Easy Rapid Calcs - Easy Rapid Calcs

⚡ Power Station Runtime Calculator Pro Runtime, days of backup, solar recharge, surge check and the right station size, in one place. 🖨️ PDF Report ⬇️ CSV 📋 Copy 💾 Save 📂 Load ↺ Reset 1Your power station Watt-hours (Wh) Amp-hours × Volts Capacity (Wh)On the label or spec sheet. Capacity (Ah) Battery voltage (V)12.8 V for most LiFePO4 packs. Rated AC output (W) Surge / peak (W) Battery chemistryLiFePO4 (LFP)NMC lithium-ion Battery health (%)100 for new; lower for older units. Main output usedAC outlets (inverter)DC / USB / 12V only Conversion efficiency (%) Inverter idle draw (W)Power the inverter uses just being on. TemperatureWarm, above 68°F / 20°CMild, 50–68°F / 10–20°CCool, 32–50°F / 0–10°CFreezing, below 32°F / 0°C Reserve to keep (%)Charge you don't want to use. 2DevicesUntick a device to exclude it Add a device Qty + Add OnDeviceWattsQtyHrs/daySurge WDaily Wh Running load: –Peak with surge: –Daily use: – 3Recharging & planning Solar panels (W)0 if no solar. Peak sun hours / dayAbout 3–6 in most of the US. Solar real-world yield (%) Wall charging input (W) Backup target (days)Used for the size recommendation. Continuous runtime – All ticked devices running at once Days of backup–Using your hours/day plan With solar–Solar adds 0 Wh/day Usable energy–After health, temp & reserve Daily energy–From battery incl. losses Wall recharge–Empty to full Solar recharge–Empty to full, no load ⚙Output check Running load vs rated output– Peak start-up vs surge rating– Recommended station – – 📊Where your energy goesDaily Wh from battery 🔋Compare station sizesSame devices & settings SizeContinuousDaysBackup Estimates only. Real runtime varies with device behavior, battery condition and conditions. Fridge and freezer presets use average draw over a day, not running watts. Your inputs are saved in this browser. ⚡ Free Calculator + Guide Portable Power Station Runtime Calculator: How Long Will It Really Last? Enter your station's watt-hours and the devices you plan to run. Get a realistic runtime in seconds, then learn the formula, the hidden losses, and how to stretch every last watt. Quick Answer To estimate how long a portable power station will run, multiply its capacity in watt-hours (Wh) by about 0.85 to account for inverter losses, then divide by the total watts your devices draw: Runtime (hours) = Capacity (Wh) × 0.85 ÷ Load (W) Example: a 1,000 Wh station running a 100 W TV lasts about 1,000 × 0.85 ÷ 100 = 8.5 hours. 85–90%Typical AC inverter efficiency ~14 h1,000 Wh running a 60 W (average) fridge ~21 h1,000 Wh running a 40 W CPAP ~34 min1,000 Wh running a 1,500 W space heater Portable Power Station Runtime Calculator Add each device you want to power, adjust quantities, and the calculator updates instantly. Use the wattage on your device's label or charger; for appliances that cycle on and off (fridges, freezers), use the average draw, which the presets already do. 1. Your power station Battery capacity (Wh) Printed on the unit or spec sheet, e.g. 512, 1024, 2048 Wh. Output type / efficiency AC outlets (85%) AC, high-efficiency unit (90%) DC / USB / 12V only (92%) AC in cold weather (80%) Converting battery DC to AC wastes some energy as heat. Reserve to keep (%) Leave 10–20% if you want a buffer for emergencies. Rated AC output (W), optional We'll warn you if your load exceeds it. 2. Your devices Choose a device Watts Qty + Add DeviceWattsQtyTotal 3. Your estimated runtime Estimated runtime– Total load– Usable energy– Per day (24 h)– How Power Station Runtime Is Calculated Every runtime calculator, including the one above, rests on one simple idea: a battery stores a fixed amount of energy (watt-hours), and your devices use energy at a certain rate (watts). Divide one by the other and you get hours. The only extra step is subtracting the energy lost along the way. 🔋Step 1: Find capacity (Wh)Look for "Wh" on the label. If only amp-hours are listed, convert with Wh = Ah × Volts. A 100 Ah, 12.8 V battery stores 1,280 Wh. 🔌Step 2: Add up the wattsTotal every device you'll run at the same time. Two 10 W LED lamps plus a 65 W laptop = 85 W of load. 📉Step 3: Apply efficiencyMultiply capacity by 0.85 for AC outlets or about 0.92 for DC/USB ports. This covers inverter and conversion losses. ⏱️Step 4: DivideUsable Wh ÷ total watts = hours. 850 Wh ÷ 85 W = 10 hours of runtime. Worked example: You have a 2,048 Wh station and want to run a 60 W average fridge, a 12 W Wi-Fi router, and two 10 W LED bulbs (92 W total) on AC. Usable energy is 2,048 × 0.85 ≈ 1,741 Wh. Runtime is 1,741 ÷ 92 ≈ 18.9 hours. Runtime Chart: How Long a 1,000 Wh Power Station Runs Common Devices The 1,000 Wh class is the most popular size for home backup and camping. Here's how long one lasts on a single device using AC power at 85% efficiency (850 usable Wh). For other sizes, scale proportionally: a 500 Wh unit gives half these times, a 2,000 Wh unit gives double. DeviceTypical WattsRuntimeRelative runtime LED light bulb10 W~85 h Wi-Fi router / modem12 W~71 h Phone charging18 W~47 h (≈50+ full charges) CPAP (no humidifier)40 W~21 h (2–3 nights) Mini fridge / 12V cooler (avg)45 W~19 h Box fan50 W~17 h Full-size fridge (avg)60 W~14 h Laptop65 W~13 h Satellite internet dish75 W~11 h 55" LED TV100 W~8.5 h Desktop PC + monitor250 W~3.4 h Coffee maker1,000 W~51 min Microwave (input draw)1,200 W~42 min Space heater / kettle1,500 W~34 min Wattages are typical averages. Check your own device's label, since a microwave rated "1,000 W cooking power" usually pulls 1,400–1,500 W from the outlet. Which Size Do You Need? Runtime by Station Capacity A refrigerator is the device most people want to keep running in an outage, so it makes a good benchmark. This table assumes a modern fridge averaging 60 W over time (about 1.4 kWh per day) on AC power. Station SizeUsable Wh (85%)Fridge RuntimeCoverage 300 Wh255 Wh~4 h 500 Wh425 Wh~7 h 1,000 Wh850 Wh~14 h 2,000 Wh1,700 Wh~28 h 3,000 Wh2,550 Wh~42 h 5,000 Wh4,250 Wh~71 h (3 days) ⛺Camping & day trips250–700 Wh. Phones, lights, a fan, a CPAP for one night, a 12V cooler for part of the day. 🚐Van life & RV weekends1,000–2,000 Wh. Laptops, fridge, lights, and brief use of a kettle or induction plate. Pair with solar. 🏠Home backup2,000–5,000+ Wh. Fridge, router, lights, phones and medical devices through a 1–3 day outage, longer with solar or expansion batteries. 7 Things That Make Real Runtime Shorter Than the Math If your station dies earlier than the calculator predicted, one of these is almost always the reason. ♨️Inverter lossesTurning DC battery power into 120 V AC typically loses 10–15% as heat. That's why we use 0.85 as the default multiplier. 💤Idle (no-load) drawThe inverter itself consumes power just by being on, often 10–30 W depending on the unit. On tiny loads like a phone charger, this can halve your runtime. 🥶Cold temperaturesLithium batteries deliver noticeably less capacity near or below freezing. Keep the station indoors or insulated in winter. 📆Battery ageCapacity fades with cycles. An older NMC unit may hold well under its original rating; LiFePO4 fades far more slowly. 🔁Cycling appliancesFridges, freezers and pumps switch on and off. Using the label's peak wattage underestimates runtime; using too low an average overestimates it. 🚀Startup surgeMotors and compressors briefly pull 2–3× their running watts. It doesn't drain much energy, but it can trip a station whose surge rating is too low. 🛑Low-battery cutoffMany stations shut off a few percent before reaching true zero to protect the cells, and some apps let you set a higher discharge limit. LiFePO4 vs. NMC: Does Battery Chemistry Change Runtime? On a single charge, a 1,000 Wh LiFePO4 station and a 1,000 Wh NMC station run a device for roughly the same time. The difference shows up over years of use. 🟢 LiFePO4 (LFP) Typically rated for 3,000+ cycles to 80% capacity Holds its runtime for many years of daily use More thermally stable and safer Heavier and bulkier per Wh 🔵 NMC (Lithium-ion) Typically 500–1,000 cycles to 80% capacity Runtime shrinks faster with regular use Lighter and more compact Common in older and ultra-portable models How to Get More Runtime From Your Power Station Use DC and USB ports whenever possibleCharging phones and laptops through USB-C, or running a 12V fridge from the car port, skips the inverter and can add 5–10% more runtime. Switch the AC inverter off when you're not using itAn idle inverter quietly burns watts all night. If only USB devices are plugged in, turn AC off. Turn on ECO or energy-saving modeMost stations can auto-shut the AC output when the load drops below a threshold, which prevents slow overnight drain. Keep the fridge closed and fullA packed fridge holds cold longer and the compressor runs less often, lowering the average wattage you're paying for. Choose low-watt alternativesAn electric blanket (50–100 W) uses a fraction of a space heater's 1,500 W. LED bulbs beat any other lighting by far. Disable the CPAP heated humidifierThe humidifier can double or triple a CPAP's power draw. Running it dry (or on a low setting) can stretch one charge across several nights. Recharge with solar during the dayA rough daily solar estimate is panel watts × peak sun hours × 0.75. A 200 W panel in 5 sun hours adds about 750 Wh, nearly a full 1,000 Wh station. Store it charged, cool and topped upKeep the battery around 60–80% in storage and top it off every few months so it's full and healthy when the power actually goes out. Frequently Asked Questions How long will a 1,000 Wh power station run a refrigerator?Usually about 12–16 hours for a modern full-size fridge averaging 55–70 W. Older or larger fridges can draw more, so check the yearly kWh on the yellow EnergyGuide label: divide it by 8,760 to get average watts, then use the calculator above. Can a portable power station run a CPAP overnight?Yes. Most CPAP machines draw 30–60 W without a humidifier, so even a 500 Wh station handles one 8-hour night. Running directly from a DC adapter and turning off the humidifier will extend that to multiple nights. How do I convert mAh or Ah to watt-hours?Multiply amp-hours by the battery voltage: Wh = Ah × V. For mAh, divide by 1,000 first. A 20,000 mAh power bank at 3.7 V holds about 74 Wh. Always compare stations by Wh, not mAh, because mAh ignores voltage. Why did my power station run out faster than the calculator said?The most common causes are idle inverter draw on small loads, cold weather, an aging battery, or devices pulling more than their label suggests. Try lowering the efficiency setting to 80% for a more conservative estimate. Can a power station run a space heater?Only briefly. A 1,500 W heater drains a 1,000 Wh station in about 35 minutes, and many smaller stations can't supply 1,500 W at all. Heated blankets, heated clothing or a low-watt heater are far better options. Does using the DC or USB ports really extend runtime?Yes. DC outputs avoid the DC-to-AC conversion and the inverter's idle draw, so they typically deliver 90%+ of the battery's energy compared to roughly 85% through AC outlets. How long does it take to recharge a power station?Divide capacity by the charging input in watts, then add some margin. A 1,000 Wh unit taking 500 W of input needs roughly 2–2.5 hours. Many newer stations fast-charge from a wall outlet in about an hour; solar time depends on panel size and sun hours. Can I use my power station while it's charging?Most modern units support pass-through charging, letting you power devices while recharging. Some can also act as a basic UPS, switching over automatically when grid power drops. Check your model's manual for its switchover time if you're powering sensitive equipment. Know Your Numbers Before the Lights Go Out Run your real devices through the calculator above, add a 20% safety margin, and you'll know exactly which station size keeps your home, campsite or van running.