to spare, and a 1,000 Wh unit covers about two and a half nights. Turn the humidifier off on battery, because with it on the draw roughly triples.

About 16 hours. A full-size fridge draws around 150 W while the compressor runs, and the compressor runs about 35% of the time, so the average draw is about 52 W. 1,000 Wh x 0.85 usable divided by 52 W is roughly 16 hours. A 2,000 Wh unit runs it for about 32 hours. Keeping the door shut and the fridge full stretches this.

They are closer than the marketing suggests. All four now use LiFePO4 cells, all offer 1 kWh and 2 kWh models with 1,800 to 2,600 W inverters, and all have app control. EcoFlow and BLUETTI tend to have the fastest charging and the most solar input. Jackery units are usually the lightest at a given capacity. Anker's SOLIX line is often the cheapest per watt-hour on sale. Buy on the specs the tool shows you (capacity, output, weight, solar input), not on the brand.

A 1,500 W heater runs on any unit with an 1,800 W or larger inverter, but it empties a 1,000 Wh battery in under an hour at full tilt and a 2,000 Wh battery in under two hours. Heating is where batteries make the least sense. Use an electric blanket (about 100 W) or a propane heater designed for indoor use, and keep the power station for the fridge, lights and electronics.

Yes, if the inverter is rated for it. A 1,000 W cooking microwave draws about 1,200 W from the wall, so you need at least a 1,500 W continuous inverter. Three minutes of microwaving uses about 60 Wh, so output is the limit and capacity hardly matters. Small 300 W units cannot run a microwave at all.

For a power station, yes. LiFePO4 (lithium iron phosphate, also written LFP) cells are rated for about 3,000 to 6,000 charge cycles before they fall to 80% capacity, against roughly 500 to 1,000 for the older NMC packs. They are also more tolerant of heat and less prone to thermal runaway. They do weigh more. LiFePO4 units are 20 to 30% heavier for the same watt-hours. Nearly every current model from the big four is LiFePO4.

Almost all current models support pass-through charging, so you can run a load while the unit is plugged into the wall or a solar panel. Units that list a UPS switchover time (10 to 20 ms) will also keep a load running if the wall power drops, which is fine for a router, a fridge or a CPAP but not something to rely on for a desktop PC during a brownout. Pass-through does add heat, so expect slower charging when the load is heavy.

LiFePO4 units lose about 2 to 3% a month sitting idle, so a full unit is still around 80% after six months. Makers recommend storing at 50 to 80% charge and topping up every three to six months. Leave it plugged in only if the unit has a storage mode that holds the charge below 100%. Sitting at 100% for months is harder on the cells than sitting at 60%.

Usually. A typical camping load of a cooler fridge, lights, phones and a laptop is about 600 to 900 Wh a day, so a 2,000 Wh unit covers two days without recharging and three with a 100 to 200 W panel. It is not enough if you plan to run an electric kettle, induction cooktop or a space heater regularly, since each of those uses several hundred watt-hours an hour.

Surge (or peak) watts is the output the inverter can supply for a second or two while a motor starts. A fridge compressor rated at 150 W running can draw 1,000 to 1,200 W for a moment at start-up, and a sump pump or window AC pulls two to three times its running watts. The station's surge rating has to cover the largest start-up plus whatever else is already running, which is what the tool checks.