The latest articles on DEV Community by Temur Khasanov (@temur_khasanov_935b6ed893). https://dev.to/temur_khasanov_935b6ed893 https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F3953599%2F3f108591-2234-4b37-9e5d-780d824792c0.jpg https://dev.to/temur_khasanov_935b6ed893 en Temur Khasanov Wed, 27 May 2026 05:27:28 +0000 https://dev.to/temur_khasanov_935b6ed893/how-to-estimate-battery-runtime-from-wh-dod-efficiency-and-load-13lg https://dev.to/temur_khasanov_935b6ed893/how-to-estimate-battery-runtime-from-wh-dod-efficiency-and-load-13lg <p>Battery runtime estimates are usually simple in structure but easy to overstate. A useful first-pass formula is:<br> </p> <div class="highlight js-code-highlight"> <pre class="highlight plaintext"><code>usable Wh = nominal Wh x depth of discharge x system efficiency runtime hours = usable Wh / load W </code></pre> </div> <p>Example:<br> </p> <div class="highlight js-code-highlight"> <pre class="highlight plaintext"><code>nominal battery capacity = 1200 Wh depth of discharge = 80% system efficiency = 90% load = 100 W usable Wh = 1200 x 0.8 x 0.9 = 864 Wh runtime = 864 / 100 = 8.64 hours </code></pre> </div> <p>That is a planning estimate, not a guarantee. Real runtime can be lower because of battery age, temperature, voltage sag, BMS cutoff, inverter idle draw, surge loads, wiring losses, and load variation.</p> <p>For AC loads through an inverter, the inverter's efficiency and idle consumption matter. A small always-on inverter load can materially reduce runtime, especially with low-power devices.</p> <p>I made a free calculator that applies this same logic and shows the assumptions:</p> <p><a href="https://speccalchub.com/en/calculators/battery-runtime" rel="noopener noreferrer">https://speccalchub.com/en/calculators/battery-runtime</a></p> <p>Disclosure: I'm the creator of this free tool.</p> energy tutorial beginners