Battery Backup Calculator
Calculate how long a battery or UPS can power your devices based on battery capacity, voltage, and the total load connected.
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Result
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Formula
How it works: Converts battery capacity (Ah × V) to watt-hours, applies efficiency loss, then divides by the connected load to find runtime.
Worked Example
Frequently Asked Questions
Why include inverter efficiency?
Inverters lose 10-20% of energy as heat during DC to AC conversion. An 85% efficiency is a common real-world value.
What is Ah?
Ampere-hours (Ah) measures battery capacity. A 150Ah battery can theoretically deliver 15 amps for 10 hours or 1 amp for 150 hours.
Should I fully discharge my battery?
No. Deep discharging damages lead-acid batteries. Only use 50-60% of rated capacity for longevity. Lithium batteries can safely use 80-90%.
Can I embed this Battery Backup Calculator on my website?
Yes. Click the "Embed" button at the top of this page to customize the size, colors, and theme, then copy the iframe code. Paste it into any HTML page, WordPress site, or CMS. It is completely free, requires no signup, and works on all devices. You can also visit our embed guide at calculory.com/services/embed-calculators for more details.
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I can help you understand the battery backup calculator formula, interpret your results, and answer follow-up questions.
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