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    "slug": "battery-runtime-hours",
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        "rendered": "How Many Hours Will a 5, 10, or 16 kWh Battery Run Your Home? A Calculation Guide"
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        "rendered": "<div class=\"vgblk-rw-wrapper limit-wrapper\">\n<p class=\"wp-block-paragraph\">A home battery&#8217;s runtime is <code>(nameplate kWh \u00d7 allowed depth of discharge \u00d7 inverter efficiency) \u00f7 your actual load in kW<\/code>, so no battery has one guaranteed number of backup hours. This guide uses conditional examples for 5, 10, and 16 kWh systems, including a 16 kWh example, and shows the five factors that change the result. It is the reverse companion to our guide on <a href=\"\/en\/blog\/how-to-choose-lifepo4-battery\/\">how to choose the right size of battery<\/a>: that one turns your needs into a capacity, this one turns a capacity into hours.<\/p>\n\n\n\n<section id=\"inverter-self-consumption\">\n<h2>Runtime assumptions and inverter self-consumption<\/h2>\n<p>The 85% factor used in the examples and FAQs below is an illustrative assumption, not a universal LiFePO4 specification. For example, 90% usable depth of discharge multiplied by 94.4% discharge efficiency is approximately 85%. Actual usable energy depends on the permitted state-of-charge window, temperature, battery condition and operating load.<\/p>\n<p>For battery-only operation with no charging input, choose one calculation boundary and keep it consistent.<\/p>\n<ul>\n<li>Battery-side measurement: runtime = available battery energy in Wh \/ average total battery draw in W. If that draw includes the inverter and all connected loads, do not apply another inverter-efficiency factor or add inverter self-consumption again.<\/li>\n<li>AC-load estimate: use discharge efficiency for the intended load and operating mode. A maximum-efficiency figure does not establish efficiency at a small backup load. Add a separate self-consumption allowance only if it is excluded from the efficiency figure you use.<\/li>\n<\/ul>\n<p>Illustrative battery-side example: 4,500 Wh available \/ 150 W total average draw = 30 hours. At 200 W total average draw, the same available energy gives 22.5 hours. These are arithmetic examples, not measured performance of a Genixgreen product.<\/p>\n<p>Record the inverter model, operating mode, average load and the source of each input. Zero-load, standby and energy-saving modes may have different specifications; use the documented mode that matches the intended backup operation.<\/p>\n<p><a href=\"\/en\/blog\/inverters-hybrid\/#inverter-comparison-checklist\">Compare inverter specifications for your backup loads<\/a><\/p>\n<\/section>\n\n\n\n<h2 class=\"wp-block-heading\">The short answer<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Runtime is usable energy divided by average load, with both measured at the same system boundary. For an AC-load estimate, account for the permitted battery discharge window and battery-to-AC losses at that load. The 85% factor in this guide is an example assumption, not a fixed property of LiFePO4. A runtime figure is meaningful only alongside its load and operating assumptions.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">The runtime formula<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Here is the whole calculation in one line. The specification terms in it (usable capacity, depth of discharge, round-trip efficiency) are defined in full in our <a href=\"\/en\/blog\/batteries-lifepo4\/\">complete LiFePO4 buyer&#8217;s guide<\/a>; here we only use them, and link back rather than repeat them.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Runtime (hours) = (nameplate kWh \u00d7 depth of discharge \u00d7 inverter efficiency) \u00f7 your load in kW<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">Start with usable energy, not the nameplate kWh<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Check whether the battery specification states nominal or usable energy. If it states nominal energy, apply the permitted discharge window from the model documentation and system settings. If it already states usable energy for that window, do not deduct the reserve again. For an AC-load estimate, use one-way battery-to-AC efficiency at the intended load, not charge-plus-discharge round-trip efficiency. For illustration only, 10 kWh nominal energy multiplied by 90% usable depth of discharge and 94.4% discharge efficiency gives about 8.5 kWh delivered to AC loads.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Then divide by your real load in kilowatts<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Your load is the other half of the formula, and it decides everything. Capacity is measured in kilowatt-hours (kWh), the size of the tank; load in kilowatts (kW), the rate you draw from it. Divide one by the other and the same stored energy gives many hours at a low draw and few at a high one.<\/p>\n\n\n\n<h4 class=\"wp-block-heading\">So how many hours, really?<\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">For the illustrative table below, multiply nameplate kWh by 0.85 and divide by the assumed average AC load in kW. Use this shortcut only under the assumptions stated above. It is an estimate, not a guaranteed runtime or a universal upper bound. Actual results may be higher or lower when the inputs change.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Worked examples: the same battery, very different hours<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The table below runs the formula for three common sizes at two loads: an &#8220;essentials only&#8221; load of about 0.25 kW (fridge, LED lighting, router and ONT, phone and laptop) and a heavier load of about 0.8 kW (the same essentials plus a gas-boiler circulation pump and more devices). Read every figure as &#8220;at this assumed load,&#8221; never as a fixed property of the battery.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Battery (nameplate)<\/th><th>Delivered energy (85% example)<\/th><th>At ~0.25 kW (essentials only)<\/th><th>At ~0.8 kW (essentials plus heating)<\/th><\/tr><\/thead><tbody><tr><td>5 kWh<\/td><td>~4.25 kWh<\/td><td>~17 hours<\/td><td>~5 hours<\/td><\/tr><tr><td>10 kWh<\/td><td>~8.5 kWh<\/td><td>~34 hours<\/td><td>~11 hours<\/td><\/tr><tr><td>16 kWh<\/td><td>~13.6 kWh<\/td><td>~54 hours<\/td><td>~17 hours<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">Why the same battery shows two different numbers<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Look across a single row. The 5 kWh battery runs roughly 17 hours at a light load and roughly 5 at a heavier one, a threefold difference from one product, decided entirely by what you plug into it. Runtime is a property of the battery and the load together, never of the battery alone, so a runtime figure with no load attached cannot be checked. The useful version is always conditional: this battery runs about this long at about this load.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Estimate your own load in five minutes<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The table above uses assumed loads. To make it yours, you only need a rough figure for what runs at the same time during an outage. The full method for building a critical-load list, with the two-column must-run exercise, lives in our <a href=\"\/en\/blog\/how-to-choose-lifepo4-battery\/\">guide on how to choose the right size<\/a>; here is the compact version that feeds the runtime formula.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">A quick appliance-wattage method<\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Appliance<\/th><th>Typical wattage<\/th><th>Notes<\/th><\/tr><\/thead><tbody><tr><td>Refrigerator<\/td><td>100 to 200 W<\/td><td>cycles on and off, so average draw is lower. See the <a href=\"\/en\/blog\/fridge-backup-power\/\">fridge backup-power guide<\/a> for appliance-specific planning.<\/td><\/tr><tr><td>LED lighting, several rooms<\/td><td>around 50 W<\/td><td><\/td><\/tr><tr><td>Router and ONT<\/td><td>20 to 40 W<\/td><td>runs continuously<\/td><\/tr><tr><td>Gas-boiler circulation pump<\/td><td>50 to 100 W<\/td><td>critical for heating<\/td><\/tr><tr><td>Laptop and phone charging<\/td><td>around 100 W<\/td><td><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\">Plug your load into the formula<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Estimate the average combined load during the outage, allowing for appliances that cycle on and off, then divide watts by 1,000 to get kilowatts. Under the illustrative 85% delivered-energy assumption, a 10 kWh battery provides about 8.5 kWh to AC loads. Dividing by an assumed 0.3 kW average AC load gives about 28 hours. Replace both assumptions with data for your system and appliance use.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Five things that make real runtime differ from the headline<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The formula gives an estimate for the inputs you choose. The following factors can change those inputs; do not deduct a loss twice if it is already included in usable energy or measured battery draw.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Usable capacity and depth of discharge<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">You never get the nameplate kWh. Usable energy is the nameplate multiplied by the depth of discharge, so the first and largest gap between the headline and reality is built into the battery itself, as <a href=\"https:\/\/batteryuniversity.com\/article\/bu-808-how-to-prolong-lithium-based-batteries\" target=\"_blank\" rel=\"noreferrer noopener\">Battery University (BU-808)<\/a> explains. Size your expectations from usable energy, not from the number on the box.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Inverter conversion and standby losses<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Turning stored direct current into household alternating current is not free, and the inverter also draws a small amount continuously just to stay awake. Both shorten real runtime versus a paper calculation, and a very light load does not stretch as far as simple division suggests, because the inverter&#8217;s standby draw becomes a larger share of a small load.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Cold temperature in a Ukrainian winter<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Temperature changes how much energy a battery can actually deliver. As the cells get colder their available discharge capacity falls, so a battery in an unheated space gives fewer usable kWh, and therefore fewer hours, on a freezing night than the same battery in a warm room, as <a href=\"https:\/\/batteryuniversity.com\/article\/bu-410-charging-at-high-and-low-temperatures\" target=\"_blank\" rel=\"noreferrer noopener\">Battery University (BU-410)<\/a> explains. Discharge itself is allowed in the cold: most LiFePO4 batteries discharge down to around minus 20 \u00b0C with reduced capacity, so the battery keeps your home running. The hard limit is on charging, which must not happen below 0 \u00b0C unless the battery has a self-heating circuit that warms the cells first. For runtime, the rule is simple: keep the battery in a heated indoor space and you keep its full hours; leave it in the cold and you lose some.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Battery age and cycle degradation<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A battery delivers fewer hours late in its life than when it was new. With each charge and discharge cycle, usable capacity slowly fades toward the 80 percent end-of-life point that the industry uses to define a battery&#8217;s rated lifespan, as <a href=\"https:\/\/batteryuniversity.com\/article\/bu-808-how-to-prolong-lithium-based-batteries\" target=\"_blank\" rel=\"noreferrer noopener\">Battery University (BU-808)<\/a> sets out, so an older unit gives noticeably fewer hours at the same load than a new one, while still working past that point and simply storing less. LiFePO4 is the slowest mainstream chemistry to fade, which is part of why it is the standard for daily-cycled home storage, as <a href=\"https:\/\/batteryuniversity.com\/article\/bu-205-types-of-lithium-ion\" target=\"_blank\" rel=\"noreferrer noopener\">Battery University (BU-205)<\/a> notes, but plan for the number to drift down over the years.<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Surge and startup loads<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Motors draw a brief surge several times their running watts at the instant they start: a refrigerator compressor or a pump can spike well above its steady figure for a second or two. It barely touches runtime, but it decides whether the system holds up at all. The surge sizes the inverter&#8217;s peak rating, not the runtime; an undersized inverter trips on the surge and cuts the power long before the battery is empty, which feels like terrible runtime but is really an inverter mismatch. Use the <a href=\"\/en\/blog\/inverter-sizing-formula\/\">inverter sizing formula<\/a> to check the peak-load side, and route any hardwired work to a qualified electrician.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">How to get more hours<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If the estimate is shorter than you need, there are two honest levers. Pair the battery with solar so it recharges during daylight instead of waiting for the grid, which multiplies the hours it covers across a long outage; and reduce the load by dropping non-essential appliances. If runtime is still structurally short, the real fix is capacity, not a runtime trick, and that is a sizing question our <a href=\"\/en\/blog\/how-to-choose-lifepo4-battery\/\">guide on choosing the right size<\/a> and the <a href=\"\/en\/blog\/batteries-lifepo4\/\">pillar buyer&#8217;s guide<\/a> walk in full.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Frequently asked questions<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>How many hours will a 10 kWh battery run my house?<\/strong><br>There is no single runtime. Using the illustrative 85% delivered-energy assumption gives 8.5 kWh from a 10 kWh nominal battery: about 34 hours at 0.25 kW average AC load, or 11 hours at 0.8 kW. These are conditional estimates, not product guarantees. Use the available energy and average load for your system.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>How do I calculate battery runtime?<\/strong><br>With no charging input, divide available energy by average power at the same system boundary. At the battery side, use available battery Wh divided by total battery draw in W. For an AC-load estimate, account for the permitted discharge window and battery-to-AC efficiency at that load. Do not deduct reserve, conversion losses or inverter self-consumption twice.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Why does my battery not deliver its full kWh rating?<\/strong><br>The label may state nominal energy rather than energy available within the permitted state-of-charge window. Battery condition and temperature can change available energy, while conversion losses affect energy delivered to AC appliances. Check the model documentation and actual operating conditions. There is no universal 85% delivered-energy factor for all LiFePO4 systems.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Does cold weather reduce how long my battery lasts?<\/strong><br>Yes. As the cells get colder their available discharge capacity falls, so a battery in an unheated space delivers fewer hours on a freezing night than the same battery in a warm room. Discharge still works down to around minus 20 \u00b0C with reduced capacity. Charging is the restricted action: a standard LiFePO4 battery must not be charged below 0 \u00b0C without a self-heating circuit. Keeping the battery in a heated indoor space preserves its full runtime.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Does a battery run for fewer hours as it gets older?<\/strong><br>Yes, gradually. Usable capacity fades with each cycle toward the 80 percent end-of-life point used to rate battery lifespan, so an older unit delivers fewer hours at the same load than a new one. It keeps working past that point, simply storing less. LiFePO4 fades more slowly than other mainstream chemistries, so the drift is gentle, but plan for the runtime number to ease down over the years.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>How can I make my battery last longer during an outage?<\/strong><br>Two levers work. Pair the battery with solar so it refills during daylight rather than waiting for the grid, and switch off non-essential appliances. If runtime is still too short, the answer is more capacity, a sizing decision covered in our guide on choosing the right size.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">The right next step<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Calculate runtime from usable energy and average load at the same system boundary, using documented or measured inputs. Treat the 85% factor here as an illustration. If the resulting estimate is shorter than your outages, review both essential loads and system sizing. Start with our <a href=\"\/en\/blog\/how-to-choose-lifepo4-battery\/\">guide on how to choose the right size of battery<\/a>, and for the full specification definitions behind the formula, see our <a href=\"\/en\/blog\/batteries-lifepo4\/\">complete LiFePO4 buyer&#8217;s guide<\/a>. If you are weighing chemistries, see how LiFePO4 compares with <a href=\"\/en\/blog\/lifepo4-vs-lead-acid-backup-power\/\">lead-acid for backup power<\/a>. To see the range, including the systems we hold in our Odesa-region warehouse for fast local supply, visit our <a href=\"\/en\/product\/\">product range<\/a>. If you are a dealer or installer serving customers in Ukraine, our <a href=\"\/en\/partners\/\">partners page<\/a> explains how to work with us.<\/p>\n<\/div><!-- .vgblk-rw-wrapper -->",
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        "rendered": "<p>Estimate battery backup hours from usable energy and actual load, with 5, 10 and 16 kWh examples and the factors that change runtime.<\/p>",
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